KR102543317B1 - Apparatus for measuring sub-aperture with surface extended radius of curvature range - Google Patents

Abstract

An apparatus for measuring the shape of a partial region having an extended radius of curvature is disclosed. A partial region shape measuring device for generating shape information on a partial region of an object according to the present invention includes: an incident unit for injecting light output from a light source into the partial region shape measuring device; an optical separation unit separating the incident light into reference light and measurement light; a reference light splitting unit configured to split the reference light incident into the optical splitting unit into a plurality of pieces; a plurality of reference mirrors having reflection surfaces formed according to predefined surface shape information and reflecting the plurality of reference lights incident from the reference light splitter toward the reference light splitter; a light receiving unit receiving interference light generated by the plurality of reference lights reflected from the plurality of reference mirrors and the reference light reflected from the surface of the partial region of the object under test; and a processing unit generating shape information about a partial region of the object to be inspected based on the interference light received by the light receiving unit. According to the present invention, an error tolerance range in which the radius of curvature of the reference mirror of the partial region shape measuring device and the surface of the object under test must match can be expanded.

Description

Apparatus for measuring the shape of a partial region having an extended radius of curvature

The present invention relates to a technology for measuring the shape of a large-area object under test, which measures shape information on partial regions of the object and stitches the shape information on the measured partial regions to measure overall shape information on the large-area object under test. It's about technology that can do it.

In the production process of optical parts, a sophisticated 3D shape measurement process is essential for quality evaluation, and various 3D shape measurement technologies are being used according to this demand. Among these, the shape measurement technology using an interferometer shows excellent performance in terms of measurement accuracy, but has limitations in measuring large-area objects due to the limited measurement area.

As a 3D shape measurement method proposed to overcome the limitations of this technology, overall shape information for a large-area object is obtained by measuring shape information on partial regions of an object under test and stitching the shape information on the measured partial regions. There has been proposed a technique (partial aperture stitching technique) capable of measuring . Referring to FIG. 1 in more detail, in order to measure overall shape information on a large-area subject, 3D shape information for each predefined partial region is acquired (1), and then the partial regions are 3D shape information on the entire region of the subject may be obtained (2) by attaching 3D shape information on the object using a stitching algorithm.

However, in the case of using such a prior art for an object having various curvatures, such as a free-form optical component, local distortion occurs according to the curvature of the corresponding region when measuring the shape of a partial region. It is difficult to guarantee the accuracy of the entire shape information obtained by stitching the shape information of the region. In particular, high measurement precision is required to evaluate the quality of a large-diameter optical system that requires very high processing precision, such as an imaging optical system that can be mounted on an earth observation satellite, and thus there are technical limitations in using such conventional technology.

In order to solve this problem, Korean Patent Registration No. 2,063,568 discloses a partial region shape measuring device (10 ) is posted (see FIG. 2). At this time, in order to acquire the interference fringe 15 without loss or appropriate, the radius of curvature (ROC) of the reference mirror 11 of the partial region shape measuring device 10 and the surface of the object 20 is the same or has a predetermined error. Must match within range. As shown in FIG. 3 , when the reference mirror 12 of the partial region shape measuring device 10 and the radius of curvature of the surface of the object 20 do not match outside the allowable error range, the obtained interference fringe 15 includes A loss area 17 appears, and as a result, a problem in that the accuracy of information of the entire shape obtained through stitching is lowered.

Japanese Patent Registration No. 5,424,581 Korean Registered Patent No. 2,063,568

In order to solve the above-mentioned problems, the present invention is a partial region shape measuring device having an extended radius of curvature capable of extending an error tolerance range in which the radius of curvature of the surface of a subject must match the reference mirror of the partial region shape measuring device. want to provide

In addition, the present invention provides a partial region shape measuring device having an extended radius of curvature capable of acquiring shape information on the partial region with high measurement precision even for a large-area test object having various curvatures such as free-form optical parts. want to do

Other objects of the present invention will become clearer through preferred embodiments described below.

According to one aspect of the present invention, a device for measuring the shape of a partial region having an extended radius of curvature includes: an incident unit for injecting light output from a light source into the device for measuring the shape of a partial region; an optical separation unit separating the incident light into reference light and measurement light; a reference light splitting unit configured to split the reference light incident into the optical splitting unit into a plurality of pieces; a plurality of reference mirrors having reflection surfaces formed according to predefined surface shape information and reflecting the plurality of reference lights incident from the reference light splitter toward the reference light splitter; a light receiving unit receiving interference light generated by the plurality of reference lights reflected from the plurality of reference mirrors and the reference light reflected from the surface of the partial region of the object under test; and a processing unit generating shape information about a partial region of the object to be inspected based on the interference light received by the light receiving unit.

Here, the plurality of reference mirrors may have different radii of curvature.

Here, the light source is a broadband light source, and interference regions of the coherent light may be spatially separated according to curvature radii of the plurality of reference mirrors.

Here, the reference mirror may be selected and configured based on the similarity between the basic surface shape information of the partial region of the object under test and the surface shape information of the reference mirror.

Here, the incident unit may include a focus controller that changes the focus of light incident into the partial region shape measurement device.

Here, the focus controller may control the focus of the incident light based on at least one of surface shape information of the base surface of the object under test and surface shape information of the reference mirror.

Here, the focus controller may control the focus of the incident light so that the reference light reflected from the reference mirror and the reference light reflected from the surface of the partial region of the object under test are output as parallel light toward the light receiver.

Here, the partial region shape measuring device may further include a telecentric optical unit configured on an optical path of the coherent light to acquire shape information having the same field-of-view (FOV).

According to the present invention, it is possible to expand an error tolerance range in which the radius of curvature of the reference mirror of the partial region shape measuring device and the surface of the object under test must match.

In addition, according to the present invention, shape information on a partial region can be obtained with high measurement accuracy even for a large-area test object having various curvatures, such as a free-form optical component.

1 is a view for explaining a partial aperture stitching technique according to the prior art;
Figures 2 and 3 Figure 3 is a view showing a partial region shape measuring device according to the prior art.
4 is a reference view for explaining an apparatus for measuring the shape of a partial region having an extended radius of curvature according to the present invention;
5 and 6 are detailed views illustrating an apparatus for measuring the shape of a partial region having an extended radius of curvature according to an embodiment of the present invention.

Since the present invention can apply various transformations and have various embodiments, specific embodiments will be illustrated in the drawings and described in detail in the detailed description. However, it should be understood that this is not intended to limit the present invention to specific embodiments, and includes all transformations, equivalents, and substitutes included in the spirit and scope of the present invention. In describing the present invention, if it is determined that a detailed description of related known technologies may obscure the gist of the present invention, the detailed description will be omitted.

Terms such as first and second may be used to describe various components, but the components should not be limited by the terms. These terms are only used for the purpose of distinguishing one component from another.

Terms used in this application are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise. In this application, the terms "include" or "have" are intended to designate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, but one or more other features It should be understood that the presence or addition of numbers, steps, operations, components, parts, or combinations thereof is not precluded. Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Hereinafter, an apparatus for measuring the shape of a partial region having an extended radius of curvature according to the present invention will be described in detail with reference to FIGS. 4 to 6 .

4 is a reference diagram for explaining a shape measuring device for a partial region having an extended curvature portion according to the present invention, and FIGS. 5 and 6 are a shape measuring device for a partial region having an extended curvature portion according to an embodiment of the present invention. It is a detailed diagram to explain.

Referring to FIG. 4 , the apparatus 200 for measuring the shape of a partial region having an extended radius of curvature measures the surface of the object 100 under examination using an optical measurement method to generate shape information. Here, the shape information may include 3D shape information on the surface of the object 100 under test.

The subject 100 according to the present invention is a measurement target of the partial area shape measuring device 200, and may correspond to a large-area optical component (eg, a 1000 mm diameter lens), but is not limited to size, type, or shape. should be interpreted as

The apparatus 200 for measuring the shape of a partial region according to the present invention measures shape information of a partial region of the object 100 under test, and stitches the shape information of the measured partial regions to determine the overall shape of the object 100 under test. information can be measured. Here, the partial region shape measuring device 200 may operate to sequentially measure the surfaces of a plurality of partial regions according to a predefined order, and may use a mechanical device (eg, a probe transfer device and a stage) for this operation. can be configured to include

5 and 6, the apparatus 200 for measuring the shape of a partial region having an extended radius of curvature according to the present invention includes an incident part 210, an optical separation part 220, and a plurality of reference mirrors 230 and 235. , a light receiving unit 240, a processing unit 250, and a reference light separating unit 270.

The incident unit 210 may inject light output from a light source (not shown) into the partial region shape measuring device 100 .

The light separation unit 220 may separate the light incident by the incident unit 210 into reference light and measurement light. Here, the reference light separated by the light separator 220 may be emitted toward the reference light separator 270 , and the measurement light may be emitted toward the object 100 under test. At this time, the reference beam separation unit 270 may separate incident reference beams into a plurality of beams and emit them toward the plurality of reference mirrors 230 and 235 .

The plurality of reference mirrors 230 and 235 are optical members having reflective surfaces formed according to predefined surface shape information, and reflect the incident reference light separated from the reference light splitter 270 toward the reference light splitter 270. is composed of

In one embodiment, the plurality of reference mirrors 230 and 235 are selected based on the similarity between the basic surface shape information of the partial region of the object 100 and the surface shape information of the plurality of reference mirrors 230 and 235. can be configured. Here, the basic surface shape information on the partial region is curvature information or 3D shape information on the previously stored partial region of the subject 100 (eg, surface shape information on each partial region of the subject generated in the preliminary design process). ) may correspond to That is, the plurality of reference mirrors 230 and 235 may be configured by selecting an optical member having curvature or shape information similar to the partial region to be measured. Here, the plurality of reference mirrors 230 and 235 may have different radii of curvature. As an extreme example, one reference mirror 230 may be a plane mirror and the remaining mirrors 235 may be free-form mirrors.

The light receiver 240 receives interference light generated by the reference light reflected from the plurality of reference mirrors 230 and 235 and the reference light reflected from the surface of the partial region of the object 100 under test. In this case, the light source is a broadband light source, and interference regions of the coherent light may be spatially separated according to the curvature radii of the plurality of reference mirrors 230 and 235 .

The processing unit 250 is connected to the light receiving unit 240, receives electrical signals or data corresponding to the interference light from the light receiving unit 240, and based on the received electrical signals or data, the partial region of the object 100 under test. Generates shape information for Meanwhile, the processing unit 250 according to the present invention is a computing device that generates surface shape information of the subject 100 according to a predefined data processing process, and should be construed as not being limited to its type and operation. The processing unit 250 described in the present invention may be composed of a combination of hardware and software according to the purpose of generating surface shape information of the subject 100, and any device configured according to this purpose is described in the present invention. It should be seen as corresponding to the processing unit 250 to do.

The apparatus 200 for measuring the shape of a partial region having an extended radius of curvature according to an embodiment of the present invention may further include a telecentric optical unit 260 configured on an optical path of coherent light. Here, the telecentric optical unit 260 is configured on the optical path of the coherent light to obtain shape information having the same field-of-view (FOV). More specifically, when the subject 100 corresponds to a large-area free-form optical component having various curvatures, as the partial region shape measuring device 200 includes the telecentric optical unit 260, Even if partial regions having different curvatures are measured, shape information of the partial regions having the same area and without distortion may be obtained.

The incident unit 210 may include a focus controller 211 that changes the focus of light incident into the partial region shape measuring device 200 having an extended radius of curvature. Here, the incident unit 210 may include an incident optical system 212 that determines the focus of light output from the light source, and the focus controller 211 controls the position of the incident optical system 212 to shape the partial region. A focus of light incident into the measuring device 200 may be varied.

On the other hand, the focus controller 211 according to the present invention is a control device capable of processing and outputting control signals and controlling the position of the incident optical system 212 according to the control signals. can be implemented in combination.

In one embodiment, the focus controller 211 transmits the reference light reflected from the plurality of reference mirrors 230 and 235 and the reference light reflected from the surface of the subregion of the object 100 to the light receiver 240 (or telecentric optical system). 260), it is possible to control the focus of incident light so that it is output as parallel light.

Here, the focus controller 211 may control the focus of incident light based on at least one of information on the basic surface shape of the subject 100 and information on the surface shape of the plurality of reference mirrors 230 and 235 . More specifically, as shown in FIG. 5 , when the subject 100 is flat, the focus controller 211 transmits the reference light reflected from the reference light and the reference mirror 230 that is a flat optical member to the light receiver ( 240), the position of the incident optical system 210 may be controlled. In this case, the shape of the surface of the object under test 100 may be the shape of the conjugate plane of the reference mirror 230 . In addition, as shown in FIG. 6, the object under test 100 corresponds to a free-form optical system (here, the shape of the surface of the object under test 100 may be the shape of the conjugate plane of the reference mirror 235). Yes), the focus controller 211 may control the position of the incident optical system 210 so that the reference light and the reference light reflected from the reference mirror 235, which is a free-form optical member, are emitted toward the light receiver 240. . More specifically, when the subject 100 corresponds to the free-form optical system, the focus controller 211 measures the object 100 while the partial area shape measurement device 200 moves and measures a plurality of partial areas. As the curvature is different for each partial region of , the focus of the output light may be controlled so that the reference light incident toward the light receiving unit 240 and the reference light become parallel light. In the partial region shape measuring device 200 according to the present invention, when the curvature of the free-shaped object 100 and the free-shaped reference mirror 235 having similar shape information do not match in a partial region (for example, , when some areas are flat), shape measurement is possible using another reference mirror 230, so the interference fringe signal can be prevented from being lost. It has the advantage that the shape can be measured. Here, the plurality of reference mirrors may be free-shaped optical members having different shape information.

According to various embodiments of the present invention, even when the subject 100 corresponds to a large-area free-form optical component having various curvatures, it corresponds to shape information (or shape information of a reference mirror) of each partial area to be measured. By controlling the focus of the incident light, the coherent light can be incident as parallel light toward the light receiving unit 240, and as the telecentric optical unit 260 is configured on the optical path of the coherent light, each has the same area It is possible to obtain distortion-free partial region shape information. Therefore, according to the present invention, even for a large-area test object having various curvatures, such as a free-form optical component, it is possible to obtain the shape information of the partial region with the same magnification and high measurement accuracy, and the shape information of the partial region obtained according to the present invention. The precision of the entire shape information obtained by stitching may have high reliability compared to the prior art.

The preferred embodiments of the present invention described above have been disclosed for illustrative purposes, and those skilled in the art with ordinary knowledge of the present invention will be able to make various modifications, changes, and additions within the spirit and scope of the present invention, and these modifications, changes, and The additions should be viewed as falling within the scope of the following claims.

100: subject
200: partial area shape measurement device
210: entrance part
211: focus control
212: incident optical system
220: optical separation unit
230: reference mirror
240: optical receiver
250: processing unit
260: telecentric optical unit
270: reference light separator

Claims (8)

A partial region shape measuring device for generating shape information on a partial region of a subject,
an incident unit for injecting light output from a light source into the partial region shape measuring device;
an optical separation unit separating the incident light into reference light and measurement light;
a reference light splitting unit configured to split the reference light incident from the optical splitting unit into a plurality of pieces;
a plurality of reference mirrors having reflection surfaces formed according to predefined surface shape information and reflecting the plurality of reference lights incident from the reference light splitter toward the reference light splitter;
a light receiving unit receiving interference light generated by the plurality of reference lights reflected from the plurality of reference mirrors and the reference light reflected from the surface of the partial region of the object under test; and
a processing unit generating shape information about a partial region of the object to be inspected based on the interference light received by the light receiving unit;
The plurality of reference mirrors,
A partial region shape measuring device having an extended radius of curvature, characterized in that it has different radii of curvature. delete According to claim 1,
The light source,
A partial region shape measuring device having an extended radius of curvature, characterized in that the broadband light source and the interference region of the interference light is spatially separated in accordance with the radius of curvature of the plurality of reference mirrors. According to claim 1,
The reference mirror,
A partial region shape measuring device having an extended radius of curvature, characterized in that it is selected and configured based on the similarity between the basic surface shape information of the partial region of the subject and the surface shape information of the reference mirror. According to claim 1,
The entrance part,
A partial region shape measuring device having an extended curvature radius range, characterized in that it comprises a focus control unit for changing the focus of light incident into the partial region shape measuring device According to claim 5,
The focus controller,
and controlling the focus of the incident light based on at least one of the basic surface shape information of the object under test and the surface shape information of the reference mirror. According to claim 6,
The focus control unit
The part having an extended radius of curvature characterized in that the focus of the incident light is controlled so that the reference light reflected from the reference mirror and the reference light reflected from the surface of the partial region of the object under test are output as parallel light toward the light receiving unit. area shape measurement device. The method of claim 1, wherein the partial region shape measuring device
A partial region shape having an extended radius of curvature, characterized in that it further comprises; a telecentric optical unit configured on the optical path of the coherent light to acquire shape information having the same field-of-view (FOV). measuring device.

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