KR102115544B1 - Gap Filling Type Micro Lens Array To Improve Homogeneity And Efficiency - Google Patents

Abstract

z : 단일 렌즈의 X,Y 위치에 대한 높이값(새그값)
c : 단일 렌즈의 축별 곡률 (x-curvature, y-curvature
κ: 단일 렌즈의 비구면 계수 (conic constant)

식(2)
S_sub=(S_base ·Z_sub)/Z_base
S_sub : 기본 렌즈의 최대 피치값(최대 직경)
S_base : 서브 렌즈의 최대 피치값(최대 직경)
Z_sub : 기본 렌즈의 새그값
Z_base : 서브 렌즈의 새그값The present invention is a gap-filling type microlens array, which is arranged on one side of the optical substrate by being divided into a basic lens and a sub-lens, wherein the basic lens and the sub-lens are the same as any one of polygonal, circular, elliptical, or irregular shapes. Or a heterogeneous, aspherical shape satisfying the sag profile of the following formula (1), wherein the basic lens and sub-lens have the same pitch size and the ratio of the sag value as in the following formula (2), The primary lenses are randomly arranged, and there are overlapping portions between adjacent primary lenses, and the maximum length in the x and y-axis directions of the openings between the primary lenses is 1 to 20% of the maximum pitch size in the x and y-axis directions, and the The sub-lens is arranged in the opening, and the maximum length in the x- and y-axis directions of the overlapping portions of the adjacent primary lens and the sub-lens is 1 to 20% of the maximum pitch size in the x and y-axis directions of the sub lens. It relates to a peeling type microlens array.
Expression (1)

z: Height value for X, Y position of a single lens (sag value)
c: Axial curvature of a single lens (x-curvature, y-curvature
κ: single lens conic constant

Expression (2)
S _sub = (S _{baseZ sub} ) / Z _base
S _sub : The maximum pitch value (maximum diameter) of the basic lens
S _base : Sub-lens maximum pitch value (maximum diameter)
Z _sub : Sag value of basic lens
Z _base : Sag value of sub lens

Description

Gap Filling Type Micro Lens Array To Improve Homogeneity And Efficiency}

The present invention relates to a gap-filling type microlens array for improving the homogeneity and efficiency of operation in combination with an arbitrary light source, which is divided into a primary lens and a sub-lens, and overlaps a portion by random and random alignment of the basic lens and In the non-overlapping opening, it relates to a gap-filling type micro lens array for improving homogeneity and efficiency characterized by filling the opening with a sub-lens having a small size of the same shape.

Homogeneity of the laser beam is an important issue not only in various fields of laser material processing, but also in laser measurement technology and analysis. The laser beam homogenization technique generally uses a diffractive optical element (DOE) having a complex phase function, an aspheric lens, a polygon homogenized rod, and micro optic-element groups. Aspherical lenses and diffractive optical elements (DOEs) are commonly used to generate flat top distributions in Gaussian light sources.

However, these optical elements have a very small tolerance range in the alignment state of the incident light. In order to overcome the above weakness, a polygon homogenized rod is an element that generates high transmittance and uniformly distributed output light, and is recognized as a substitute for generating a planar distribution while transmitting light from one point to another. Shaping performance using polygon homogenized rods is independent of incident intensity distribution. However, the transmission efficiency is lower than that of other optical elements.

In general, Micro-Lens Array (MLA) is suitable for solving the above-mentioned limitations of phase function, aspheric lens and polygonal homogeneous rod. In addition, compared to a diffraction optical element (DOE), since the micro-lens array (MLA) has less stray light and no zero diffraction order, intensity within a desired output image There is a great advantage in distributing it.

First, a micro-lens array (MLA) is less sensitive to the wavelength of incident light, such as a laser source. Second, such a system can be easily operated in the entrance intensity profile and phase. It is easy to use in vertical surface emitting laser (VCSEL) as well as laser diode (LD).

The small size of the optical package can be achieved because no additional optical elements are required. Finally, due to the principle of refraction of the microlens array, the MLA system provides very high efficiency and satisfies large illumination angles.

Figure 1 relates to the measured intensity distribution of the output beam through the MLA (a) LD, (b) relates to the normal array MLA of the VCSEL. Recently, the microlens array system is composed of VCSEL and regular array MLA. However, the regular array MLA generates horizontal and vertical stripe noise in the VCSEL due to the structure of the periodic MLA. This phenomenon creates unwanted sharp intensity peaks even when LD is applied as a light source. The striped and sharp intensity peaks are factors perceived by the sensor module as noise.

For the above problems, randomly distributed MLA, such as randomly arranged MLA, is commonly used in many fields of micro optics. FIG. 1 relates to the measured intensity distribution of the output beam through the MLA, and is a diagram of (c) LD and (d) VCSEL random array MLA.

Usually, the randomly distributed MLA is aperiodic due to the arbitrary position of the unit lens. Consequently, the distribution of output intensity has a high uniformity. However, the randomly distributed microlens array structure reduces the efficiency by about 30% compared to normal MLA. Therefore, in order to use the randomly distributed MLA, it is necessary to overcome the height difference between the unit lenses and a low filling rate.

WO2017 / 204748 (Microlens Array Diffusers) is a product that the individual lenses are randomly arranged within a certain range based on the almost identical lens size where the positions of the individual lenses are rather regular, and the performance of each individual lens is different, not a block type arrangement. The repeatability problem may occur, and it is difficult to optimize the redesign and additional performance due to the complexity of the design.

In order to solve the above problems, an object of the present invention is to fill a gap filling type micro lens array that fills an empty space that is a non-overlapping opening of a randomly arranged primary lens with a sub-lens to improve homogeneity and maintain efficiency. To provide.

Another object of the present invention is to provide a gap-filling micro-lens array that improves homogeneity and improves efficiency by 30% compared to a randomly arranged MLA, compared to a conventional regular array MLA.

In order to achieve the above object, the present invention is a gap-filling type microlens array that is divided and arranged into a primary lens and a sub-lens on one surface of the optical substrate, wherein each of the base and sub-lenses has a polygonal bottom shape, Either circular, elliptical, or irregular, homogeneous or heterogeneous, and the aspherical shape satisfying the sag profile of Equation (1) below. The ratio of the sag value is the same, the basic lenses are randomly arranged, and there are overlapping portions between adjacent basic lenses, and the maximum length in the X and Y axes of the openings between the basic lenses is the maximum pitch in the X and Y axes of the basic lenses. 1 to 20% of the size, and the sub-lens is disposed in the opening, and the maximum length in the X and Y axes of the portion overlapping with the adjacent primary lens and the sub lens is 1 of the maximum pitch size in the X and Y axes of the sub lens. It relates to a gap-filling type microlens array characterized by being ~ 20%.

Expression (1)

z: Height value for X, Y position of a single lens (sag value)

c: Axial curvature of a single lens (x-curvature, y-curvature)

κ: single lens conic constant

Expression (2)

S _sub = (S _{baseZ sub} ) / Z _base

S _sub : The maximum pitch value (maximum diameter) of the basic lens

S _base : Sub-lens maximum pitch value (maximum diameter)

Z _sub : Sag value of basic lens

Z _base : Sag value of sub lens

In addition, the present invention provides a gap-filling microlens array characterized in that the polygonal bottom of the basic lens and the sub-lens is rectangular or square.

In addition, the present invention provides a gap-filling type microlens array characterized in that the sag value of the overlapping portion of the same lens in the primary lens or the sub-lens is one of the overlapping primary lenses.

In addition, according to the present invention, the sag value of a portion in which the sag value of the sub lens is greater than the sag value of the basic lens in the overlapping portion of the basic lens and the sub lens has a sag value of the sub lens, and conversely, the sag value of the basic lens is A sag value of a portion larger than the sag value of provides a gap-filling microlens array characterized by having a sag value of the basic lens.

In addition, the present invention provides a gap-filling type microlens array characterized in that the opening of the primary lens is completely filled with the sub-lens and there is no remaining opening.

The present invention is a gap filling type micro lens array that fills an empty space, which is a non-overlapping opening of a randomly arranged primary lens, with a sub-lens. It works.

Another object of the present invention is to provide a gap-filling micro-lens array that improves homogeneity and improves efficiency by 30% compared to a randomly arranged MLA, compared to a conventional regular array MLA.

FIG. 1 relates to the measured intensity distribution of the output beam through the MLA (a) LD, (b) normal array MLA of VCSEL and (c) LD and (d) random array MLA of VCSEL.
Figure 2 relates to the gap-filling type microlens array of the present invention (a) is a 100% gap-filled design and (b) cross-sectional view by inserting a sub-lens.
3 is a view showing a cross-sectional shape when the base lens and the sub lens of the present invention overlap.
FIG. 4 is a sample of two types of designs, (a) a MLA with a randomly distributed primary lens, and (b) a MLA with a randomly distributed primary lens and an empty space filled by a sub-lens.
FIG. 5 is a diagram for output simulation of (a) the MLA in which the primary lens is randomly distributed, and (b) the MLA in which the primary lens is randomly distributed and the empty space is filled.
FIG. 6 shows the results of experiments of beam shaping and output intensity distribution of X and Y-axis profiles using VCSEL (a) MLA in which the primary lenses are regularly arranged (b) MLA in which the primary lenses are randomly distributed ( c) This is a diagram of an MLA in which an empty space of an MLA in which the primary lens is randomly distributed is filled with a sub-lens.
7 is a view showing a cross-sectional shape when the base lens and the sub lens of the present invention overlap.

Hereinafter, a preferred embodiment of the present invention will be described in detail. First, in describing the present invention, detailed descriptions of related known functions or configurations are omitted so as not to obscure the subject matter of the present invention.

As used herein, the terms 'about', 'substantially', etc. are used in the sense of or close to the numerical values when manufacturing and material tolerances unique to the stated meaning are presented, and to understand the present invention. To aid, accurate or absolute figures are used to prevent unscrupulous use of the disclosed disclosure by unscrupulous infringers.

The present invention is an optical substrate; And a gap-filling microlens array arranged on one side of the optical substrate and divided into a basic lens and a sub-lens,

Each of the base lens and the sub-lens has an aspherical shape in which each base shape is either a polygon, a circular shape, an elliptical shape, or an irregular shape, and sag profile of the following formula (1) is satisfied.

The polygon is preferably rectangular or square, but is not limited thereto.

Expression (1)

z: Height value for X, Y position of a single lens (sag value)

c: Axial curvature of a single lens (x-curvature, y-curvature)

κ: single lens conic constant

In addition, the ratio of the pitch size and the sag value of the basic lens and the sub-lens is the same as in the following equation (2).

Expression (2)

S _sub = (S _base × Z _sub ) / Z _base

S _sub : The maximum pitch value (maximum diameter) of the basic lens

S _base : Sub-lens maximum pitch value (maximum diameter)

Z _sub : Sag value of basic lens

Z _base : Sag value of sub lens

The primary lenses are randomly placed. However, the maximum length in the X and Y axis directions of the opening between the basic lenses is 1 to 20% of the maximum pitch size in the X and Y axis directions of the opening, and conversely, the basic lens X and 1 to 20 of the maximum pitch size in the Y axis direction. % Overlap may occur.

At this time, the sag value of the overlapping portion has a sag value of 1 time, not a sag value of 2 times. That is, the sag value of the overlapping portion of the same lens in the primary lens or the sub-lens is a value of any one of the overlapping primary lenses.

Subsequently, the sub lens is disposed in the opening. At this time, the maximum length in the X and Y axes of the portion overlapping the adjacent primary lens and the sub lens is limited to 1 to 20% of the maximum pitch size in the X and Y axes of the sub lens.

Basically, the basic lens has a random arrangement as shown in equation (3).

Expression (3)

P (i, j) = [P _x (i, j), P _y (i, j)],

P _x (i, j) = P _Rx (i, j) + rand ([-P _mx , P _mx ]) × D,

P _y (i, j) = P _Ry (i, j) + rand ([-P _my , P _my ]) × D,

Where i and j are the row and column indices, respectively, P (i, j) is the horizontal component P _x (i, j) and the vertical component P _y (i, j), respectively, and P _Ry (i, j) is The original coordinates of the primary lens for the regular array MLA, which is a continuous array with no openings and no overlapping parts, P _mx and P _my are the limits of the random coefficient, and D is the opening length ratio of the primary lens.

The D value may have 0.01 to 0.2, preferably 0.1 to 0.2, and in this case, the length of the maximum opening of the basic lens corresponds to 1 to 20% of the maximum pitch size in the x and y axes.

Figure 2 relates to the gap-filling type microlens array of the present invention (a) is a 100% gap-filled design and (b) cross-sectional view by inserting a sub-lens.

The present invention, the gap-filling type microlens array is designed by superimposing a randomly arranged sub-lens on a basic lens randomly arranged under the condition of equation (3). However, only one randomly distributed primary lens is designed, but the randomly distributed sub-lens is designed to fill all the empty openings between the primary lenses. That is, the sub-lens is inserted between the basic lenses, and eventually the sub-lenses are inserted into the openings between the basic lenses.

3 is a view showing a cross-sectional shape when the base lens and the sub lens of the present invention overlap.

The sag value of the overlapping portion of the primary lens and the sub-lens has the highest sag value. That is, the sag value of the overlapping portion of the same lens in the primary lens or the sub-lens is 1 time instead of 2 times, and the sag value of the sub-lens in the mutually overlapping portion of the primary lens and the sub-lens is greater than the sag value of the primary lens. The sag value of the portion has a sag value of the sub lens, and on the contrary, a sag value of the portion where the sag value of the basic lens is greater than the sag value of the sub lens has a sag value of the basic lens.

As a result, the opening of the primary lens is completely filled with the sub-lens so that there is no remaining opening.

The present invention can be produced using a two-photon polymerization (TPP) based on lithography technology. The primary lens is first printed in the entire active area, then the sub-lens is printed in the gap between the primary lenses. To simplify design and calculation, the structure of the basic lens and sub-lens of the present invention is analyzed in two directions (ie, X and Y axes). The structure of the gap filling microlens array of the present invention is designed in a direction to minimize the vignetting effect and height difference, which is a phenomenon in which the outer portion is darkened.

FIG. 4 is a sample produced with two types of designs, (a) is a microlens array in which the primary lenses are randomly distributed, and (b) is a microlens array in which the primary lenses are randomly dispersed and the openings are filled with sub-lenses. FIG. 5 is a diagram of an array output simulation of the structures (a) and (b) of FIG. 3.

4 (a) shows an empty space within 10 µm of the opening among the basic lenses, and the empty space does not serve as a lens. Therefore, light leaks through the empty space and a strong intensity is generated in the center. That is, as shown in Fig. 5 (a), the intensity distribution is measured with a Gaussian profile. On the other hand, Figure 4 (b) shows a 100% fill ratio in the active area and the height difference is minimized due to the sub-lens. Finally, the light beam does not pass but is refracted in the active area and uniformly dispersed in the target image, forming the top hat shape of Figure 5 (b). This means that the sub-lens can be inserted to control the luminosity within the active area.

FIG. 6 shows the results of beam shaping and output intensity distribution experiments of X and Y-axis profiles using VCSEL (a) MLA in which the primary lenses are regularly arranged (Comparative Example 1) (b) the primary lenses are random MLA dispersed (Comparative Example 2) (c) This is a diagram for an MLA (Example) in which the primary lens is randomly dispersed and the opening is filled with a sub-lens.

The three microlens arrays were placed on a VCSEL as a light source, operated, and then observed using a near infrared (NIR) camera.

The MLA in which the basic lenses of Comparative Example 1 were regularly arranged has reduced homogeneity in the target image as shown in FIG. 6 (a). More specifically, it can be seen that the relative intensity intensity of the cross section of the x-axis is not homogeneous at an angle O ~ ± 30 °.

Comparative Example 2 is a randomly distributed MLA of the basic lens to improve the phenomenon. As shown in Fig. 5 (b), it shows that the stripes of the shadow were removed from the picture taken by the near infrared (NIR) camera. This can be seen that the homogeneity of the relative strength intensity is improved than Comparative Example 1. However, overall, the relative intensity is low in the target image having an angle O to ± 30 ° compared to Comparative Example 1 and the example, thereby reducing the overall efficiency, and particularly passing through the diffusion of the beam of the VCSEL near the angle O °. Since the ratio is large, the relative intensity is greater than other angles. As a result, the profile of the target image was changed to a Gaussian distribution rather than a flat-top distribution.

In the embodiment corresponding to the present invention, FIG. 6 (c) complements the limitations of Comparative Examples 1 and 2, which are the two types of MLA. Looking at the relative intensity of the image, the efficiency is improved by about 30% compared to the randomly distributed MLA of Comparative Example 2. Eventually, a flat-top distribution that improves homogeneity appears by inserting a sub-lens into the opening of a randomly distributed primary lens. As a result, it is proved that the sub-lens is located in the opening of the empty space between the primary lenses and serves as a complementary lens.

6 is a view showing an example of various types of the basic lens and the sub-lens in the gap-filling type microlens array of the present invention. The feature of the present invention is that the random distribution of the basic lens and the overlapping portion between the basic lens and the opening, which is an empty space, are created, and the opening is filled with a sub-lens having the same shape as the basic lens but having a smaller size, which is less efficient than the comparative example. It is 30% improved and has the characteristic of securing the homogeneity of strength.

Therefore, even if the shapes of the undersides of the basic lens and the sub-lens are circular or other various shapes other than a square, the same effect may be generated by the random distribution and opening of the opening.

The present invention described above is not limited by the above-described embodiments and the accompanying drawings, and various substitutions, modifications and changes are possible within the scope of the present invention without departing from the technical spirit of the present invention. It will be obvious to those who have the knowledge of

Claims (5)

Optical substrates;
A gap-filling microlens array, which is divided into a basic lens and a sub-lens on one surface of the optical substrate,
The base lens and the sub-lens have an aspherical shape satisfying a sag profile of Equation (1) below, wherein each base shape is homogeneous or heterogeneous in one of polygonal, circular, elliptical, or irregular shapes.
The basic lens and the sub-lens have the same pitch size and sag ratio as shown in the following equation (2),
The basic lens is randomly placed by the following formula (3),
The basic lens has a portion overlapping with the adjacent basic lens by 1 to 20% of the maximum pitch size in the X and Y axes,
The maximum length of the opening between the basic lenses in the X and Y axes is 1 to 20% of the maximum pitch size of the basic lenses in the X and Y axes.
The sub-lens is disposed in the opening, and the maximum length in the X- and Y-axis directions of an overlapping portion of the adjacent primary lens and the sub-lens is 1 to 20% of the maximum pitch size in the X and Y-axis directions of the sub-lens, and the primary lens And the sag value of the overlapping portion of the sub-lens has the highest sag value.

Expression (1)

z: Height value for X, Y position of a single lens (sag value)
c: Axial curvature of a single lens (x-curvature, y-curvature)
κ: single lens conic constant

Expression (2)
S _sub = (S _base × Z _sub ) / Z _base
S _sub : The maximum pitch value (maximum diameter) of the basic lens
S _base : the maximum pitch value (maximum diameter) of the sub lens
Z _sub : Sag value of the main lens
Z _base : Sag value of sub lens

Expression (3)
P (i, j) = [P _x (i, j), P _y (i, j)],
P _x (i, j) = P _Rx (i, j) + rand ([-P _mx , P _mx ]) × D,
P _y (i, j) = P _Ry (i, j) + rand ([-P _my , P _my ]) × D,

i and j: row and column index, respectively
P (i, j): divided into horizontal component P _x (i, j) and vertical component P _y (i, j) respectively
P _Rx (i, j), P _Ry (i, j): represents the original coordinates of the primary lens for a regular array of MLAs, a continuous array with no openings and no overlapping parts, where P _mx and P _my are random coefficients Limit and D is the ratio of the opening length of the primary lens
D: 0.01 ~ 0.2
According to claim 1,
The gap filling type microlens array is characterized in that the base of the main lens and the sub lens has a polygonal bottom or a square.
According to claim 1,
The gap filling type microlens array characterized in that the sag value of the overlapping portion of the same lens in the primary lens or the sub-lens is one of the overlapping primary lenses.
delete According to claim 1,
The gap-filling microlens array is characterized in that the opening of the primary lens is completely filled with the sub-lens and there is no remaining opening.

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