RU2796277C2 - Three-coordinate target with double structure, optical measuring device and method using such target - Google Patents

Abstract

FIELD: three-coordinate measurement systems.

SUBSTANCE: group of inventions relates to a three-coordinate target 200, a three-coordinate measurement system, a system for three-coordinate optical measurement, and a method for three-coordinate optical measurement of the location of the first object relative to the second. The three-coordinate target, which can serve as a base for counting positions, contains on its working face 202: the first structure 210, which forms a flat base surface 212, divided at least into a first section 214, the surface of which has diffuse reflection properties, and a second section 216 , the surface of which has the properties of mirror reflection, and the second section 216 is divided into a number of local zones 217 located on the first section 214, and the second structure 220 containing an inclined surface 222, which is essentially flat and inclined relative to the specified flat base surface, while the inclined the surface contains relief elements or mirror elements that are distributed evenly over the sloped surface.

EFFECT: one measurement per exposure is provided.

28 cl, 6 dwg

Description

The field of technology to which the invention belongs

The present invention relates to the field of optical measurement of the relative position between a first object and a second object.

In particular, the invention relates to a three-dimensional measurement of the position of a first object relative to a second object. Measurements of this type are used in many areas in relation to linear and angular measurements, including, in particular, but not exclusively, the field of machining, in particular by means of a machining tool or other machining by removing material.

In the field of machining, there is a need to accurately know the position of the tool holder relative to the work holder in order to provide a machining range corresponding to the machining plan developed during machine setup.

The production of parts by means of machine modules (machining tool), in particular automatic lathes, automatic lathes, turn-mill centers, milling machines, machining centers and machine lines, usually contains three separate steps.

At the first stage of setting (or presetting), the operator (for example, the operator of a lathe) determines and checks on the machine module the machining plan, that is, the sequence of operations and axis offsets that are necessary to manufacture the required part on the machine. The operator acts carefully to obtain the most efficient machining plan, i.e. a plan that makes it possible to machine a given workpiece with a minimum of operations, while avoiding collisions between tools or with the workpiece. The operator selects the tool to be used and checks the quality of the resulting product, such as surface quality, tolerances, etc.

In the second manufacturing step, a series of parts are produced on a pre-configured machine module with the parameters that were determined during setup. This step is the only manufacturing step; it is often performed for 24 hours a day; while the machine module is fed with raw material by means of a feeder with a magazine or by means of a workpiece loader.

It may be that the production of a series of parts is interrupted, for example, to replace a worn tool, to manufacture parts of a different type on the same machine module, for machine maintenance, etc., and then the production is resumed. In this case, a preparation step is required to apply the settings that were previously defined during configuration. This stage of preparation is faster than setting up.

During this preparation, it is often necessary to replace the tool installed on the machine with another set of tools that is suitable for the upcoming processing. The positioning accuracy of this tool determines the quality of processing, but this positioning is difficult to reproduce at the next stages of preparation.

In addition, during the production phase, during the processing of new parts, especially over long periods of time, it is quite possible for the position of the tool holder relative to the workpiece holder to drift, in particular due to thermal expansion in machine tools.

State of the art

Therefore, in the machines of the current state of the art, various technical solutions have been proposed and are being proposed in order to guarantee the correct position of the tool holder relative to the workpiece holder at the manufacturing stage and at the preparation stage, that is, the correct relative position, which corresponds to the relative position of the tool holder and the workpiece holder, which was at the stage settings.

Many in situ measurement methods used in machine tools are designed to measure the relative position of the workpiece or workpiece holder and the tool itself. However, in this case, the measurement of the position of the workpiece or workpiece holder relative to the tool is affected by tool wear and thermal drift in the machine during this operation.

In addition, this type of relative position measurement, as a rule, is carried out in two coordinates, i.e. in two directions, as in DE 202016004237U.

Since such registration of the relative position of the workpiece or workpiece holder and the tool is limited to two coordinates (for example, Y and X, respectively, for the lateral and vertical directions), it does not have sufficient completeness to guarantee the correct relative position, so other means for measuring must be used. third coordinate (for example, Z - in the feed/retract direction of the work holder, also called "material direction"). In this situation, not only the cost of the measuring equipment increases, but also the time spent on implementation, which also adds an error due to the use of two measurement series at the same time.

US 2014362387 AA discloses an optical measurement device placed on a tool holder that makes it possible to check that the target object does not interfere with the tool holder. This optical measuring device uses a measuring element with several inclined parts to determine the geometric parameters of the laser measuring device, in particular the coordinate between the reflected beam sensor and the incident beam emitter. This measuring element is not involved in measuring the position of the tool holder relative to the target object, which may be the workpiece to be machined.

US 2010111630 AA discloses a tool repositioning system for a machine tool comprising irregularly shaped targets located on the tool, which allows precise optical measurement of the position of the tool by means of optical measuring elements whose position is not specified.

US 2007253002 AA discloses a system for optically measuring the distance between two bodies whose axes do not coincide, comprising, respectively, a radiating element and a receiving element located at the ends of both bodies.

US5831734 describes a technical solution in which an optical sensor is attached to a tool holder and registers the position of this tool holder relative to a workpiece that is to be machined and is provided with a distinguishable mark (groove).

US2014343890 proposes a hand-held (portable) device used as an aid in measuring the position of an object by means of a laser system. This portable device contains a three-coordinate target, which contains a base conical end with one working end surface containing visible fiducial marks, and a retroreflective reflector in the center.

US2004202364 presents a calibration object in the form of a prism, each face of which contains visible fiducial marks, and possibly a reference mark to identify the face in question.

However, these technical solutions do not allow determining the relative position of the workpiece to be processed and the tool in one exposure (one shooting act), so that one such exposure provides information that makes it possible to determine this relative position in three spatial coordinates.

Also, these technical solutions do not allow to ensure the independence of the parameters that change in real time during machining, in particular, tool wear and temperature of the tool and/or the working space of the machine, which receives the workpiece to be processed.

Disclosure of invention

One object of the present invention is to provide a technique that enables measurement of the position of a tool holder relative to a workpiece holder, and more generally, a measurement of the relative position of a first object and a second object, a technique that is free from the limitations of known measurement techniques.

Another objective of the present invention is to propose a technology that makes it possible to measure the position of the tool holder relative to the workpiece holder, and more generally, the measurement of the relative position of the first object and the second object, a technology that, in one exposure, determines the relative position of the first object and the second object in three coordinates.

According to the invention, this problem is solved, in particular, by means of a three-coordinate target, which can serve as a means for counting positions, containing on its working face:

• a first structure forming a flat base surface divided into at least:

- the first area whose surface has diffuse reflective properties, and

- a second section, the surface of which has specular reflection properties that differ from the first reflection parameters, and the second section is divided into a number of local zones located in the first section, and

• a second structure containing a surface that is inclined relative to the specified flat base surface. Such a device makes it possible to register the position of the target in three directions X, Y and Z, corresponding to the Cartesian coordinate system, and the target has a first structure or base surface parallel to the X, Y plane, and a second structure or inclined surface, which to a certain extent extends along the main direction Z.

According to another embodiment of the invention, said flat base surface is divided into at least:

- the first area, the surface of which has reflective properties in accordance with the first reflection parameters, and

- a second area, the surface of which has reflective properties in accordance with the second reflection parameters, which differ from the first reflection parameters.

According to one embodiment of the invention, the inclined surface comprises relief elements evenly distributed over it. According to another variant, the inclined surface contains mirror elements uniformly distributed over it. In both cases, the idea is to be able to register the position of an inclined surface, which is roughly flat, in the Z direction orthogonal to the reference surface. In order to accomplish this, in one case the elements of the relief form surface irregularities or small roughnesses; while the inclined surface, being rough, provides diffuse reflection, which allows the optical system that looks at the target to clearly see part of the inclined surface: in particular, these relief elements have a size of more than 700 nm, in particular more than 1 μm, namely, they have a size that is greater than the wavelength of the incident light, in this case visible light. Otherwise, inclined plane mirror elements arranged according to the geometry, such as mutually parallel lines located in the Z direction at different positions, are visually distinct from the rest of the inclined surface (which preferably exhibits diffuse reflection). Therefore, an optical system that looks at a target has the ability to clearly see a portion of the inclined surface with one or more mirror elements.

This three-coordinate target contains on its working face a double structure, respectively forming the first flat base (reference) surface and the second reference surface - a plane that is inclined relative to the first base surface. Such a spatial (three-coordinate) target geometry, along with the special and different optical characteristics of the surfaces that respectively form the first reference surface and the second reference surface, allows optical registration of the position of this target relative to the optical system used in the space of three dimensions X, Y and Z. According to In one embodiment, the optical system used makes it possible to carry out an optical position detection that actually ends with a measurement of the relative position through a single acquisition (exposure) step of both the first flat reference surface and the second inclined reference surface: thus, the measurement consists in simultaneously capturing an image a first flat reference surface and a second inclined reference surface. Such simultaneous shooting can be done in two, three, or more iterations, even n exposures (where n is an integer greater than one, such as a number between two and fifteen). Thus, it is possible to have several images (series of images), both the first flat reference surface and the second inclined reference surface, which makes it possible to process by means of computational algorithms not one image of the first flat reference surface and the second inclined reference surface, but a series of such images. , and thus reduce the measurement error.

Specifically, according to one possible embodiment, such imaging(s) of the first flat reference surface and the second inclined reference surface is performed by an optical system that is used without the need for adjustment, as will be explained below. In this case, there is no special setup that needs to be done in the optical system, which provides a significant time saving when measuring the relative position of a three-dimensional target. This technical solution provides a noticeable advantage compared to existing technical solutions, consisting in the fact that neither several measuring operations (stages) nor changing the settings, in particular, the focal length of the optical system that looks at the target, is required.

Also, when this target is used to measure the position of the tool holder relative to the workpiece holder, it becomes possible to ensure independence from tool wear and changes in the temperature of the tool and/or the working space of the machine in which the workpiece (part) to be processed is placed by mounting the target on the tool holder. .

The present invention also relates to a three-coordinate optical measuring device for measuring the location of a first object relative to a second object, containing the three-coordinate target discussed above, intended for installation on the first object, and an optical system containing the first imaging system and the second imaging system, and intended for installation on the second object. object, and the difference between the focal length of the second imaging system and the focal length of the first imaging system lies in the interval between the minimum distance and the maximum distance separating the base surface from the inclined surface.

Thus, the optical system can simultaneously determine its position relative to, on the one hand, the reference surface (or the first reference surface) by means of the image formed by the first imaging system, and, on the other hand, relative to at least one zone of the inclined surface (or the second reference surface) , which is determined by the image generated by the second imaging system, whose position on the target relative to the reference surface is known.

Such an optical system can be placed on one of the two objects under consideration (the second object), and makes it possible, by means of two imaging systems, to shoot two sharp images at two closely spaced locations on the other of the two objects (the first object), while these two places on the first object are located at slightly different distances from the second object. Such an optical system makes it possible, as will be discussed in more detail below, by means of two images to register (in three coordinates) the position of the first object relative to the second object, which carries the optical system.

In accordance with one possible embodiment, the optical system is arranged such that the optical path from the object (the first object) passes through at least part of one of the survey systems - the first or the second survey system - before reaching the other of said survey systems. Thus, it is possible to have a portion of the optical path as input/output of the optical system that is common to or very close to the first and second imaging systems. In this way, it is possible not only to combine the first and second imaging systems in the same optical system, but also to be able to capture images of two closely spaced locations on the first object that are separated by a few tenths of a millimeter, even a few millimeters, or at a distance of less than one millimeter.

The present invention also relates to a system for three-dimensional optical measurement of the location of a first object relative to a second object, comprising:

is an aggregate containing the first object and the second object, and

- the optical measuring device discussed above.

According to the first option, the optical measuring device is constructed in such a way that:

- the first imaging system is designed so that its rear focal plane can coincide with the base surface of the first structure, and

- the second imaging system is designed so that its rear focal plane can intersect the inclined surface of the three-coordinate target.

In accordance with the second option, compatible with the first option, or taken separately, the optical measuring device is constructed so that:

- the focal length of the first imaging system allows you to place the focus of the image on the first structure,

- the focal length of the second imaging system allows you to place the focus of the image on the second structure

Said unit is, for example, a piece of equipment, a machine tool, a module, in particular, a scientific or technical module containing a first object and a second object that can be moved relative to each other, and for which it is necessary to perform the operation of registering the relative position in three-dimensional space. For example, said assembly is a metal-cutting machine or machine module, in which the first object is a tool holder or one of the tool holders, and the second module is a workpiece holder that carries the workpiece to be processed (bar, blank, etc.). According to another example, the assembly is a block for mounting electronic components on a printed circuit board, while the first object is the holder of the printed circuit board, and the second object is a clamp or other tool for installing the electronic component. According to yet another example, the assembly is a cell culture module for seeding a series of wells on microplates, wherein the first object is a microplate holder and the second object is a device holder for injecting cells to be cultured.

The present invention also relates to a method for three-coordinate optical measurement in accordance with three orthogonal directions X, Y and Z of the position of the first object with respect to the second object, which are in line and spaced from each other in the main Z direction, comprising the steps of:

- - provide for a three-coordinate target, which forms the base for counting positions and contains on the working face:

• a first structure forming a flat base surface divided into at least:

- the first area, the surface of which has diffuse reflection properties, and

- the second section, the surface of which has the properties of mirror reflection, and the second section is divided into a number of local zones located in the first section, and

• a second structure containing a surface that is inclined relative to the specified flat base surface,

- provide an optical system containing the first imaging system and the second imaging system,

- the specified three-coordinate target is placed on the first object,

- the specified optical system is placed on the second object so that, on the one hand, the focal length of the first imaging system allows you to place the image focus of the first imaging system on the first target structure, and, on the other hand, the focal length of the second imaging system allows you to place the image focus of the second imaging system on the second target structure,

- at least one exposure is made simultaneously by means of the first imaging system belonging to the optical system and by means of the second imaging system belonging to the optical system, and thus for each exposure performed by means of the optical system, on the one hand, the first imaging system forms the first image of the target , which makes it possible to determine the position of the second section relative to the first section (in particular, the position of local zones) on the base surface, which gives, firstly, the first part of the information about the position of the target relative to the first imaging system in the X direction, and, secondly, the second part of the information about the position of the target relative to the first imaging system in the Y direction, and, on the other hand, the second imaging system forms a second image of the target, containing a sharply imaged area corresponding to the location of the inclined surface of the second structure, which gives the third part of the information about the distance between the target and the second camera system in the Z direction. In accordance with one possible embodiment, said optical system is configured so that the difference between the focal length of the second camera system and the focal length of the first camera system lies in the interval between the minimum distance and the maximum distance separating the base surface from the inclined surface . In accordance with another possible embodiment, said optical system is configured so that the optical path of the first imaging system and the optical path of the second imaging system have a common area, including the rear focal plane of the first imaging system and the rear focal plane of the second imaging system. According to yet another exemplary embodiment, taken alone or in combination with one or both of the preceding embodiments, the depth of field (DOF1) of the first imaging system is at least ten times greater than the depth of field (DOF1) of the second imaging system. systems.

By means of this method it is possible to obtain spatial geometric information associated with the (first) reference surface and with the inclined surface (or second reference surface) of a three-coordinate target, which makes it possible, on the basis of said information, to infer the position in the three spatial directions X, Y and Z of the first object relative to the second object. First, a three-coordinate binding of the target position with respect to the first object will be performed, and a three-coordinate binding of the position of the optical system with respect to the second object.

It is important to note that, according to one embodiment, exposure or imaging by each camera system of the optical system is performed without focusing the respective camera system. Indeed, it is the position (in three coordinates) of the imaging system relative to the object that the imaging system is looking at (and, consequently, both the position of the first imaging system relative to the base surface and the position of the second imaging surface relative to the inclined surface of the target) and the optical properties, but, in particular, the very different depth of field of the imaging systems belonging to the optical system makes it possible to simultaneously form two images: respectively, the base surface and the inclined surface. The analysis of these two images (even two series of images) makes it possible to obtain information about the position of the target relative to the optical system along the X coordinate (this X direction corresponds, for example, to height), along the Y coordinate (this Y direction corresponds, for example, to the horizontal lateral displacement) and along the Z coordinate (this Z direction corresponds, for example, to the main horizontal distance), and hence information on three coordinates about the relative position of the first object, which carries the three-coordinate target, and the second object, which carries the optical system.

According to one embodiment, after placing a three-coordinate target on the first object and placing the optical system on the second object, an additional step of determining the spatial position of the target in X, Y and Z coordinates relative to the first object by means of the optical system is performed.

According to one possible embodiment, the second area of the flat base surface is divided into a number of local areas located on the first area, while the first image formed by the first imaging system makes it possible to determine the position of the local areas of the second area on the base surface, which provides information about the relative location said local areas and the first imaging system, allowing relative measurement in the Y direction and X direction.

According to one embodiment, the method according to the invention is a method for measuring in three-coordinate machine space the position of a tool holder relative to a workpiece holder, in which the first object is said tool holder and the second object is said workpiece holder, and before said step of simultaneous shooting by means of an optical system, an additional step in which:

- the tool holder and the workpiece holder are placed on the same line in the main direction Z so that the working face of the three-coordinate target is located in the optical path of the optical system.

According to another possible embodiment, the optical device also includes a third imaging system located on the tool holder and configured to register the orientation of the target working face and/or the angular position of the tool holder.

Brief description of the drawings

Examples of the implementation of the invention are indicated in its description, illustrated by the accompanying drawings, in which:

fig. 1 shows a three-dimensional measuring device which comprises a three-dimensional target according to the invention and an optical system;

fig. 2A illustrates the use of the triaxial measuring device of FIG. 1 in a machine tool to measure in space the position of a tool holder relative to a workpiece holder (which is also referred to as a material spindle);

fig. 2B shows a part of FIG. 2A corresponding to a tool holder with a three-coordinate target as viewed in the direction IIB of FIG. 2A, i.e. in the Z direction as the optical system "sees" it when the target is directed towards the optical system;

fig. 3A, 3B and 3C are three views illustrating the construction of a three-coordinate target according to the invention, respectively, frontal view, axonometric view and sectional view; and fig. 3D and 3E show a perspective view of a second target structure corresponding to FIG. 3A, 3B and 3C according to the embodiment;

fig. 4A and 4B illustrate the processing of an image formed by the second pickup system of the optical system;

fig. 5 shows a perspective view and exploded view of a tool holder equipped with a three-dimensional target according to the invention;

fig. 6 illustrates the installation of a three-dimensional optical measuring device on a tool holder.

Implementation of the invention

In FIG. 1 shows an optical device 10 comprising an optical system 100 and a three-dimensional (volumetric) target 200 that can cooperate with each other to perform a three-dimensional position measurement of the target 200 and the optical system 100. In fact, in this measurement position, the target 200 is oriented in the direction of the optical system 100 parallel to the main axis, which forms the main horizontal direction Z. To this end, at the output of the optical system 100, the path O of the optical beam is orthogonal to the working face 202 of the target 200.

The target 200 will be further described with reference to FIG. 1, 3A, 3B and 3C. The target 200 is in the form of a cylindrical tablet with a circular cross section (the target may have a square or other cross section), in which one side forms a working face 202 for making measurements. Therefore, in order to carry out measurements, this working face 202 is rotated in the direction of the optical system 100, in particular, in the direction of the input side 102 of the optical system 100, while the Z axis corresponding to the main direction (horizontal direction in the figures) separates the working face 202 from the input side 102 optical system 100.

The facet surface 202 of the target 200 is divided between the first structure 210 and the second structure 220. The first structure 210 includes a flat base surface 212 that is smooth and is divided between a first region 214 that is diffusely reflective and a second region 216 that is specularly reflective. In one embodiment, the first region 214 is coated with a diffusely reflective layer, such as barium sulfate BaSO4, and the second region 216 is formed with a specularly reflective layer, such as a chromium layer. According to the depicted embodiment, the second section 216 is made in the form of several local zones 217 in the form of circles forming "islands" located within the first section 214, which is continuous. These local zones 217 may be of a different form, for example, they may have the form of segments or "islands" of a different shape than circular. These local zones 217 together form a geometric figure - one of the following list: quadrilateral, parallelogram, rectangle, square, rhombus, regular polygon and circle. This geometric figure can be a figure with central symmetry. In FIG. 3A and 3B, twenty-four circular local zones 217 are arranged in a square pattern. The purpose of the first structure 210 is to accurately recognize the center C3 using standard video tools. In the case of a figure of the "square" type, two diagonals C1 and C2 of the specified square intersect in its center. It should be noted that when measuring the position as shown in FIG. 1-3 and 5, the reference surface 212 is arranged parallel to the X and Y directions, respectively forming a vertical direction (axis) and a transverse horizontal direction (axis) in the case of such an arrangement as shown.

The second structure 220 includes a surface 222 that is inclined relative to the base surface 212; while this inclined surface 222 is substantially flat, and the median plane of this inclined surface forms with respect to the base surface 212 an acute angle a, lying in the range of 10° - 80°, for example, an angle of 20° - 30°, and preferably an angle of the order of 25° ( see Fig. 3C).

According to one embodiment, this sloped surface 222 is not smooth, but contains terrain elements 224 that create surface irregularities that are either random or have a predetermined geometry, for example, together form a lattice or grid of lines, thus constituting a structured lattice (not shown) or a structured grid of lines (see FIG. 3D).

Such relief elements 224 may be in the form of protrusions or recesses, i. e. may be offset back relative to the median plane of the sloped surface 222, particularly in the form of a slight roughness or any other surface irregularity. Such features 224 may be present throughout the sloped surface 222. Such features may be evenly distributed throughout the sloped surface 222. surface or rough surface that makes it possible to obtain sufficient scattering of light reflected from the sloped surface 222. The sloped surface 222 of the second structure 220, for example, is covered with one of the following elements: an etched mesh or a structured grating, in which the distance (pitch) between the elements lies in the range of 5-100 µm, in particular in the range of 5-50 µm, including 8-15 µm, for example, is of the order of 10 µm.

For example, this sloped surface 222 is made of unpolished silicon, or ceramic, or unpolished metal or glass, or any other material that allows structure to be obtained, with relief elements 224 obtained by photolithography, by machining with chip removal, by direct forming a picture (letter), or in any other way that allows you to form a structure. Said relief elements 224 form, for example, depressions and/or protrusions, which are respectively spaced back from the median plane and/or moved forward beyond the median plane by a few microns or a few tens of microns, in particular by 0.5-50 µm. .

According to another embodiment, as shown in FIG. 3E, this sloped surface 222 is smooth and contains a grid of lines of chromium or other material to mirror said lines of chromium which form mirror elements 225. Said line-shaped mirror elements 225 are arranged parallel to each other. In the measuring position, said mirror elements 225 in the form of lines or strips are arranged parallel to the Y, Z plane, so that along the inclined surface in the Z direction, said lines meet one after the other (the same is observed when moving in the X direction). The substrate forming the plate of the second structure 220 may be made of various materials, including glass or silicon, with a diffusely reflective layer on the sloped surface 222 made, for example, of barium sulfate BaSO4, which alternates with the mirror elements 225, or which covers the entire inclined surface, and the mirror elements 225 are located on top of this diffusely reflective layer. According to an exemplary embodiment, these mirror elements 225 in the form of lines form a grid with a pitch of 25 µm. In this case, these lines (in particular, from chromium) have a width of 12.5 μm equal to the width of the gaps between the lines or areas of diffuse reflection, which also have the form of lines or stripes with a width of 12.5 μm. In accordance with another embodiment, a pitch of 10 µm or more is used, in general a pitch in the range of 5-50 µm. It should be noted that the mirror elements 225 that alternate with the rest of the diffuse reflective surface may have a shape other than solid lines or segments forming stripes; in particular, it can be broken lines, figures such as dotted borders, circles, triangles, or any other geometric shapes.

According to an embodiment that is not shown in the drawings, the sloped surface 222 of the second structure 220 bears a region that bulges forward the relief elements 224 in the form of small ridges or wedges, which are distributed in mutually parallel rows, while the relief elements 224 are mutually offset from one row to another to get a stepped figure. According to another embodiment, which is not shown in the drawings, the sloped surface 222 of the second structure 220 bears raised elements 224 in the form of segments that are parallel to each other and equidistant and correspond to two series intersecting at an angle of 90° to each other. Such a set of relief elements 224 forms a lattice pattern. It should be noted that this grating can be formed by two series of mutually parallel segments that intersect each other at an angle other than 90°. In FIG. 3A, 3B, 3C, and 3D, the sloped surface 222 of the second structure 220 bears landforms 224 which are recessed in a series of segments that are parallel to each other and spaced at equal distances from each other in the X direction: these landforms 224 form in this case grooves. Therefore, the direction X is orthogonal to the direction of the segments that form the elements 224 relief.

Therefore, in the embodiment shown in FIG. 3E, the inclined surface 222 of the second structure 220 is covered with a grid of specular lines 225, namely, mutually parallel solid strips, the surface of which has the property of specular reflection.

Thus, in some of the cases mentioned above, and in particular those illustrated in FIG. 3D and 3E, the sloped surface 222 of the second structure 220 has a grooved structure.

In accordance with the embodiments presented for the target 200, the tablet that defines the target 200 contains on its working face 202 the first structure 210, which occupies the majority of the area of the working face 202, and within the first structure 210, the zone occupied by the second structure 220. In this situation, the first structure 210 surrounds the second structure 220. More precisely, the local zones 217 of the second section 216 of the first structure 210 form a square that surrounds the second structure 220. In accordance with one possible condition, and in the case of the embodiments of the target 200 presented in the drawings, the first the structure 210 and the second structure 220 are located on the working face 202 concentric to each other. Moreover, as in the illustrated embodiments, the first structure 210 defines a window boundary 218 for the body 219 housing the second structure 220, which is, for example, placed on a plate that has an inclined surface 222. When the plate is placed in the body 219 of the first structure 210, its sloped surface 222 is turned outward from the housing 219, towards the window 218. In this particular case, the second structure 220 is located in the housing 219 so that the sloped surface 222 is set back relative to the base surface of the first structure 210: this means that the sloped surface 222, and hence the second structure 220, are located behind, behind the plane bounded by the base surface 212 (relative to the main direction Z, see Fig. 3B) in the housing 219, and are offset back, for example, by 0.05-2 mm or approximately 0.15 mm. According to another possible option, which is not shown in the drawings, the second structure 220 is placed in front of the plane bounded by the base surface 212. According to another possible option, which is also not shown in the drawings, the second structure 220 is located on each side of the plane bounded by the base surface 212, namely, part of the sloped surface 222 is located behind, and the other part of the sloped surface 222 is located in front of the base surface 212.

In order to protect the first structure 210 and the second structure 220 from the environment (dust, oil, shock, etc.), as can be seen in FIG. 3C, the target 200 includes a protective plate 230 of a transparent material, in particular glass, covering the first structure 210 and the second structure 220 from the side of the working face 202. In accordance with one possible embodiment, as shown in FIG. 3C, target 200 contains the following items as a package. The bottom wall 231, on top of which the top plate 232 is installed, in the center of which a cutout is made that defines the boundaries of the body 219, the boundary of which on the side of the working face 202 is defined by a window 218. From above, the top plate 232 is covered with a protective plate 230 that closes the body 219. All of these elements together surrounded by a cylindrical wall 234 which holds the entire target 200. The second structure 220 is, for example, enclosed in a housing 219 a silicon wafer with an inclined surface 222 (which bears relief elements 224 or mirror elements 225) rotated in the direction of the working face 202 The surface of the top plate 232, facing the working face 202, contains a reflective layer 233 in the form of two zones, as discussed above with respect to the first section 214 (diffuse reflection surface) and the second section 216 (specular reflection surface), in particular in form of local elements 217).

In addition, the target 200 can be equipped with radio frequency identification RFID (RFID, eng. Radio Frequency Identification) (not shown) to enable the storage and reading of a unique identifier and data relating to the target 200, and related to the first object on which the target 200, in particular the tool holder 310 (see Figs. 5 and 6), is supposed to be installed: for example, reference information on the tool holder 310 and other information related to the use of this tool holder (for example, its serial number, type , its setting relative to the center of the material of the workpiece holder, the number of times the tool holder is used, etc.).

Further, according to FIG. 1, an optical system 100 will be considered associated with the target 200 just described, which together form an optical measurement device 10 which allows measurement of the relative position of two objects in three spatial coordinates. In particular, the orthogonal space is considered in the Cartesian coordinate system X, Y and Z, which is indicated in the drawings. This optical system 100 is designed to simultaneously record, in the same sequence of exposures (shootings), both the image of the first structure 210 of the target 200 and the image of the second structure 220 of the target 200. According to the present description, this simultaneous shooting of two images is carried out without adjustment, which gives a high speed of such shooting. Other properties, in particular related to the special design of the target 200 discussed above, also allow maximum accuracy to be achieved. The three-coordinate optical measuring device 10 according to the present invention is capable of reproducibly measuring the relative positions of objects with an error of 1 μm or less in 1/2 second or faster.

The optical system 100 includes a first imaging system 110 and a second imaging system 120. According to one embodiment, said optical system 100 is configured such that the difference between the focal length of the second imaging system 120 and the focal length of the first imaging system 110 lies between a minimum distance and a maximum distance. the distance separating the base surface 212 from the inclined surface 222. According to another embodiment, the depth of field (DOF1) of the first imaging system 110 is much larger, in particular at least ten times the depth of field (DOF2) of the second imaging system 120. For example, the depth of field DOF1 of the first camera system 110 exceeds the depth of field DOF2 of the second camera system 120 by 10-10000 times, or 100-5000 times. Among the different possible characteristics: DOF1 of the first imaging system is greater than or equal to 0.8 mm, or in the range of 0.5-5 mm, or in the range of 0.8-3 mm, or in the range of 1-2 mm. Also among other possible characteristics: DOF2 of the second imaging system is less than or equal to 0.1 mm, or is in the range of 5-50 µm, or in the range of 8-30 µm, or in the range of 10-20 µm.

This allows the first imaging system 110 to focus naturally and without other adjustments on the entire base surface 212 of the first structure 210 over a range of distances between the target 200 and the first imaging system 110, which may vary within a few millimeters.

In parallel, the second imaging system 120 can naturally and without other adjustments focus on a portion of the inclined surface 222 of the second structure 220, which is located at a distance from the second imaging system 120, which corresponds to the focal length of the second imaging system 120. According to one possible option, the increase in the first imaging system system 110 is less than or equal to the magnification of the second imaging system 120.

Each imaging system according to the present invention (the first imaging system 110 and the second imaging system 120) corresponds to an optical system, in particular, a centered optical system containing a set of optical elements and an imaging system. Such an imaging system enables the acquisition of photographs and/or videos, and is, for example, a camera or a photographic apparatus, in particular a digital camera. According to one exemplary embodiment, the first imaging system 112 of the first imaging system 110 and the second imaging system 122 of the second imaging system 120 are synchronized to simultaneously capture the first image by the first imaging system 110 and the second image by the second imaging system 120.

In order for the first imaging system 110 and the second imaging system 120 to simultaneously view the target 200, these systems have a common optical path that is directed forward and originates from the object monitored by the optical system 100; in this case, the target 200 (see Fig. 1 and 2) is installed on the first object, and the optical system 100 is installed on the second object. To this end, in the measurement position, the first imaging system 110 is rotated in the direction of the working face 202 of the target 200, and forms an imaging system centered with the target 200, while the second imaging system 120 corresponds to the optical path 126, which meets the optical path 116 of the first imaging system. 110 (which is centered with the target 200) and forms a survey system that is offset relative to the target 200 relative to the optical axis O of the optical system 100, and relative to the common portion of the optical paths 116 and 126, which is centered with the target. In other words, the optical path of the imaging system, centered on the target 200, is oriented essentially at right angles to the reference plane 212. The optical axis O is aligned with the middle beam of the common section of the first optical path 116 and the second optical path 126. In this common section, the segments of the first optical path 116 and the second optical path 126 are mutually parallel, but not necessarily aligned with each other.

In particular, as shown in FIG. 1 and 2, the first imaging system 110 is rotated in the direction of the working face 202 of the target 200, in other words, is oriented at right angles to the working face 202 of the target 200. This means that the optical axis O and the common section of the optical paths 116 and 126 are centered with the target 200 and are located at right angles to the working face 202 (and therefore to the base surface 212) of the target 200. With this configuration, as can be seen in FIG. 1 and 2, the optical axis O and the common portion of the optical paths 116 and 126 are parallel to the main Z direction, and orthogonal to the X and Y transverse directions and the X, Y plane.

In the common area of the optical paths 116 and 126, the optical beams at least partially merge with each other, or are simply parallel to each other. The second imaging system 120, which is offset, has a portion of the optical path 126 (inside the second imaging system 120) which is preferably parallel to the optical axis O. filming system 110; while its centering is carried out by a specialized optical module 128 containing a catoptric (reflective) optical system, such as a mirror 129. first filming system 110).

More generally, one of the imaging systems - the first system 110 or the second system 120 - is turned in the direction of the working face 202 of the target 200, and forms a survey system centered with the target 200, and the other of these survey systems has an optical path 126, which meets with the optical path 116 of the imaging system centered on the target 200 and forms an offset imaging system. This means that said other imaging system has an optical axis that passes through the inclined surface 222, i.e. through the second structure 220 of the target 200. Also, the first shooting system 110 and the second shooting system 120 are arranged parallel to each other. In addition, the optical system also includes an optical module 128 (for example, with a catoptric optical system such as a mirror) located between the first imaging system 110 and the second imaging system 120, and configured to deflect a portion of the light rays passing through at least part of one from the survey systems (first or second) towards another of the survey systems (first or second). Conversely, the optical system 100 is designed so that the optical path from the observed object (target 200 in Figs. 1 and 2) due to the optical system 100 passes through at least part of one of the imaging systems - the first imaging system 110 or the second imaging system 120 - (first survey system 110 in FIGS. 1 and 2) before reaching the other of said survey systems (second survey system 120 in FIGS. 1 and 2).

According to one embodiment, the focal length of the second imaging system 120 is greater than the focal length of the first imaging system 110. For example, the focal length difference between the second imaging system 120 and the first imaging system 110 is in the range of 0.5 mm to 5 mm.

According to one embodiment, the magnification of the first imaging system 110 is less than or equal to that of the second imaging system 120. For example, the magnification of the first imaging system is 0.8-1 that of the second imaging system 120. For example, the magnification of the first imaging system is in the range of 0.3 -0.8 or 0.4-0.6 magnification of the second imaging system, and preferably about 0.5 magnification of the second imaging system 120.

In the embodiment depicted in FIG. 1 and 2, the optical system 100 also includes an illuminator 140 oriented in the direction of the three-coordinate target 200. The illuminator 140 is positioned to provide lateral illumination of the target 200. To this end, this illuminator 140 is positioned off-center and tilted relative to the optical path 116+ 126 of the optical system 100. In particular, the light rays from the illuminator 140 form an angle with the base surface 212 of the target, so that their specular reflection from the reflective surfaces of the target, and in particular the local zones 217, forms reflected light rays that do not enter the optical system. 100. Similarly, when the sloped surface 222 includes mirror elements 225, the reflection of light rays coming from the illuminator 140 from said mirror elements 225 does not enter the optical system 100.

According to one embodiment, the first used filming system 110 and the second used filming system are telecentric. As a reminder, telecentricity is the characteristic of an optical system whereby all of the main beams (the center beam of each beam) that pass through the system are nearly collimated and parallel to the optical axis. In the case of telecentric optics, the concept of the depth of the sharply depicted space is replaced by the concept of the working distance. According to another embodiment, the first usable survey system 110 and the second usable survey system 120 are not telecentric, or both are not telecentric. In case both systems are telecentric, they can also be used to measure the geometry of the tool located on the tool holder 310.

Further, according to FIG. 2A-6, a method for three-dimensional optical measurement of distances between a target 200 and an optical system 100 will be discussed in the case of a metal cutting machine, in which the machine module 300 includes an optical device 10. The reference directions X, Y and Z are the reference directions of the machine module, in particular the coordinate system machine module that gives the vertical X direction (or the first transverse axis), the main horizontal direction Z (or the main axis) and the transverse horizontal direction Y (or the second transverse axis). The target 200 is placed on the tool holder 310, which serves as the first object (see Fig. 5): the tool holder 310 extends in the main horizontal direction, which corresponds to the X axis, with the possibility of rotation around the X axis. To this end, part of the holder 310 a tool, such as a clip, has recesses on its peripheral surface, typically for receiving a grip/release tool, and into which a target 200, possibly associated with an RFID chip, as previously discussed, can be placed. In addition, the optical system 100 is mounted on a workpiece (workpiece) holder 320, which serves as a second object (see FIG. 6) and receives a workpiece 322 to be machined. The work holder 320 extends along its main horizontal direction corresponding to the Z axis and is rotatable about the Z axis. processing, the parts were in close proximity to each other, in the position of measuring the relative position. The location of the target 200 on the tool holder 310 and the location of the optical system 100 on the workpiece holder 320 allows, in a given position for measuring the relative position, the target 200, or rather the base surface 202, to be located on the continuation of the optical axis O of the optical system 100 (it should be noted that the specified optical axis O parallel to the Z direction). Thus, the base surface 202 of the target 200 is turned towards the input side 102 of the optical system 100.

As shown in FIG. 6, the optical device 100 also includes a third imaging system 130 located on the tool holder 310 and configured to register the orientation of the working face 202 of the target 202 or the angular position of the rotating part of the tool holder 310, in particular with respect to the X axis. 200 is performed before the simultaneous shooting step with the optical system 100, according to which:

- the tool holder 310 and the part holder 320 are positioned so that the working face 202 of the spatial target 200 is on the optical axis O of the optical system 100. In particular, the third imaging system 130 can be used to record the angular position of the target 200 relative to the rotating part of the tool holder 310, and therefore relative to the X axis, which makes it possible to change (if necessary) the angular position of the rotating part of the tool holder 310 (see arrow R in Fig. 6), and thus the position of the target 200 so that the working face 202 is rotated in the direction of the optical system 100. A relationship measurement position is obtained when the target 200 is oriented in the direction of the optical system 100, as discussed above with respect to FIGS. 1 and 2A: in this case, the Z direction passes between the target 200 and the optical system 100.

When first using the optical device 10 (namely, the optical system 100 and its associated target 200), respectively mounted on the workpiece holder 320 (or more generally on the second object), and on the tool holder 310 (or more generally - on the first object), a preliminary additional step of spatially referencing the position of the target 200 relative to the tool holder 310 (more generally, the first object) must be performed, which links the target 200 with the three directions X, Y and Z. It should be noted that the parameters are obviously of the optical system 100, namely the first imaging system 110 and the second imaging system 120 are known, including their focal lengths. At this stage, it can be noted that when the working space of the machine tool module 300 is limited and maintained at a constant temperature, its thermal stability determines the stability of the dimensions of the optical device 10 and hence its parameters.

It is worth recalling that the three-dimensional measurement of the relative position of the target 200 and the optical system 100 is used in the case of a metal cutting machine in order to ultimately know in the form of X, Y and Z coordinates the spatial relative position of the tool holder 310 (or more generally the first object) and the holder 320 details (or more generally - the second object).

In this description, the three directions X, Y, and Z are, for example, the axes of the machine tool module 300 of the machine. Thus, the Z direction can be defined as the main axis, namely the main horizontal direction separating the first object (tool holder 310) from the second object (workpiece holder 320). The X direction may be defined as the vertical direction (or more generally the first transverse axis) and the Y direction may be defined as the transverse horizontal direction (or more generally the second transverse axis. In one embodiment, the holder 310 tool rotates around an axis parallel to the X direction.

At this stage of the spatial referencing of the position of the target 200 in three coordinates X, Y and Z (calibration of the optical device 10), for example, in the scheme corresponding to Fig. 2A and 2B, the acquisition by means of the optical system 100 is activated, which leads, on the one hand, to the formation by the first imaging system 112 belonging to the first imaging system 110 of the first image of the entire working facet 202 of the target 200 with the entire base surface 212 that is imaged. sharply, and on the other hand to the formation by the second imaging system 122 belonging to the second imaging system 120 of a second image of the entire inclined surface 222 of the target 200 with a single sharply imaged zone in the form of a horizontal strip. Said first image contains an image of local areas 217, which in this case define a square (see FIG. 3A), so that the processing of the first image gives the diagonals C1 and C2 of the square, and makes it possible to determine the center C3 of the square. Thus, since the position of the optical axis O in the first image is known, determining the position of the center C3 of the square makes it possible to know in X coordinates and Y coordinates the position of the target 200 relative to the optical axis O, but also, on the one hand, relative to the anchor point 314 in the X direction on tool holder 310, and, on the other hand, relative to the anchor point 316 in the Y direction on the tool holder 310. In fact, as can be seen in FIG. 2A and 2B, the surface of the tool holder 310 that is orthogonal to the X axis is used as the reference in the X direction, for example, formed by a shoulder on the body of the tool holder 310, which appears as a line in the first image, and whose surface forms the anchor point 314 in the X direction. In addition, as can be seen in FIG. 2A and 2B, the dimension of the tool holder 310 in the vicinity of the target 200 that is orthogonal to the X axis and which in the depicted case is the width (parallel to the Y direction) of the tool holder 310 in the vicinity of the target 200 is used as the reference in the Y direction, for example, the diameter when this part of the tool holder 310 is cylindrical with a circular section; this size (gauge) forms the anchor point 316 in the Y direction.

In parallel, a second image is processed, an example of which is seen in FIG. 4A. By analyzing the local contrast of this second image (see Fig. 4B, which shows contrast curves depending on the position in X coordinates), the position X0 of the sharpened zone of the second image in the vertical X direction is determined. This analysis is performed by an algorithm that makes it possible to determine the sharpest image pixels. Since the inclination of the slope 222 is known, a correspondence curve between X and Z of a given slope 222 specific to the target 200 is obtained. Due to this correspondence curve, knowing the position X0 (see FIGS. 4A and 4B) makes it possible to obtain the position Z0 of the slope 222 from this. on the optical axis O, and hence the Z position of the target 200 relative to the optical system 100. In addition, the Z position of the optical system 100 relative to the workpiece holder 320 is known from the data of a measuring ruler (not shown), which is located along the X axis on workpiece holder 320, and which supports the optical system 100. Similarly, the Z position of the target 200 relative to the anchor point 314 of the tool holder 310 is known.

By repeatedly performing this operation, each time changing the distance along the Z coordinate of the workpiece holder 320 relative to the tool holder 310 (for example, by retracting or feeding the tool holder 310), it is thus possible to reconstruct the three-dimensional image of the inclined plane 222 of the target 200, and obtain a reference base, which in Cartesian coordinates displays the inclined surface 222 of the target 200 relative to the holder 310 of the tool. Ultimately, it's all about the working face 202 of the target 200 (base surface 212 and ramp 222) that is spatially referenced in the three X, Y, and Z directions relative to the tool holder 310.

Then, whenever it is necessary in the operations of using the machine module 300 equipped with the target 200 and the optical system 100, the actual measurement can be performed without disassembling the system between measurement points in order to maintain the spatial reference measurement accuracy that was explained above. For this purpose, for example, the circuit of FIG. 2A. If necessary, rotate the tool holder 310 about its axis of rotation, which is parallel to the X axis (see arrow R in Fig. 6) to center the target 200 with the optical system 100. on the one hand, to the formation by the first imaging system 112 of the first imaging system 110 of the first image of the entire working face 202 of the target 200 with the entire base surface 212, which is in the field of sharpness, and, on the other hand, to the formation by the second imaging system 122 of the second shooting system 120 of the second image of the entire inclined surface 222 of the target 200 with only one sharply depicted zone in the form of a horizontal strip corresponding to the focal length of the second shooting system 120. Analysis of the first image makes it possible, as mentioned above, to determine the center C3 of the square formed by local elements 217, and thus, in X coordinates and in Y coordinates, determine the position of the target 200 with respect to the optical axis O as well as with respect to the tool holder 310. Analysis of the second image, and in particular the position of the sharply imaged area of the second image (as in Fig. 2A) in the X direction, makes it possible to determine this position in Z coordinates, and hence the distance of the target 200 relative to the optical system 100. In fact, with regard to the second image Because the Z position of each image pixel of the ramp 222 relative to the anchor points 314 and 316 of the tool holder 310 is known, it is possible to measure the Z position of the target 200 and hence the tool holder 310 very quickly.

From the foregoing, it should be understood that in this way, solely by analyzing the two images formed by the optical system 100, without wasting time for adjusting or adjusting the optical system 100, the position of the target 200 relative to the optical system 100 in the X, Y and Z coordinates can be very quickly measured, starting from the position of the tool holder 310 relative to the workpiece holder 320. This is possible because the position of the optical system 100 relative to the workpiece holder 320 is known in X, Y, and Z coordinates.

The present description also relates to an optical system for three-dimensional measurement of the relative position of the first object and the second object, on which the specified optical system is supposed to be installed, containing the first imaging system and the second imaging system, in which:

- the depth of field of the first imaging system is at least 10 times greater than the depth of field of the second imaging system, and

- the optical system is designed so that the optical path of the first imaging system and the optical path of the second imaging system have a common area containing the rear focal plane of the first imaging system and the rear focal plane of the second imaging system.

The present description also relates to a method for three-coordinate optical measurement in accordance with the three orthogonal directions X, Y and Z of the relative position of the first object and the second object, which are installed on the same line and spaced from each other in the main Z direction, in which:

- provide for a three-coordinate target, which forms the base for counting positions and contains on the working face:

• a first structure forming a flat base surface divided into at least:

- the first area, the surface of which has reflective properties in accordance with the first reflection parameters, and

- a second section, the surface of which has reflective properties in accordance with the second reflection parameters, which differ from the first reflection parameters, and

• a second structure containing a surface that is inclined relative to the specified flat base surface;

- provide an optical system containing the first imaging system and the second imaging system, in which:

- the depth of field of the first imaging system is at least 10 times greater than the depth of field of the second imaging system, and

- the optical system is made, on the one hand, so that the optical path of the first imaging system and the optical path of the second imaging system have a common area containing the rear focal plane of the first imaging system and the rear focal plane of the second imaging system, and, on the other hand, so that the difference between the focal lengths of the second imaging system and the first imaging system lies in the interval between the minimum distance and the maximum distance separating the base surface from the inclined surface,

- the specified three-coordinate target is placed on the first object so that, on the one hand, the focal length of the first imaging system allows you to place the focus of the image of the first imaging system on the first target structure, and, on the other hand, the focal length of the second imaging system allows you to place the focus of the image of the second shooting system systems on the second target structure,

- the specified optical system is placed on the second object,

- at least one exposure is made simultaneously by means of the first imaging system belonging to the optical system and by means of the second imaging system belonging to the optical system, and thus for each exposure performed by means of the optical system, on the one hand, the first imaging system forms the first image of the target , which makes it possible to determine on the base surface the position of the second section relative to the first section (or the position of local zones on the base surface), which gives, firstly, the first part of the information about the position of the target relative to the first imaging system in the X direction, and, secondly , the second part of information about the position of the target relative to the first imaging system in the Y direction, and, on the other hand, the second imaging system forms a second image of the target, containing a sharply imaged area corresponding to the location of the inclined surface of the second structure, which gives the third part of the information about the distance between the target and a second camera system in the Z direction.

As previously explained, the optical system 100 thereby synchronously forms the first image and the second image. In addition, the optical system 100 forms the first image and the second image without performing adjustment, which makes it possible to perform the exposure immediately and without loss of time.

The present description also relates to a metal-cutting machine containing the above-described optical target, while the metal-cutting machine contains the optical system described above. The present description also relates to a machine tool, comprising a machine module equipped with a tool holder and a workpiece (workpiece) holder, as well as an optical measuring device for three-dimensional measurement of the position of the tool holder relative to the workpiece holder; wherein the optical measuring device contains the specified optical system mounted on the part holder, and the target, which is mounted on the tool holder and contains a working face that forms the position reference base, and which can be located on the optical axis of the optical system. For example, the specified optical measuring device is made with the ability to determine the relative position of the holder of the workpiece and the tool holder in three coordinates by means of an optical system in one stage of shooting the target. Also, according to a possible embodiment, the target is positioned so that the rear focal plane of the optical system coincides with the working face of the target.

List of reference symbols used in the drawings

X Vertical direction (first transverse axis)

Y Lateral horizontal direction (second transverse axis)

Z Main horizontal direction separating the first object from the second object (major axis)

C1 Diagonal

C2 Diagonal

C3 Center

α Surface slope angle

R Arrow showing rotation of tool holder and target

10 Optical system

200 Three-coordinate target

202 Work face

210 First structure

212 Reference surface

214 First section (with diffuse reflection surface)

216 Second section (with mirror reflection surface)

217 Local zones

218 Window

219 Corps

220 Second structure

222 Incline

224 Relief elements

225 Mirror elements

230 Transparent protective plate

231 Bottom wall

232 Top plate

233 Reflective layer

234 Cylindrical wall

100 Optical system

About optical axis

102 Entrance end of the optical system

110 First filming system

DOF1 Depth of field of the first imaging system

F1 Rear focal plane of the first imaging system

112 First imaging system

120 Second camera system

F2 Rear focal plane of the second imaging system

DOF2 Depth of field of the second imaging system

122 Second imaging system

126 Optical path of the second imaging system

128 Optical module with catoptric optical system

130 Mirror

140 Illuminator (side illumination)

300 Machine module

310 Tool holder

312 Tool

314 X tool holder datum

316 Tool holder datum Y

320 Part holder or material spindle - second object

322 Workpiece (material)

Claims (46)

1. A three-coordinate target capable of serving as a position reference base, containing on the working face: • a first structure forming a flat base surface divided into at least: - the first area, the surface of which has reflective properties in accordance with the first reflection parameters, and - a second section, the surface of which has reflective properties in accordance with the second reflection parameters, which differ from the first reflection parameters, and the second section is divided into a number of local zones located in the first section, and • a second structure comprising an inclined surface that is substantially flat and inclined with respect to said flat base surface, wherein the inclined surface contains relief elements or mirror elements that are evenly distributed over the inclined surface. 2. A three-coordinate target according to claim 1, characterized in that these local zones together form a geometric figure, which is one of the following figures: quadrilateral, parallelogram, rectangle, square, rhombus, regular polygon and circle. 3. Three-coordinate target according to claim 1, characterized in that the local zones of the specified second section are formed by islands or segments, which are distributed in the first section. 4. A three-coordinate target according to claim 1, characterized in that the local zones are made of chromium. 5. A three-coordinate target according to claim 1, characterized in that the inclined surface contains relief elements that are evenly distributed. 6. A three-coordinate target according to claim 1, characterized in that the first structure and the second structure are located on the working face coaxially to each other. 7. Three-coordinate target according to claim 6, characterized in that the first structure surrounds the second structure. 8. A three-coordinate target according to claim 7, characterized in that the local zones of the second section of the first structure form a square that surrounds the second structure. 9. Three-coordinate target according to claim 1, characterized in that the first structure defines the boundaries of the window for the body containing the specified second structure. 10. A three-coordinate target according to claim 9, characterized in that the second structure is located in the specified housing together with an inclined surface, which is offset back relative to the base surface of the first structure. 11. A three-coordinate target according to claim 1, characterized in that the inclined surface of the second structure has a striped structure. 12. A three-coordinate target according to claim 11, characterized in that the inclined surface of the second structure is covered with one of the following elements: an etched grid, a structural grid, or a grid of mirror lines. 13. A three-coordinate target according to claim 1, characterized in that it also contains a plate of transparent material, in particular glass, covering the first structure and the second structure from the side of the working face. 14. A three-coordinate target according to claim 1, characterized in that one of the surface of the first section and the surface of the second section has diffuse reflection properties, and the other of the surface of the first section and the surface of the second section has specular reflection properties. 15. A three-coordinate target according to claim 1, characterized in that the surface of the first section has diffuse reflection properties, and the surface of the second section has specular reflection properties. 16. A three-coordinate target according to claim 1, characterized in that the inclined surface contains mirror elements that are distributed evenly over the inclined surface. 17. A three-coordinate optical measuring device for measuring the location of the first object relative to the second object, containing a three-coordinate target according to claim 1, intended for installation on the specified first object, and an optical system containing the first filming system and the second filming system and intended for installation on the specified second object, and the difference between the focal length of the second imaging system and the focal length of the first imaging system lies in the interval between the minimum distance and the maximum distance separating the base surface from the inclined surface. 18. A three-dimensional optical measuring device according to claim 17, characterized in that the depth of field of the first imaging system is at least ten times greater than the depth of field of the second imaging system. 19. A three-coordinate optical measuring device according to claim 17, characterized in that one of the first and second imaging systems is rotated in the direction of the working face of the target and forms a survey system centered with the target, and the other of the said first and second imaging systems contains an optical path, which meets with the optical path of the imaging system centered on the target and forms an offset imaging system. 20. A three-dimensional optical measuring device according to claim 17, characterized in that the first imaging system is turned in the direction of the working face of the target and forms a survey system centered with the target, and the second survey system contains an optical path that meets the optical path of the survey system centered with the target, and forms a shooting system, displaced relative to the target. 21. A three-dimensional optical measuring device according to claim 17, characterized in that it also contains an illuminator aimed at a three-dimensional target, and said illuminator is located so as to provide side illumination of the three-dimensional target. 22. A three-dimensional optical measuring device according to claim 17, characterized in that the first imaging system is telecentric and the second imaging system is telecentric. 23. A system for three-coordinate optical measurement of the location of the first object relative to the second object, comprising: - an aggregate containing the first object and the second object, - an optical measuring device according to claim 17, in which: - the first imaging system is designed so that its rear focal plane can coincide with the base surface of the first structure, and - the second imaging system is designed so that its rear focal plane can intersect the inclined surface of the three-coordinate target. 24. The system according to claim. 23, characterized in that the specified unit is a machine module; the first object is the tool holder and the second object is the material holder or part holder. 25. The method of three-coordinate optical measurement in accordance with the three orthogonal directions X, Y and Z of the position of the first object relative to the second object, which are on the same line and removed from each other in the main Z direction, including the steps in which: - provide for a three-coordinate target, which forms the base for counting positions and contains on the working face: • a first structure forming a flat base surface divided into at least: - the first area, the surface of which has reflective properties in accordance with the first reflection parameters, and - a second section, the surface of which has reflective properties in accordance with the second reflection parameters, which differ from the first reflection parameters, and the second section is divided into a number of local zones located in the first section, and • a second structure comprising an inclined surface which is substantially flat and inclined with respect to said flat reference surface, - provide an optical system containing the first imaging system and the second imaging system, while the optical system is designed so that the difference between the focal lengths of the second imaging system and the first imaging system lies in the interval between the minimum distance and the maximum distance separating the base surface from the inclined surface, - the specified three-coordinate target is placed on the first object, - the specified optical system is placed on the second object so that, on the one hand, the focal length of the first imaging system allows you to place the focus of the image of the first imaging system on the first target structure, and, on the other hand, the focal length of the second imaging system allows you to place the image focus of the second shooting system systems on the second target structure, - at least one exposure is made simultaneously by means of the first imaging system belonging to the optical system and by means of the second imaging system belonging to the optical system, and thus for each exposure performed by means of the optical system, on the one hand, the first imaging system forms the first image of the target , which makes it possible to determine the position of local zones on the base surface, which gives, firstly, the first part of the information about the position of the target relative to the first survey system in the X direction, and, secondly, the second part of the information about the position of the target relative to the first survey system in direction Y, and, on the other hand, the second imaging system forms a second image of the target, containing a sharply imaged area corresponding to the location of the inclined surface of the second structure, which gives the third part of the information about the distance between the target and the second imaging system in the Z direction. 26. The method according to claim 25, characterized in that after placing a three-coordinate target on the first object and placing the optical system on the second object, an additional step is performed to determine the spatial position of the target in X, Y and Z coordinates relative to the first object by means of the optical system. 27. The method according to claim 25, characterized in that for measuring, in the three-coordinate space of the machine module, the position of the tool holder relative to the workpiece holder, in which the first object is the specified tool holder, and the second object is the specified workpiece holder, before the specified stage of simultaneous shooting through the optical system, an additional step is performed, in which: - the tool holder and the workpiece holder are placed on the same line in the main direction Z so that the working face of the three-coordinate target is located in the optical path of the optical system. 28. The method according to claim 27, characterized in that the optical device also contains a third imaging system located on the tool holder and configured to register the orientation of the working face of the target and/or the angular position of the tool holder.

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