RU2612918C1 - Device for determining positions of defects on aspherical surface of optical part (versions) - Google Patents

Abstract

FIELD: test and measurement equipment.

SUBSTANCE: invention relates to test and measurement equipment and is aimed at increasing the accuracy of determining positions of defects on aspherical surfaces of both the second and a higher order during their formation. Device comprises a monochromatic light source, an afocal system, a beam splitter to form the reference and the object branches and a receiving part. In the object branch there are the first focusing lens with a diaphragm in its back focal plane, a synthesized holographic optical element consisting of an axial synthetic hologram-compensator and two coaxial with it adjustment holograms, in the reference branch there is a flat reference mirror fixed perpendicularly to the beams propagating from the beam splitter, in the receiving part there are in series: a rotary flat mirror, the second focusing lens, a photodetector and an information display unit. Herewith in one version the device additionally contains one mark with two crossing each other strokes installed between the beam splitter and the first focusing lens and aligned with an intermediate image of the aspherical surface of the optical part, in another version the device contains two marks, each with two crossing each other strokes, one of which is located between the afocal system and the beam splitter and aligned with the intermediate image of the aspherical surface, and the second mark is located in the receiving part between the flat rotary mirror and the second focusing lens and is aligned with the intermediate image of the aspherical surface of the optical part.

EFFECT: technical result is the increase of accuracy of determining positions of defects on an aspherical surface of an optical part.

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Description

The present invention relates to instrumentation and can be used in optical production to control the aspherical surfaces of optical parts during their shaping.

A device for determining the positions of defects on aspherical surfaces of the second order of optical parts [Puryaev D.T. Control methods for optical aspherical surfaces. M., "Engineering", 1976, S. 83-87]. The device contains a radiation source and a condenser, a diaphragm, a collimator lens forming a parallel beam of light rays, a beam splitter designed to separate a parallel beam of light rays into two branches — the reference and the object, installed in the object branch along the transmitted beam splitter — installed in series with the light beams. a focusing lens and an autocollimation mirror, installed in the reference branch perpendicular to a parallel beam of light rays reflected from the beam splitter a flat mirror reflecting a parallel beam of light rays incident on it to a beam splitter passing a part of this light beam into a receiving part containing a telescopic magnifier

In the control process, an optical part with an aspherical surface is installed in the object branch of the device so that the geometric focus F _{1 of the} controlled aspherical surface coincides with the focus F 'of the focusing lens. As a result, a beam of light rays illuminating an aspherical surface after reflections in series from an aspherical surface, an autocollimation mirror, an aspherical surface, and a beam splitter will come from the object branch to the receiving part. The interference pattern formed in the receiving part as a result of the interference of light waves corresponding to beams of light rays coming from the object and support branches is observed visually and photographed using a telescopic magnifier. Through the interference fringes of this pattern, the positions of the defects on a controlled aspherical surface are visualized. An approximate formula is used to determine the y coordinate of these defects

where y is the ordinate of the aspherical surface in the Cartesian coordinate system, the center of which is aligned with the vertex of the aspherical surface,

OF ₁ - parameter of the geometric focus of the controlled aspherical surface of the second order,

- фокусное расстояние фокусирующего объектива в объектной ветви,

- the focal length of the focusing lens in the object branch,

h is the height at which the beam propagating from the beam splitter enters the focusing lens. Since the equation of the initial aspherical surface and the focal length of the focusing lens are known, using this formula it becomes possible to determine the y coordinate from the measured value of h, which is determined by the interference pattern as half the distance between symmetrical points with distortions of the interference band or as the radius of the interference ring.

The disadvantage of this device is that it allows you to control aspherical surfaces only of the second order. This is due to the fact that the device’s principle of operation is based on the use of the properties of anaberration points of second-order aspherical surfaces and the use of an autocollimation mirror in this case, either spherical (when controlling hyperbolic, elliptic and parabolic surfaces), or flat (when controlling parabolic surfaces).

The disadvantage of this device is also that the determination of the y coordinate of defects on the surface under control according to the above formula is only suitable for zonal (axisymmetric) errors, and for local (non-axisymmetric) defects, the y coordinates cannot be determined, since the height h in this case it is impossible to measure from the interference pattern. In addition, this device has low accuracy due to the use of approximate formula (1) to find the coordinate y of the aspherical surface.

The closest in technical essence to the proposed group of inventions is a device for determining the positions of defects on the aspherical surfaces of optical parts [Larionov NP, Lukin AV, Nyushkin AA Control of small-sized aspherical optics using synthesized holograms // Optical Journal, 2011, v. 78, No. 4, P. 61-64]. This device contains a monochromatic light source (laser) and an afocal system sequentially installed along the light rays, a beam splitter for forming the reference and object branches and a receiving part, installed in the object branch along the light rays propagating from the beam splitter, the first focusing lens for forming a converging homocentric a beam of light rays with a luminous dot in its back focus, a synthesized hologram optical element consisting of three axial coaxial between synthesized holograms, one of which is a compensating hologram, and the other two holograms are quotation marks, a flat reference mirror installed in the supporting branch perpendicular to the light rays propagating from the beam splitter, installed in the receiving part along the light rays propagating from the beam splitter, focusing lens, photodetector and information display unit.

In this device, defects on the controlled aspherical surface of the optical part are determined by analyzing the interference pattern recorded by the photodetector and displayed on the screen of the information display unit.

The disadvantage of this device is the low accuracy of determining the positions of defects on the aspherical surface of the optical part, due to the fact that the device does not have a mechanism for accurately determining the position of defects.

The task to which the proposed technical solution is directed is to increase the accuracy of determining the positions of defects on aspherical surfaces of both second and higher orders.

The solution of this problem is achieved by the fact that in the proposed device for determining the positions of defects on the aspherical surface of an optical part containing a monochromatic light source and an afocal system sequentially installed along the light rays, a beam splitter for forming the support and object branches and the receiving part, installed in the object branch by the first light focusing lens to form a converging homocentric beam of light propagating from the beam splitter of rays with a luminous point in its back focus, a synthesized hologram optical element consisting of three axial coaxial synthesized holograms, one of which is a compensating hologram, and the other two holograms are quotation marks, a flat reference mirror mounted in the reference branch perpendicular to light rays propagating from the beam splitter installed in the receiving part along the light rays propagating from the beam splitter, the second focusing lens, photodetector the triad and the information display unit, the device additionally contains a mark with two intersecting strokes located between the beam splitter and the first focusing lens and combined with an intermediate image of the aspherical surface of the optical part, the mark being fixed in a node equipped with an angular rotation mechanism for angular orientation of the mark and three linear carriages for the possibility of shifting marks in three mutually perpendicular directions, one of which is perpendicular to the flatness of the location of its strokes, for which each linear carriage is equipped with a drive connected to the drive control unit, in order to be able to measure the displacement of the brand, each linear carriage is equipped with a linear displacement sensor connected to the input of the digital display unit, in the receiving part along the light rays after the beam splitter a flat rotary mirror is installed, a diaphragm is installed in the rear focal plane of the first focusing lens;

as well as the fact that both strokes of the mark intersect each other at an angle of 90 degrees and each of them is oriented parallel to one of the two directions of the stamp’s displacement, parallel to the plane of arrangement of two strokes intersecting each other.

The solution of this problem is achieved by the fact that in the proposed device for determining the positions of defects on the aspherical surface of an optical part containing a monochromatic light source and an afocal system sequentially installed along the light rays, a beam splitter for forming the support and object branches and the receiving part, installed in the object branch by the first light focusing lens to form a converging homocentric beam of light propagating from the beam splitter of rays with a luminous point in its back focus, a synthesized hologram optical element consisting of three axial coaxial synthesized holograms, one of which is a compensating hologram, and the other two holograms are quotation marks, a flat reference mirror mounted in the reference branch perpendicular to light rays propagating from the beam splitter installed in the receiving part along the light rays propagating from the beam splitter, the second focusing lens, photodetector the triad and the information display unit, the device further comprises a first mark with two intersecting strokes located between the afocal system and the beam splitter and combined with the first intermediate image of the aspherical surface of the optical part, while the first mark is fixed in the first node equipped with an angular rotation mechanism for angular orientation of the first mark and three linear carriages to enable the first mark to be displaced in three mutually perpendicular directions, one of which it is perpendicular to the plane of its strokes, for which each linear carriage is equipped with a drive connected to the first drive control unit, to enable measurement of the displacement of the first mark, each linear carriage is equipped with a linear displacement sensor connected to the input of the first digital display unit, in the reception parts along the light rays after the beam splitter installed a flat rotary mirror, introduced a second mark with two intersecting strokes, which together it with a second intermediate image of the aspherical surface of the optical part and is fixed in the second node equipped with an angular rotation mechanism for angular orientation of the second mark and three linear carriages to enable the second mark to be displaced in three mutually perpendicular directions, one of which is perpendicular to the plane of its strokes, why each linear carriage is equipped with a drive connected to the second drive control unit, to enable measurement of the value, see scheniya second linear mark, each carriage is provided with a linear displacement sensor connected to the second input digital display unit, in the back focal plane of the first aperture of the focusing lens is set;

as well as the fact that both strokes of each mark intersect each other at an angle of 90 degrees and each of them is oriented parallel to one of the two directions of displacement of the corresponding mark parallel to the plane of arrangement of two strokes intersecting each other.

In FIG. 1 shows a schematic optical diagram of the proposed device for determining the positions of defects on the aspherical surface of an optical part using one brand M located in the object branch between the beam splitter and the first focusing lens.

In FIG. 2 shows a schematic optical diagram of the proposed device for determining the positions of defects on the aspherical surface of an optical part using two grades M1 and M2, one of which (M1) is located between the afocal system and the beam splitter, and the second (M2) is in the receiving part between the flat rotary mirror and a second focusing lens.

In FIG. 3 and FIG. Figure 4 shows the interferograms obtained by monitoring a specific aspherical surface of the optical part proposed by the device (Fig. 2) using the M1 brand located between the afocal system and the beam splitter, and the M2 brand located in the receiving part between the flat rotary mirror and the second focusing lens.

для формирования в заднем фокусе светящейся точки A, диафрагма 11, расположенная в задней фокальной плоскости первого фокусирующего объектива 10, синтезированный голограммный оптический элемент 12, расположенный на расстоянии s от светящейся точки A до точки O₁ на передней поверхности его подложки и состоящий из трех осевых соосных между собой синтезированных голограмм: голограммы-компенсатора 13, формирующей в проходящем свете осесимметричный пучок световых лучей, ось которого задает оптическую ось в объектной ветви, юстировочной голограммы 14, формирующей в отраженном свете автоколлимационное изображение A'₁₄ светящейся точки A, и юстировочной голограммы 15, формирующей в проходящем свете светящуюся точку-репер A_реп, расположенную на расстоянии d₂ от точки О₂ на задней поверхности подложки синтезированного голограммного оптического элемента 12 и совпадающую с вершиной О₃ асферической поверхности 16. Толщина подложки синтезированного голограммного оптического элемента 12 равна d₁. Марка М ориентирована таким образом, чтобы плоскость расположения ее двух пересекающихся между собой штрихов была совмещена с плоскостью промежуточного изображения ППИ асферической поверхности 16 оптической детали 17, расположенной между светоделителем 3 и первым фокусирующим объективом 10. В приемной части по ходу световых лучей, распространяющихся от светоделителя 3, установлены плоское поворотное зеркало 18, второй фокусирующий объектив 19, фотоприемное устройство (например, цифровая видеокамера) 20 с плоскостью регистрации 21 его светочувствительных элементов и блок отображения информации (например, монитор) 22. Устройство также содержит приводы 23, 24 и 25, соединенные с линейными каретками 7, 8 и 9 соответственно и подключенные к блоку управления приводами 26 для придания смещений марке М в трех взаимно перпендикулярных направлениях, датчики линейных перемещений 27, 28 и 29, которыми снабжены линейные каретки 7, 8 и 9, соответственно подключенные к входу блока цифровой индикации 30 величин смещений марки М в трех взаимно перпендикулярных направлениях.The proposed device (in Fig. 1) for determining the positions of defects on the aspherical surface of the optical part contains a monochromatic (laser) light source 1, sequentially installed along the path of the light rays afocal system 2, a beam splitter 3, dividing the incident beam of light rays into two beams, one of which (reflected from the beam splitter 3) enters the reference branch, and the other (the last beam splitter 3) enters the object branch of the device. In the reference branch, perpendicular to the light rays propagating from the beam splitter 3, a flat reference mirror 4 is installed. In the object branch, a node 5 is sequentially mounted along the light rays with the M mark attached to it, while the node 5 is equipped with an angular rotation mechanism 6 and linear carriages 7 8 and 9 for the angular orientation of the M mark and its displacement by linear carriages in three mutually perpendicular directions, the first focusing lens 10 with a rear focal length

to form a luminous point A in the back focus, an aperture 11 located in the rear focal plane of the first focusing lens 10, a synthesized hologram optical element 12 located at a distance s from the luminous point A to the point O ₁ on the front surface of its substrate and consisting of three axial synthesized holograms coaxial with each other: a hologram-compensator 13, forming in transmitted light an axisymmetric beam of light rays, the axis of which defines the optical axis in the object branch, an adjustment hologram we 14 forming reflected light autocollimating image A _'14 the luminous point A, and the adjustment of the hologram 15, forming in transmitted light bright spot-frame A _rap, disposed at a distance d ₂ from the point O ₂ to the rear surface of substrate synthesized hologram optical element 12 and coinciding with the vertex O _{3 of the} aspherical surface 16. The thickness of the substrate of the synthesized hologram optical element 12 is equal to d ₁ . Mark M is oriented in such a way that the plane of the location of its two intersecting strokes is aligned with the plane of the intermediate image of the PPI of the aspherical surface 16 of the optical part 17 located between the beam splitter 3 and the first focusing lens 10. In the receiving part along the light rays propagating from the beam splitter 3, a flat rotary mirror 18, a second focusing lens 19, a photodetector (for example, a digital video camera) 20 with a registration plane 21 of its light are installed elements and an information display unit (for example, a monitor) 22. The device also includes actuators 23, 24 and 25 connected to linear carriages 7, 8 and 9, respectively, and connected to the drive control unit 26 to bias the M mark in three mutually perpendicular directions , linear displacement sensors 27, 28 and 29, which are equipped with linear carriages 7, 8 and 9, respectively connected to the input of the digital display unit of 30 magnitudes of the M displacements in three mutually perpendicular directions.

для формирования в заднем фокусе светящейся точки A, диафрагма 11, расположенная в задней фокальной плоскости первого фокусирующего объектива 10, синтезированный голограммный оптический элемент 12, расположенный на расстоянии s от светящейся точки A до точки O₁ на передней поверхности его подложки и состоящий из трех осевых соосных между собой синтезированных голограмм: голограммы-компенсатора 13, формирующей в проходящем свете осесимметричный пучок световых лучей, ось которого задает оптическую ось в объектной ветви, юстировочной голограммы 14, формирующей в отраженном свете автоколлимационное изображение A'₁₄ светящейся точки A, и юстировочной голограммы 15, формирующей в проходящем свете светящуюся точку-репер А_реп, расположенную на расстоянии d₂ от точки О₂ на задней поверхности подложки синтезированного программного оптического элемента 12 и совпадающую с вершиной О₃ асферической поверхности 16. Толщина подложки синтезированного голограммного оптического элемента 12 равна d₁. В приемной части по ходу световых лучей, распространяющихся от светоделителя 3, установлены плоское поворотное зеркало 18, вторая марка М2, второй фокусирующий объектив 19, фотоприемное устройство (например, цифровая видеокамера) 20 с плоскостью регистрации 21 его светочувствительных элементов и блок отображения информации (например, монитор) 22. Плоскость расположения штрихов первой марки M1 совмещена с плоскостью первого промежуточного изображения ППИ1, расположенного между афокальной системой 2 и светоделителем 3. Линейные каретки 7, 8 и 9 первого узла 5 для крепления первой марки M1 снабжены приводами 23, 24 и 25 соответственно, которые подключены к первому блоку управления приводами 26 для придания смещений первой марке M1 в трех взаимно перпендикулярных направлениях. Для измерения величин смещений первой марке M1 служат датчики линейных перемещений 27, 28 и 29, которыми снабжены линейные каретки 7, 8 и 9 соответственно и которые подключены к входу первого блока цифровой индикации 30 величин смещений первой марки M1 в трех взаимно перпендикулярных направлениях. Вторая марка М2 введена в приемную часть после плоского поворотного зеркала 18. При этом она закреплена во втором узле 33, снабженном механизмом угловых поворотов 34 для угловой ориентации второй марки М2 и линейными каретками 35, 36 и 37 для смещения ее в трех взаимно перпендикулярных направлениях. Плоскость расположения штрихов второй марки М2 совмещена с плоскостью второго промежуточного изображения ППИ2, расположенного между плоским поворотным зеркалом 18 и вторым фокусирующим объективом 19. Линейные каретки 35, 36 и 37 второго узла 33 крепления второй марки М2 снабжены приводами 38, 39 и 40 соответственно, которые подключены к второму блоку управления приводами 41 для придания смещений второй марке М2 в трех взаимно перпендикулярных направлениях. Для измерения величин смещений второй марки М2 служат датчики линейных перемещений 42, 43 и 44, которыми снабжены линейные каретки 35, 36 и 37 соответственно и которые подключены к входу второго блока цифровой индикации 45 величин смещений второй марки М2 в трех взаимно перпендикулярных направлениях.The proposed device (in Fig. 2) for determining the positions of defects on the aspherical surface of the optical part contains a monochromatic (laser) light source 1, an afocal system 2, a first brand M1, a beam splitter 3 separating the incident light beam incident on it, sequentially installed along the light rays into two beams, one of which (reflected from the beam splitter 3) enters the reference branch, and the other (past beam splitter 3) - into the object branch of the device. In the reference branch, perpendicular to the light rays propagating from the beam splitter 3, a flat reference mirror 4 is installed. The first mark M1 is fixed in the first node 5, equipped with an angular rotation mechanism 6 for the angular orientation of the first mark M1 and linear carriages 7, 8 and 9 to shift it in three mutually perpendicular directions. In the object branch along the light rays passing the beam splitter 3, the first focusing lens 10 with a rear focal length is sequentially mounted

to form a luminous point A in the back focus, an aperture 11 located in the rear focal plane of the first focusing lens 10, a synthesized hologram optical element 12 located at a distance s from the luminous point A to the point O ₁ on the front surface of its substrate and consisting of three axial synthesized holograms coaxial with each other: a hologram-compensator 13, forming in transmitted light an axisymmetric beam of light rays, the axis of which defines the optical axis in the object branch, an adjustment hologram we 14 forming reflected light autocollimating image A _'14 the luminous point A, and the adjustment of the hologram 15, forming in transmitted light bright spot-frame A _rap, disposed at a distance d ₂ from the point O ₂ to the rear surface of substrate synthesized by the software of the optical element 12 and coinciding with the vertex O _{3 of the} aspherical surface 16. The thickness of the substrate of the synthesized hologram optical element 12 is equal to d ₁ . In the receiving part along the light rays propagating from the beam splitter 3, a flat rotary mirror 18, a second brand M2, a second focusing lens 19, a photodetector (for example, a digital video camera) 20 with a registration plane 21 of its photosensitive elements and an information display unit (for example , monitor) 22. The plane of the strokes of the first mark M1 is aligned with the plane of the first intermediate image PPI1, located between the afocal system 2 and the beam splitter 3. Linear carriages 7, 8 and 9 per th unit 5 for fixing the first mark M1 provided with actuators 23, 24 and 25 respectively, which are connected to first drive control unit 26 to make the displacement of the first mark M1 in three mutually perpendicular directions. To measure the displacement values of the first mark M1, linear displacement sensors 27, 28 and 29 are used, which are equipped with linear carriages 7, 8 and 9, respectively, and which are connected to the input of the first digital display unit 30 of the displacement values of the first mark M1 in three mutually perpendicular directions. The second mark M2 is introduced into the receiving part after the flat rotary mirror 18. At the same time, it is fixed in the second node 33, equipped with an angular rotation mechanism 34 for the angular orientation of the second mark M2 and linear carriages 35, 36 and 37 for its displacement in three mutually perpendicular directions. The plane of the strokes of the second brand M2 is aligned with the plane of the second intermediate image PPI2 located between the flat rotary mirror 18 and the second focusing lens 19. The linear carriages 35, 36 and 37 of the second attachment unit 33 of the second brand M2 are equipped with drives 38, 39 and 40, respectively, which connected to the second drive control unit 41 to bias the second brand M2 in three mutually perpendicular directions. Linear displacement sensors 42, 43 and 44, which are equipped with linear carriages 35, 36 and 37, respectively, and which are connected to the input of the second digital display unit 45 of the displacement values of the second mark M2, are used to measure the displacements of the second grade M2 in three mutually perpendicular directions.

The proposed device (in Fig. 1) for determining the positions of defects on the aspherical surface of the optical part operates as follows. The beam of light rays from a monochromatic (laser) light source 1 enters the afocal system 2 and is converted by it into an expanded parallel beam of light rays, which enters the beam splitter 3, where it partially passes and is partially reflected by it. The reflected part of the beam of light rays enters the reference branch of the device, falls on a flat reference mirror 4, oriented perpendicular to the light rays of this beam, is reflected from it and partially reflects from the beam splitter 3 in the autocollimation process and partially passes through it. The reflected part of the reference beam of light rays passes in the opposite direction to the afocal system 2 and falls into the opening of the output window of the light source 1, and the transmitted beam splitter 3 part of the reference beam enters the receiving part, is reflected from the planar rotary mirror 18 and enters the second focusing lens 19, which focuses on point A _o , which serves as a reference point in the device. Then this part of the reference beam of light rays passes through the lens of the photodetector device (for example, a digital video camera) 20 and falls on the registration plane 21 of the photosensitive elements of the photodetector device 20.

The object beam of the device receives the transmitted beam splitter 3 of the parallel beam of light rays emerging from the afocal system 2, which passes mark M in this branch, the first focusing lens 10, transforming it into a converging homocentric beam of light rays centered in the form of a luminous point A in the back focus of the lens 10, passes through the diaphragm 11 located in the rear focal plane of the lens 10, and falls on the synthesized hologram optical element 12 in the form of a diverging homocentric beam of light illuminating the hologram-compensator 13 and quotation holograms 14 and 15. The hologram-compensator 13 during the diffraction of light by it in transmitted light forms an axisymmetric beam of light rays, each beam of which falls on the aspherical surface 16 of the optical part 17 according to a certain normal this surface and is reflected from it in the opposite direction. In this case, the reflective aspherical surface 16 of the optical part 17 acts as an object. Reflected from surface 16 of the aspherical optical component 17 in the light beam during autocollimation propagates to the hologram-compensator 13, and as a result of diffraction on it focuses to a point A _'16 which is autocollimation image luminous point A. Then, the light beam passes countercurrently the direction of the diaphragm 11 and the first focusing lens 10, which converts it into a parallel beam of light rays. During this parallel beam of light rays through the synthesized hologram-compensator 13 and the first focusing lens 10, an image of the aspherical surface 16 of the optical part 17 is formed, which is intermediate and reverse. It is located in the plane of the intermediate image PPI. In this regard, the point O ' ₃ lying in the center of the intermediate image of the aspherical surface 16, and hence on the optical axis, is optically conjugated with the vertex O _{3 of the} aspherical surface 16 of the optical part 17 and is its image. Similarly, the point G lying in the plane of the intermediate image of the PPI is the image of the point E located near the boundary of the aspherical surface 16 of the optical part 17.

The plane of arrangement of strokes of mark M is aligned with the plane of the intermediate image of the PPI. It is obvious that in this case, in the plane of the intermediate image of the PPI in the reverse ray path from the aspherical surface 16 of the optical part 17, an image of the brand M will also be formed. Next, a parallel beam of light rays after passing through mark M falls on a beam splitter 3 and is divided into two beams, one of which, having passed a beam splitter 3, propagates to the afocal system 2, and the other, reflected from a beam splitter 3, enters iemnuyu portion where reflected from a plane deflecting mirror 18, passes a second focusing lens 19, which it is focused to a point A '' _16, passes the lens photoreception device (e.g., digital cameras) 20 and falls at the front plane 21 of photosensitive elements photodetector 20. By means of a beam splitter 3, a flat rotary mirror 18, a second focusing lens 19, and a lens of a photodetector (for example, a digital video camera) 20, the one formed in PPI oskosti intermediate image intermediate image surface 16 of the aspherical optical member 17. As a result, in the recording plane 21 is formed resulting image aspherical surface 16 of the optical member 17, which is straight. An image of M-strokes is also projected onto the same registration plane 21. As a result of combining light beams coming from the reference and object branches in the receiving part and resulting in the interference of the corresponding light waves, an interference pattern is formed for the controlled aspherical surface 16 optical part 17, which is also displayed in the registration plane 21. The final image of the aspherical surface 16 of the optical part 17, together with the image of this interference pattern They, as well as M marks, are transmitted by a photodetector (for example, a digital video camera) 20 to the screen of the information display unit (for example, a monitor) 22, where 31 is the final image of the aspherical surface 16 of the optical part 17, with its corresponding interference pattern, and the IS _m strokes mark image M. The screen display unit (e.g., monitor) 22 shown point O '' _3, located in the center of the image 31, the aspheric surface 16 of the optical member 17 and the interference pattern for this aspherical surface ty. In this regard, it corresponds to the point O ' ₃ in the plane of the intermediate image of the PPI and point O ₃ - the top of the aspherical surface 16 of the optical part 17. In order to conveniently and clearly identify defects and determine their location on the controlled aspherical surface 16 of the optical part 17, it is necessary that on the screen of the information display unit (for example, a monitor) 22 a direct image of the aspherical surface 16 of the optical part 17 is formed. For this, the body of the photodetector (for example, digital video camera) 20 rotate 180 ° around its optical axis relative to the initial working position of the photodetector (for example, a digital video camera) 20.

Defects on the controlled aspherical surface 16 of the optical part 17 are determined by visual analysis of the interference pattern present on the final image 31 of this aspherical surface 16 on the screen of the information display unit (for example, a monitor) 22. Defects and their positions on the controlled aspherical surface 16 are visualized by curvature of the stripes in this interference picture. According to the degree of distortion of interference fringes, characteristic points are selected on the controlled aspherical surface 16, to which the greatest defects correspond and which must be eliminated first of all. Then determine the position of these characteristic points with defects on the controlled aspherical surface 16 relative to its top.

The aspherical surface 16 is defined by an equation in the rectangular coordinate system oxyz, the center of which is aligned with the vertex O _{3 of the} aspherical surface 16, and the axis oz coincides with its axis of symmetry. In the circuit of FIG. 1, the axes oy and oz lie in the plane of the figure; in this case, the oy axis is directed upward, and the oz axis is directed from left to right. The x axis lies in a plane perpendicular to the plane of the figure. In this regard, the axes ox and oy lie in two mutually perpendicular meridional planes. Let the axes ox, oy, and oz form a right-handed system of rectangular coordinates. Then the axis oX, being perpendicular to the plane of the figure, will be directed away from the observer. Based on these data, the node 5 with the mark M is installed in such a way that, by means of the linear carriage 7, the mark M moves parallel to the axis oz, by means of the linear carriage 8 parallel to the axis oh, and by linear carriage 9 parallel to the axis oy.

The synthesized hologram optical element 12 can be performed on a plane-parallel, plane-concave or plane-convex substrate with a given thickness d ₁ and refractive index n (λ) of the substrate material, where λ is the wavelength of the monochromatic light source. The calculation of the structure parameters of the synthesized holograms, segments of the optical control scheme of the aspherical surface of the second and higher orders, the methods and means for displaying the structure of the synthesized holograms on the substrate, as well as the methods of adjusting the control schemes of the aspherical surfaces are considered in the dissertation for the degree of candidate of technical sciences N. Larionova. P. (see Larionov N.P. Methods and means of controlling the shape of aspherical surfaces of large and fast optical elements based on the use of axial synthesized holograms. Kazan, 2002, pp. 40-47, 136-142), as well as in the materials for the invention (see Larionov NP, Lukin AV, Mustafin KS, Rafikov RA A way to configure a device for monitoring optical surfaces. - RF Patent No. 729437, Bull. Inventor, 1980, No. 5).

Grade M contains two thin strokes intersecting each other at an angle of 90 °, applied, for example, on one of the surfaces of a thin glass plate transparent to the radiation of light source 1. The thickness of the strokes of grade M can be, for example, 0.015 mm. It is fixed in node 5 so that the plane of its strokes is oriented perpendicular to the direction of displacement of the M mark, carried out by means of the linear carriage 7 under the influence of the drive 23 and the drive control unit 26. In two other mutually perpendicular directions, the M mark is shifted by linear carriages 8 and 9 under the influence of the drives 24 and 25, respectively, and the drive control unit 26. In this case, the mark M is fixed in the node 5 so that one of its strokes is oriented parallel to the offset of the M mark carried out by the linear carriage 8, and the other stroke is parallel to the direction of the M mark offset by the linear carriage 9. The values of the M mark displacements are measured by linear displacement sensors 27, 28 and 29, mounted on the linear carriages 7, 8 and 9, respectively, and connected to the digital display unit 30.

When controlling the aspherical surface 16 of the optical part 17, it is necessary to conduct quotation operations, the most important of which are discussed below.

First, a flat reference mirror 4 is oriented in the reference branch perpendicularly to a parallel beam of rays incident on it, propagating from the beam splitter 3. For this, the reference beam of rays reflected from it is directed to the beam splitter 3 by angular tilts of the mirror 4, and then the part of the reference beam reflected from the beam splitter 3 is directed into the afocal system 2 and then into the exit window of the laser 1. The transmitted beam splitter 3 part of the reference beam enters the receiving part of the device, where after reflection from a flat rotary mirror 18 post falls into the second focusing 19 and focuses them at the point A _about , which serves as a reference point in the device. Then this part of the reference beam of rays passes through the lens of the photodetector device (for example, a digital video camera) 20 and falls on the registration plane 21 of the photosensitive elements of the photodetector device (for example, a digital video camera) 20.

Then, the synthesized hologram optical element 12 is adjusted. For this, first, it is shifted perpendicular to the optical axis of the first focusing lens 10 and it is ensured that its aperture is illuminated by the diverging homocentric beam of light rays incident on it emanating from the luminous point A. After this, the displaced synthesized hologram optical element 12 along the optical axis of the lens 10 and angular rotations it is obtained by means of an alignment hologram 14 auto-collimation image CONTROL A _'14 the luminous point A, which is formed as a result of diffraction in the opposite direction of rays incident on the hologram 14. The process of forming images autocollimation A' ₁₄ is controlled visually by watching this image preliminarily on the diaphragm 11 in the vicinity of its opening and thus achieving its minimum size by longitudinal displacement of the synthesized hologram optical element 12. After that, the beam of light rays diffracted on the adjustment hologram 14 by means of angular rotations of the synthesizer The mounted hologram optical element 12 is directed into the opening of the diaphragm 11, which passes in the opposite direction to the first focusing lens 10, converting it into a parallel beam of rays, then is reflected from the beam splitter 3 and enters the receiving part, where it is reflected from a flat rotary mirror 18, the second focusing the lens 19, focusing it to the point A ″ ₁₄ , passes the lens of the photodetector (for example, a digital video camera) 20 and falls on the registration plane 21 of the photodetector 20. As a result, Further, the beams of light rays that arrived at the receiving part from the reference and object branches, in the registration plane 21 there will be an interference pattern, which will be displayed on the screen of the information display unit (for example, a monitor) 22 in the form of pieces of interference fringes located in the ring picture 32. These the segments must be rectilinear and lie on a system of virtual straight lines with a constant step. If this is not done, then it is necessary to obtain the aforementioned location of the segments of interference fringes in the annular pattern 32 by the longitudinal displacements of the synthesized hologram optical element 12. Then, by angular inclination of the synthesized hologram optical element 12, it is necessary to tune to an infinitely wide band or to a minimum number of interference fringes and control state in the ring pattern 32 in the process of operation of the device. This state corresponds to the fact that the adjustment hologram 14 indeed forms an autocollimation image A ′ _{14 of the} luminous point A, which means that the compensator hologram 13 and the synthesized hologram optical element 12 are installed at a given distance s from the luminous point A. For this state, point A '' ₁₄ is focused in the focal plane of the second focusing lens 19 and is practically aligned with the reference point A _about .

Then, the optical part 17 is aligned with the controlled aspherical surface 16. The alignment of the symmetry axis of the aspherical surface 16 with the symmetry axis of the hologram-compensator 13 (optical axis) can be controlled by the type of interference fringes in picture 31 on the screen of the information display unit (for example, a monitor) 22, the left and right parts of which should be close to each other in the form of interference fringes. However, this method can only be used if large non-axisymmetric defects are absent on the controlled aspherical surface 16. More reliable is the method based on the visual observation of the image of point A '' ₁₆ , which is projected together with the image of the reference point A _о onto the registration plane 21 through the lens of a photodetector device (for example, a digital video camera) and observed on the screen of the information display unit (for example, monitor) 22. By means of lateral displacements and angular rotations of the part 17, the image of point A '' ₁₆ as close as possible to the axisymmetry is achieved and it is combined with the image of the reference point A _about , observing them on the screen not the information display unit (for example, a monitor) 22. The location of the vertex O _{3 of the} aspherical surface 16 relative to the point O ₂ is controlled by the shape of the A '' _rep point in the focal plane of the second focusing lens 19, the image of which is also displayed on the screen of the information display unit (for example , monitor) 22. Point A '' _{rep is} formed by a beam of light rays formed by the alignment hologram 15 in transmitted light when it is illuminated from the luminous point A. This beam of light rays focuses to point A _rep . It falls on the aspherical surface 16, is reflected from it, passes in the reverse direction of the quotation hologram 15, focusing on the point A ' _rep as a result of diffraction on this hologram, then the first focusing lens 10 passes and after reflection from the beam splitter 3 and a flat rotary mirror 18 focuses second focusing lens 19 to point A '' _rep . By longitudinally displacing the part 17, a minimum image of the _rep point A ’on the screen of the information display unit (for example, a monitor) 22 is obtained, which corresponds to the fact that the _rep point A will be located on the aspherical surface 16 and coincide with its vertex — point O ₃ , which will be at a distance d ₂ from the point O ₂ on the back surface of the substrate of the synthesized hologram optical element 12. After conducting the considered quotation operations of the part 17 by focusing the lens of the photodetector (for example, digital video cameras) 20 more carefully project the image of the aspherical surface 16 of the optical part 17 onto the registration plane 21, which is visually controlled by the sharpness of the image on the screen of the information display unit (for example, a monitor) 22 of a small mark temporarily applied to the aspherical surface 16, or a small fragment tissue paper, also glued temporarily to the aspherical surface 16. Then, the applied mark or piece of tissue paper is removed.

Next, the M mark is adjusted. First, it is oriented by the mechanism of angular rotations 6 of the assembly 5 so that the plane of its strokes is perpendicular to the parallel beam of light rays emerging from the afocal system 2 and passing through the beam splitter 3. The control of such an installation of mark M is carried out using an additional auxiliary a flat mirror, which is leaned against the frame of the brand M with a reflective coating on the side facing the first focusing lens 10. By means of the mechanism of angular rotations 6, they are directed from The parallel beam of light rays reflected from an additional auxiliary plane mirror into the afocal system 2, and then the narrow beam of rays emerging from it, into the exit window of the laser 1. Then, the plane of location of the M-brand strokes is combined with the plane of the intermediate PPI image. For this, a longitudinal displacement of the M mark is carried out along the parallel beam of light rays incident on it by means of a linear carriage 7 driven by the drive 23 and the drive control unit 26. The moment of alignment of the plane of location of the strokes of the M brand with the PPI plane is monitored by the appearance of a sharp image of IS strokes _m mark M on the screen of the information display unit (for example, a monitor) 22.

After carrying out the adjustment operations described above, interference fringes are obtained on the screen of the information display unit (for example, a monitor) 22 by turning the part 17 around, for example, the axis oX and proceed to analyze the interference pattern 31 in order to detect defects on the controlled aspherical surface 16 of the optical part 17 and the selection of the most characteristic ones, which correspond to the largest defects and which must be eliminated in the first place. Then determine the position of these characteristic points with defects on the controlled aspherical surface 16 relative to its top. For this, the intersection point of two strokes of mark M is first drawn onto the optical axis and thereby combine it with the point at which point O ' ₃ should be located, which is optically conjugated with the vertex O _{3 of the} aspherical surface 16. This alignment is carried out by moving mark M in the plane of the intermediate images of PPI in two mutually perpendicular directions using linear carriages 8 and 9 under the influence of drives 24 and 25 and the control unit of the drives 26. Control output on the optical axis of the point of intersection of two strokes of brand M travel, observing, for example, a magnifying glass by the aspherical surface 16, the point of intersection of their overlapping shadows with light-point datum A _rap, situated on the optical axis. (To carry out this operation, part 17 is temporarily removed from the control circuit, and then returned). The readings for linear displacement sensors 28 and 29 on the digital display unit 30, obtained during this operation, serve as a reference when measuring the values of the M mark displacements in the PPI plane from the optical axis, i.e. from point O ' ₃ . Therefore, they can be reset. After this operation, the point of intersection of the image of the strokes in the IS _M mark M, observed on the screen of the information display unit (for example, a monitor) 22, will visualize the position of the point O '' ₃ .

After the point of intersection of two strokes of mark M on the optical axis is drawn, the displacement of mark M is carried out in the PPI plane in two mutually perpendicular directions by means of linear carriages 8 and 9, and at the same time, on the screen of the information display unit (for example, a monitor), 22 displacements of the strokes of the IS _m mark M. As a result of these displacements of the brand M, the intersection of the intersection point of the images of its strokes with the distortions of the interference fringes is performed in the picture 31 displayed on the screen of the information display unit (e.g. ) 22. For the positions of those curvature of interference fringes that correspond to the selected characteristic points on the controlled aspherical surface 16, take readings for linear displacement sensors 28 and 29 on the digital display unit 30, the values of which reflect the values of the displacements of mark M in the PPI plane in two mutually perpendicular directions from the optical axis. Since the intermediate PPI plane, optically conjugated to the aspherical surface 16, is in its physical nature perpendicular to the optical axis, and the M mark is displaced by linear carriages 8 and 9 in parallel with the ox axis and the oy axis of the oxyz rectangular coordinate system, the values of the M mark displacements in the plane PPI can be expressed in terms of the coordinates of the rectangular coordinate system o'x'y'z ', the center o' of which is located on the optical axis and aligned with the point O ' ₃ , the axis o'z' is aligned with the axis oz of the coordinate system oxyz, and the axis o ' x 'and o'u' lie in the PPI plane, are parallel to the axes oh and oy of the oxyz coordinate system, respectively, and are directed with them in the same direction. In this regard, the rectangular coordinate system o'x'y'z 'is also right.

Thus, for each selected characteristic point i on the aspherical surface 16 of the optical part 17, the coordinates (x ' _{npi i} , y' _{npi i} ) of the corresponding point in the plane of the intermediate PPI image optically conjugated with the aspherical surface 16 will be measured. These coordinates are the coordinates intermediate image of the aspherical surface 16 of the optical part 17 located in the PPI plane, which is formed in the reverse direction of the rays reflected from the aspherical surface 16 by means of a synthesized holograph we canceller 13 and the first focusing lens 10. The measured coordinates (x _{'PTP i,} y' _{PTP i)} are the coordinates (x _{ap i,} y _{Apt i)} the selected feature point i on controlled aspherical surface 16. To carry out this operation, to establish a relationship between the coordinates of the points of the aspherical surface 16 of the optical part 17 with the coordinates of the corresponding points in the PPI plane.

Since the aspherical surface 16 is axisymmetric, the connection of the abscissa x _{ap i} for the point i on the aspherical surface 16 with the abscissa x ' _{ppi i of the} corresponding point in the PPI plane will be similar to the relation of the ordinate y _{ap i} on the aspherical surface 16 with the ordinate y' _{ppi i} in plane PPI. Therefore, it is enough to establish this connection for the ordinates y an _i and y ' _{npi i} . In the optical circuit shown in FIG. 1, the path of the extreme GABE ray emerging from the afocal system 2 and passing through point G in the PPI plane, through point A, is the focus of the first focusing lens 10, through point B at the edge of the hologram-compensator 13 and incident at point E in the aspheric edge zone the surface 16 of the optical part 17. In the range of this beam between the first focusing lens 10 and the synthesized hologram compensator 13, the relation

where y ' _{npi g} is the ordinate of the point G in the PPI plane, h _{gk e} is the height at which the ray at point B falls on the compensator hologram 13. Based on this equality, we can write a similar relation for the ordinate y' _{npi i of} point i in the plane PPI associated with its corresponding point on the hologram compensator 13

where h _{gk i} is the height of the point of incidence on the hologram-compensator 13 of the beam passing in the PPI plane through the point with the ordinate y ' _{ppi i} . After diffraction by the hologram 13, it will fall on the aspherical surface 16 at the point with the ordinate y _{aп i} . To determine this ordinate, you can use the data obtained for the case of calculating the path of rays from an aspherical surface 16 along its normals to the hologram-compensator 13. To do this, set a number of points located on the profile of the aspherical surface 16 from its tip O ₃ to the edge of the light diameter of the optical part 17 with a given interval Δy changes the ordinate y points of this series, and is found using well-known programs for calculating optical systems (for example, OPAL, DEMOS, ZEMAX) for each ordinate y _{ap n} = y _{ap n-1} + Δy values s of heights h _{gk n} on the hologram-compensator 13. Then, according to formula (3), for each height h _{hk n} , the ordinate y ' _{npi n is found} in the PPI plane. The obtained calculated data is summarized in a table of the form Table 1. When controlling the aspherical surface during the analysis of this table, the closest value y ' _{npi n} to the measured y' _{npi i} is found in the fourth column and the corresponding y y _{n n} value is determined in the second column, which is taken of _Apt ordinate y _i on the aspherical surface 16. it is obvious that the error value thus found _an y _i is less than half the selected step width Δy change ordinate y aspherical surface 16. this implies that the error op edeleniya _an ordinate y _i is the smaller, the smaller the selected step change Δy ordinate y when calculating values for the columns of Table 1 (For the same table can be determined and the values of the abscissa x _i of defects on _an aspheric surface at the measured abscissa x _'i in the plane of the _claims PPI.

Therefore, the expressions for the abscissas of the selected points on the profile of a given aspherical surface are also given in parentheses in the columns of this table.). In practice, Δy can be set to a value less than 1 mm; therefore, the error in determining the ordinate y _{ap i} defect on the aspherical surface 16 will be fractions of a millimeter. Since the proposed device can be used with high-precision linear displacement sensors of the brand M, and the step Δy in calculating the values of Table 1 can be chosen small enough (a tenth of a millimeter or even less), the proposed device can really provide increased accuracy of control of defect positions on aspherical surfaces . In addition, this device improves the accuracy of control of defect positions on aspherical surfaces by eliminating the influence of distortion introduced by the synthesized compensator hologram. This is achieved due to the fact that when controlling an aspherical surface, the coordinates of defects in the intermediate image of the aspherical surface distorted by distortion are first measured using the M mark, and then the true (free from distortion) coordinates of defects on the aspherical surface are found in Table 1.

The proposed device (see Fig. 2) for determining the positions of defects on the aspherical surface of the optical part operates as follows. The beam of light rays from a monochromatic (laser) light source 1 enters the afocal system 2 and is converted by it into an expanded parallel beam of rays, which passes through the first mark M1, enters the beam splitter 3, where it partially passes and is partially reflected by it. The reflected part of the beam of rays enters the reference branch of the device falls onto a flat reference mirror 4, oriented perpendicular to the rays of this beam, is reflected from it and partially reflects from the beam splitter 3 in the auto-collimation course and partially passes through it. The reflected part of the reference beam of rays passes in the reverse direction the first mark M1, the afocal system 2 and falls into the hole of the output window of the light source 1, and the transmitted beam splitter 3 part of the reference beam of rays enters the receiving part, where it is reflected from the flat rotary mirror 18, passes the second mark M2 and enters the second focusing lens 19, which focuses at the point A _o serving as a reference point in the device. Then this part of the reference beam of rays passes through the lens of the photodetector device (for example, a digital video camera) 20 and falls on the registration plane 21 of the photosensitive elements of the photodetector device (for example, a digital video camera) 20.

The object beam of the device receives the transmitted beam splitter 3 of the parallel beam of rays emerging from the afocal system 2 and passing the first mark M1. The beam of rays arriving at the object branch passes through the first focusing lens 10, transforming it into a converging homocentric beam of light rays centered in the form of a luminous point A in the rear focus of the lens 10, passes through the diaphragm 11 located in the rear focal plane of the lens 10, and falls on the synthesized hologram optical element 12 in the form of a diverging homocentric beam of light rays, illuminating the hologram-compensator 13 and quotation holograms 14 and 15. The hologram-compensator 13 in the process of diffraction of light on it s rays transmitted light forms an axisymmetric light beam, each beam which is incident on the aspherical surface 16 of the optical member 17 to its respective specific normal of that surface and is reflected from it in the opposite direction. In this case, the reflective aspherical surface 16 of the optical part 17 acts as an object. Reflected from surface 16 of the aspherical light beam in the course of autocollimation propagates to the hologram-compensator 13, and as a result of diffraction on it focuses to a point A _'16 which is autocollimation image luminous point A. Then, the light beam passes in the reverse direction and the diaphragm 11 is converted by the first focusing lens 10 into a parallel beam of rays, which the beam splitter 3 is divided into two beam of rays. One of them (the past beam splitter 3) passes the first mark M1, the afocal system 2 and enters the opening of the output window of the monochromatic light source 1. Another beam of rays (reflected from the beam splitter 3) enters the receiving part, where it is reflected from the plane rotary mirror 18, passes the second brand M2, the second focusing lens 19 passes, focusing it to the point A '' ₁₆ , the lens of the photodetector device (for example, a digital video camera) 20 passes and falls onto the registration plane 21 of the photosensitive elements of the photodetector devices (for example, a digital video camera) 20. During each of these two beams of rays, an intermediate image of the aspherical surface 16 of the optical part 17 is formed through the synthesized hologram-compensator 13 and the first focusing lens 10. Thus, two intermediate images of the aspherical surface are present in this device 16 of the optical part 17, one of which is located between the afocal system 2 and the beam splitter 3 and corresponds to the plane of the intermediate image PPI1, and the other in the receiving part between the flat rotary mirror 18 and the second focusing lens 19. It corresponds to the plane of the intermediate image PPI2. In this case, both in the PPI1 plane and in the PPI2 plane, an inverse image of the aspherical surface 16 of the optical part 17 is formed. The planes PPI1 and PPI2 are optically conjugated with the aspherical surface 16 of the optical part 17. In this regard, the point O ′ _{3 1} in the plane of the intermediate image PPI1, lying in the center of the intermediate image of the aspherical surface 16 of the optical part 17 and, accordingly, on the optical axis, is optically conjugated to the vertex O _{3 of the} aspherical surface 16 of the optical part 17 and is its image. The point G ₁ lying in the plane of the intermediate image PPI1 is optically conjugated to the point E located near the boundary of the aspherical surface 16 of the optical part 17, and is its image. In the same way, the points O ′ _{3 2} and G ₂ in the plane of the intermediate image PPI2 are optically conjugated to the points O ₃ and E of the aspherical surface 16, respectively, and are their images. With the planes of the intermediate images PPI1 and PPI2, the alignment planes of the strokes of the marks M1 and M2, respectively, are combined. Obviously, in this case, in the planes PPI1 and PPI2, in the reverse ray path from the aspherical surface 16 of the optical part 17, images of the first brand M1 will be formed. Thus, in the plane of the intermediate image PPI2 are the second mark M2 and the image of the first mark M1.

By means of the second focusing lens 19 and the lens of the photodetector (for example, a digital video camera) 20, an inverse intermediate image formed on the PPI2 plane of the aspherical surface 16 of the optical part 17 is projected onto the registration plane 21 of the photodetector (for example, a digital video camera). As a result, in the registration plane 21, a final image of the aspherical surface 16 of the optical part 17 is formed, which is straight. Images of strokes of marks M1 and M2 are also projected onto the same registration plane 21. As a result of the combination in the receiving part of the light beams coming from the reference and object branches, and the resulting interference of the corresponding light waves, an interference pattern is formed for the aspherical surface 16 of the optical part 17, which is also displayed in the registration plane 21. the image of the aspherical surface 16 of the optical part 17 together with the image of this interference pattern, as well as the images of strokes of the marks M1 and M2 are transmitted to the photodetector (e.g., digital camera) 20 to the screen unit information display (e.g., monitor) 21, where 31 - the final image aspherical surface 16 of the optical part 17 with its corresponding interference pattern ISH _m1 and ISH _m2 - Image strokes marks respectively M1 and M2. On the screen of the information display unit (for example, a monitor) 22, the point O ″ ₃ is located at the center of the image 31 of the aspherical surface 16 and the interference pattern for this surface. In this regard, it corresponds to point O ' _{3 1} in the plane of the intermediate image PPI1, point O' _{3 2} in the plane of the intermediate image PPI2 of the aspherical surface 16 of the optical part 17 and point O ₃ - the top of the aspherical surface 16 of the optical part 17. On the screen of the display unit information (for example, a monitor) 22 shows the interference pattern in the form of segments of interference fringes in the annular zone 32 surrounding the interference pattern 31. It corresponds to an alignment auto-collimation hologram 14 intended for monitoring the installation of the synthesized hologram optical element 12 relative to the luminous point A.

In order to conveniently and clearly identify defects and determine their location on a controlled aspherical surface 16, it is necessary that on the screen of the information display unit (for example, a monitor) 22 a direct image of the aspherical surface 16 of the optical part 17 is formed. For this, the body of the photodetector device (for example, a digital video camera) 20 rotate 180 ° around its optical axis relative to the initial working position of the photodetector (for example, a digital video camera) 20.

Defects on the controlled aspherical surface 16 of the optical part 17 are determined by visual analysis of the interference pattern present on the final image 31 of this aspherical surface 16 on the screen of the information display unit (for example, a monitor) 22. Defects and their positions on the controlled aspherical surface 16 are visualized by curvature of the stripes in this interference picture. From the curvature of the interference fringes, characteristic points are selected on the controlled aspherical surface 16, to which the greatest defects correspond and which must be eliminated first of all. Then, the positions of these characteristic defective points on the controlled aspherical surface 16 relative to its apex are determined, similar to the way it is done when using a variant of the device, the optical scheme of which is shown in FIG. 1. This imaging position of the point O '' on the screen ₃ displaying information block (e.g., monitor) 22 is performed using ISH marks _m1 M1 lines of the image. To do this, move the brand M1 in the plane of the intermediate image PPI1 of the aspherical surface 16 by means of linear carriages 8 and 9 and combine the point of intersection of the shadows of its two strokes with the luminous reference point A _rep . The output control on the optical axis of the point of intersection of two strokes of mark M1 is carried out by observing, for example, in a magnifying glass from the side of the aspherical surface 16, the intersection of the point of intersection of their shadows with the luminous reference point A _rep located on the optical axis. (To carry out this operation, part 17 is temporarily removed from the control circuit and then returned back) For this position of the M1 mark, the intersection point of images of its strokes on the screen of the information display unit (for example, a monitor) 22 will be aligned with point O '' ₃ . Then the M2 mark is moved in the plane of the intermediate image PPI2 of the aspherical surface 16 by means of linear carriages 36 and 37 and the image of its ISh _m2 strokes with the image of ISh _m2 strokes of the first mark M1 are combined on the screen of the information display unit (for example, a monitor) 22. After that, the readings for the coordinates x ' _{ppi i} and y' _{ppi i} are reset to zero on the digital display units 30 and 45 and begin to measure the coordinates of the characteristic points on the aspherical surface 16, similar to that described above for the device whose optical diagram is shown in FIG. one.

When monitoring aspherical surfaces in which only axisymmetric defects are present at the forming stages, it is sufficient to measure with the proposed device one of the coordinates of the defects: x or y depending on how the interference strips are oriented on the aspherical surface: along the axis ox or the axis oy right rectangular coordinate system oxyz, the center of which is located at the vertex O _{3 of the} aspherical surface 16, and the axis oz coincides with the axis of symmetry of the aspherical surface 16 (see Fig. 1, Fig. 2).

The operability of the proposed device was tested on the example of a variant of the device with the principal optical circuit depicted in FIG. 2. The following are the results of the control of the proposed device on an aspherical surface, on which only axisymmetric defects were present during its shaping. The equation of this aspherical surface has the form: z = 0.036643y ² /(1+(1+0.000331y ² ) ^½ ). The radius of curvature R ₀ at the apex of a given aspherical surface is 27.29 mm, and its conical constant K is -1.246446. The total and light diameters of the optical part with this aspherical surface are 32 and 30 mm, respectively. When monitoring this aspherical surface in the proposed device (Fig. 2), a laser with radiation at a wavelength λ equal to 0.6328 μm was used as a light source, and micrometric screws with scales with a price were used as drives and linear displacement sensors and digital indication blocks scale divisions for an accurate reading of 0.01 mm.

In FIG. 3 and FIG. Figure 4 shows the images 31 of the aspherical surface 16 observed along with the interference pattern recorded on the screen of the information display unit (for example, a monitor) 22 and recorded by a photodetector device (for example, a digital video camera) 20, obtained by monitoring the above aspherical surface. In addition, in FIG. 3 and FIG. 4 there are images of the interference pattern in the form of segments of interference fringes in the annular zone 32, which corresponds to the autocollimation alignment hologram 14, as well as strokes of the ISh _m1 and ISh _m2 marks, respectively, M1 and M2.

In FIG. 3, the image 31 of the controlled aspherical surface 16 together with the interference pattern is recorded at the initial stage, and in FIG. 4 - at the finishing stage of polishing this aspherical surface. The interference fringes in these interference patterns are obtained by rotating the controlled part 17 about the axis oX of the right-angled coordinate system oxyz (see Fig. 2), in which the equation of the controlled aspherical surface 16 is written. In this case, the rotation of the part 17 is chosen so that the direction of curvature of the interference fringes upward in these interference patterns corresponded to the direction towards the tops of the tubercles at the defects located on a controlled aspherical surface 16. The indicated interference setting the radiation pattern was visually controlled on the screen of the information display unit (for example, a monitor) 22, where, as noted above, a direct image 31 of the aspherical surface 16 was obtained together with the interference pattern.

In FIG. 3 and FIG. 4 shows that the strokes in ISh _m1 and ISh _{m2 of} each brand M1 and M2 intersect at an angle of 90 °. In this case, the image of the strokes of these brands, directed from left to right, are parallel to each other and coincide. Brand M1 in this embodiment of the proposed device (see Fig. 2) is located between the afocal system 2 and the beam splitter 3 and is aligned with the plane of the intermediate image PPI1, in which it is set so that the intersection point of its strokes is displayed on the optical axis and aligned with the point O ' _{3 1} optically conjugated with the vertex O _{3 of the} controlled aspherical surface 16. In this case, the intersection point of the stroke images in ISh _m1 will be aligned with the point O'' ₃ located on the screen of the information display unit (for example, a monitor ora) 22 and a controlled aspherical surface 16. Optically conjugated with the vertex O _3. Therefore, the point of intersection of the images of the strokes in ISh _m1 in FIG. 3 and FIG. 4 is located in the center of the image 31 of the controlled aspherical surface 16 together with the interference pattern. Therefore, it is used in this particular case (when axisymmetric errors are present on the controlled aspherical surface 16) only to visualize the position of this center in order to control the output of the M2 mark intersection point on the optical axis, which is located in the receiving part of the proposed device (see Fig. 2 ) between the flat rotary mirror 18 and the second focusing lens 19. In this case, the plane of arrangement of the strokes of the M2 brand is aligned with the plane of the intermediate image PPI2 of the controlled asf of the surface 16. In this plane are the axes o'x 'and o'y' of the right-angled coordinate system o'x'y'z ', the origin of coordinates o' of which is located on the optical axis and is aligned with the point O ' _{3 2} , optically conjugated with the apex O _{3 of the} aspherical surface 16, and the axis o'x 'is perpendicular to the plane of the figure depicted in FIG. 2. Using the M2 mark, defect positions are determined on the controlled aspherical surface 16. For this, the intersection point of the M2 mark strokes is displayed on the optical axis in the receiving part of the proposed device by moving it in the plane of the intermediate image PPI2 using the linear carriage 36 along the o'x axis ', and by means of the linear carriage 37 along the axis o'y'. This state is monitored by combining images of strokes ISh _m1 and ISh _{m2 of} marks M1 and M2 on the screen of the information display unit (for example, a monitor) 22. The values on the microscrew scales of linear carriages 36 and 37 for this state serve as a reference when measuring the values of the displacements of the mark M2 from the optical axis in the plane of the intermediate image PPI2 when determining the positions of defects on the aspherical surface 16. Since only axisymmetric defects were present on the controlled aspherical surface 16, using M2 arch controlled bottom position for each selected (characteristic) pits and mounds position characteristic peaks present on the aspherical surface defects. To do this, she moved through the linear carriage 36 along the o'x 'axis (Fig. 2) until the intersection of the points of intersection of her strokes with the point corresponding in the plane of the intermediate image PPI2 to the bottom of each selected hole and the top of each selected hillock. These alignments were controlled visually on the screen of the information display unit (for example, a monitor) 22 by combining the intersection point of the strokes in ISh _{m2 of} brand M2 with the visualized interference pattern with the bottom of each selected hole and the top of each selected hill (see Fig. 3 and Fig. 4) . For each position of the M2 mark, in the process of combining the point of intersection of its strokes with the point corresponding in the PPI2 plane to the bottom of the selected hole and the top of the selected hillock, readings were taken on the micrometer screw scale, which then determined the displacements of the M2 mark from the optical axis, i.e. from the origin o '. Thus, the measured values of the M2 mark displacements are the coordinates x 'of the points in the plane of the intermediate image PPI2, corresponding to the x coordinates of the bottom positions of each selected pit and the vertices of each selected hillock on a controlled aspherical surface 16. Next, the x coordinates of the bottom positions of each of the selected hole and the top of each selected hillock using Table 2 calculated for this, similar to Table 1. Step Δx changes the x coordinate on the profile of the controlled aspherical surface in the calculation of Table 2 was chosen equal to 0.2 mm.

In FIG. 3 (a) and FIG. 3 (c) the intersection point of the strokes in ISh _m2 is located in the area of the bottom of each of the two holes present on the aspherical surface visualized by the interference pattern. They correspond to the values of the measured coordinates x 'in the plane of the intermediate image PPI2, equal to -1.02 and - 4.23 mm. According to these data, using Table 2, we determined the x-coordinate values of the corresponding points on a controlled aspherical surface, which are equal to: 3.20 and 13.50 mm.

In FIG. 3 (b) and FIG. 3 (d) the intersection point of the strokes in ISh _m2 is located on the vertices of two hillocks visualized by the interference pattern. They correspond to the values of the measured coordinates x 'in the plane of the intermediate image PPI2, equal to - 3.17 and - 4.67 mm. According to these data, using Table 2, the x-coordinate values of the corresponding points on the controlled aspherical surface were determined, which are 10.00 and 14.80 mm.

In FIG. 4 (a), FIG. 4 (c) and FIG. 4 (d) the intersection point of the strokes in ISh _m2 is located on the vertices of three hillocks visualized by the interference pattern. They correspond to the values of the measured coordinates x 'in the plane of the intermediate image PPI2, equal to - 0.62, - 3.61 and - 4.77 mm. According to these data, using Table 2, we determined the coordinates x of the corresponding points on the controlled aspherical surface, which are equal to 1.95, 11.45 and 15.10 mm.

In FIG. 4 (b) and FIG. 4 (d) the intersection point of the strokes in ISh _m2 is located in the zone of the bottom of each of the two holes present on the aspherical surface visualized by the interference pattern. They correspond to the values of the measured coordinates x 'in the plane of the intermediate image PPI2, equal to - 2.98 and - 3.88 mm. According to these data, using Table 2, we determined the coordinates x of the corresponding points on a controlled aspherical surface, which are 9.40 and 12.25 mm.

As indicated above in FIG. 4 (d), the position of the intersection point of the strokes in ISh _m2 corresponds to a point with an x coordinate of 15.10 mm on a controlled aspherical surface 16. This means that the working area of the aspherical surface 16 is fully disclosed, because the light diameter of the optical part 17 is 30 mm.

It follows from the experimental data that the coordinates of the defects on a controlled aspherical surface are determined to within hundredths of a millimeter. As mentioned above, this accuracy can be improved by using high-precision linear displacement sensors for linear carriages, as well as by decreasing the step Δy (or Δx) of changing the coordinate y (or x) in the calculation of Table 1. In addition, an additional contribution to improving the accuracy of determination the coordinates of defects on an aspherical surface by the proposed device is ensured by eliminating the influence of distortion of the synthesized hologram compensator on the process of determining these coordinates.

Due to the fact that the synthesized hologram compensator used in the proposed device can be manufactured to control aspherical surfaces of both second and higher order (see Larionov N.P. Methods and means of controlling the shape of aspherical surfaces of large and high-aperture optical elements based on the use of axial synthesized holograms. Kazan, 2002, pp. 40-45 - dissertation for the degree of candidate of technical sciences), then on the basis of the above data it follows that the proposal read only allows device to provide control of such surfaces with high precision.

Claims (4)

1. A device for determining the positions of defects on the aspherical surface of an optical component, comprising a monochromatic light source and an afocal system sequentially installed along the path of light rays, a beam splitter for forming the support and object branches and a receiving part, installed in the object branch along the path of light rays propagating from the beam splitter , the first focusing lens for forming a converging homocentric beam of light rays with a luminous point in its back focus, is synthesized A hologram optical element consisting of three axial coaxial synthesized holograms, one of which is a compensating hologram, and the other two holograms are alignment, a flat reference mirror mounted in the reference branch perpendicular to the light rays propagating from the beam splitter installed in the receiving parts along the light rays propagating from the beam splitter, a second focusing lens, a photodetector and an information display unit, characterized in that the construction additionally contains a mark with two intersecting strokes located between the beam splitter and the first focusing lens and combined with an intermediate image of the aspherical surface of the optical part, the mark is fixed in a node equipped with an angular rotation mechanism for angular orientation of the mark and three linear carriages to enable brand displacements in three mutually perpendicular directions, one of which is perpendicular to the plane of its strokes, for which each linear carriage is equipped with a drive connected to the drive control unit, to ensure the possibility of measuring the magnitude of the displacement of the brand, each linear carriage is equipped with a linear displacement sensor connected to the input of the digital display unit, a flat rotary mirror is installed in the receiving part after the light beams after the beam splitter, the focal plane of the first focusing lens mounted aperture. 2. A device for determining the positions of defects on the aspherical surface of an optical part according to claim 1, characterized in that both dashes of the mark intersect each other at an angle of 90 degrees and each of them is oriented parallel to one of the two directions of the mark’s displacement, parallel to the plane of intersection between two strokes. 3. A device for determining the positions of defects on an aspherical surface of an optical component, comprising a monochromatic light source and an afocal system sequentially installed along the path of light rays, a beam splitter for forming the support and object branches and a receiving part, installed in the object branch along the path of light rays propagating from the beam splitter , the first focusing lens for forming a converging homocentric beam of light rays with a luminous point in its back focus, is synthesized A hologram optical element consisting of three axial coaxial synthesized holograms, one of which is a compensating hologram, and the other two holograms are quoted, a flat reference mirror mounted in the reference branch perpendicular to the light rays propagating from the beam splitter installed in the receiving parts along the light rays propagating from the beam splitter, a second focusing lens, a photodetector and an information display unit, characterized in that the construction additionally contains a first mark with two intersecting strokes located between the afocal system and the beam splitter and combined with the first intermediate image of the aspherical surface of the optical part, while the first mark is fixed in the first node, equipped with an angular rotation mechanism for the angular orientation of the first mark and three linear carriages to make it possible to displace the first mark in three mutually perpendicular directions, one of which is perpendicular to the plane the location of its strokes, for which each linear carriage is equipped with a drive connected to the first drive control unit, to enable measurement of the displacement of the first mark, each linear carriage is equipped with a linear displacement sensor connected to the input of the first digital display unit, in the receiving part along the light rays a flat rotary mirror is installed after the beam splitter, a second mark is introduced with two intersecting strokes, which is combined with the second intermediate image m of the aspherical surface of the optical part and is fixed in the second node, equipped with an angular rotation mechanism for angular orientation of the second mark and three linear carriages to enable the second mark to be displaced in three mutually perpendicular directions, one of which is perpendicular to the plane of its strokes, for which each linear the carriage is equipped with a drive connected to the second drive control unit, for each linear carriage to be able to measure the displacement of the second mark As it is equipped with a linear displacement sensor connected to the input of the second digital indication unit, an aperture is installed in the rear focal plane of the first focusing lens. 4. A device for determining the positions of defects on the aspherical surface of an optical part according to claim 3, characterized in that both dashes of each mark intersect each other at an angle of 90 degrees and each of them is oriented parallel to one of two directions of displacement of the corresponding mark parallel to the plane the location of two strokes intersecting each other.

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