JP2018063157A - Shape measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shape measuring device that can improve reliability of distance image data.SOLUTION: A distance image creation part 21 creates, on the basis of measurement light received from a light receiving part, distance information on an area corresponding to every pixel of the light receiving part and creates distance image data including the distance information corresponding to the plurality of pixels. A determination part 22 determines whether height data corresponding to a pixel to be determined is calculated on the basis of stray light on the basis of the maximum amount of light received by the pixel to be determined, height data corresponding to the pixel to be determined, maximum amount of light received by pixels on the periphery of the pixel to be determined, and height information corresponding to the pixels on the periphery of the pixel to be determined.SELECTED DRAWING: Figure 14

Description

  The present invention relates to a shape measuring apparatus for measuring the shape of a measurement object.

  There is a shape measuring device that irradiates the surface of a measurement object with light and measures the surface shape of the measurement object based on the reflected light. As an example of such a shape measuring apparatus, Patent Document 1 describes a coherence scanning interferometer that performs measurement by an interferometry. In this coherence scanning interferometer, light generated from a light source is divided into measurement light irradiated on an object and reference light irradiated on a reference mirror. The measurement light reflected by the object and the reference light reflected by the reference mirror are superimposed and detected by the camera. An image is acquired by the camera while the optical system including the light source and the camera is moved relative to the object. The surface height of the object is calculated based on the interval between the interference fringes in the acquired image.

JP2013-83649A

  In the shape measuring apparatus as described above, each pixel of the light receiving unit (camera) receives light reflected by each region of the surface of the measurement object. However, depending on the shape and reflectance of the surface of the measurement object, reflected light from a region different from the corresponding region may be incident on each pixel as stray light. Therefore, the reliability of the acquired image is lowered, and there is a possibility that an incorrect surface height is calculated.

  An object of the present invention is to provide a shape measuring device capable of improving the reliability of distance image data.

  (1) A shape measuring apparatus according to the present invention is a shape measuring apparatus that measures the surface shape of a measurement object, and includes a light projecting unit that emits light and a light receiving unit that includes a plurality of pixels arranged two-dimensionally. And, based on the measurement light received by the light receiving unit, an optical system that guides the light emitted by the light projecting unit to the measurement target as measurement light, guides the measurement light reflected by the measurement target to the light receiving unit, Distance information generating means for generating distance information of a corresponding region of the measurement object for each pixel, generating distance image data including a plurality of distance information corresponding to the generated plurality of pixels, and one pixel of the light receiving unit Corresponds to one pixel based on received light amount, distance information corresponding to one pixel, received light amount of each of one or more pixels around one pixel, and one or more distance information corresponding to one or more pixels Whether or not distance information to be generated is generated based on stray light And a constant section.

  In this shape measuring apparatus, the measurement light reflected by the measurement object is received by a light receiving unit including a plurality of pixels arranged two-dimensionally. In this case, the measurement light reflected by the corresponding region of the measurement object is incident on each pixel of the light receiving unit. Based on the measurement light received by the light receiving unit, distance information of the region of the measurement object corresponding to each pixel is generated, and distance image data including distance information corresponding to a plurality of pixels is generated.

  In some cases, measurement light reflected in a region different from the corresponding region may be incident on each pixel of the light receiving unit as stray light. In that case, the distance information may be erroneously generated based on the stray light. Therefore, the amount of light received by one pixel of the light receiving unit, distance information corresponding to one pixel, the amount of light received by one or more pixels around one pixel, and one or more distance information corresponding to one or more pixels. Based on the above, it is determined whether distance information corresponding to one pixel has been generated based on stray light. Thereby, the reliability of the distance information corresponding to each pixel can be determined. Therefore, the reliability of the distance image data can be improved.

  (2) The shape measuring apparatus further includes a determination criterion receiving unit that receives adjustment of the determination criterion, and the determination unit determines that the distance information corresponding to one pixel is stray light based on the determination criterion adjusted by the determination criterion receiving unit. It may be determined whether or not it has been generated based on the above. In this case, the user can adjust the determination criterion so that the determination is appropriately performed by the determination unit.

  (3) The determination means is based on the degree of coincidence between the distance information corresponding to one pixel and the one or more distance information corresponding to one or more neighboring pixels, and the amount of light received by each of the one or more neighboring pixels. It may be determined whether distance information corresponding to one pixel is generated based on stray light. In this case, the reliability of distance information can be determined appropriately.

  (4) The shape measuring device calculates a measurement value related to the shape of the measurement object based on the distance information determined not to be generated based on the stray light by the determination unit, and is generated based on the stray light by the determination unit. You may further provide the calculation means which does not calculate a measured value based on the determined distance information. In this case, the measurement value is prevented from being calculated based on incorrect distance information.

  (5) The shape measuring device includes a reference body, a movable part to which at least one of the optical system and the reference body is attached, a support part that supports the movable part so as to be able to reciprocate, and a relative position of the movable part with respect to the support part. A position detecting unit for detecting, the light projecting unit emits light having a plurality of peak wavelengths, and the optical system guides the light emitted by the light projecting unit to the reference body as reference light, and the measurement object The interference light between the measurement light reflected by and the reference light reflected by the measurement object is generated, the generated interference light is guided to the light receiving unit, and the movable unit reciprocally moves to reference the optical path length of the measurement light and the reference light. The image generation means may generate the distance image data based on the interference light received by the light receiving unit and the relative position detected by the position detection unit by changing a difference from the optical path length of the light.

  In this case, the interference pattern of the received light amount that varies depending on the difference between the optical path length of the measurement light and the optical path length of the reference light is obtained from the plurality of pixels of the light receiving unit. Since the measurement light and the reference light have a plurality of peak wavelengths, the interference pattern of the amount of received light does not show spatial periodicity. Therefore, distance information corresponding to a plurality of pixels of the light receiving unit can be generated based on the relative position of the movable unit with respect to the support unit detected by the position detection unit and the amount of light received by each pixel of the light receiving unit.

  According to the present invention, it is possible to improve the reliability of distance image data.

It is a block diagram which shows the structure of the shape measuring apparatus which concerns on one embodiment of this invention. It is a schematic diagram of a measurement head. It is a figure which shows the vibration of a movable part. It is a figure which shows the light reception amount distribution which should be acquired by the light-receiving part about arbitrary pixels. It is a figure which shows an example of the screen displayed on the display part of FIG. It is a figure for demonstrating the setting of search conditions. It is a figure for demonstrating the example of a setting of measurement conditions. It is a figure for demonstrating the measurement process with respect to measurement image data. It is a figure for demonstrating the measurement process with respect to measurement image data. It is a schematic diagram for demonstrating the example of a stray light. It is a figure which shows the light reception amount of a pixel. It is a schematic diagram for demonstrating stray light determination. It is a figure which shows the example of a filter level adjustment screen. It is a functional block diagram which shows the function implement | achieved by a control board and a memory | storage part. It is a flowchart which shows an example of operation | movement of CPU of a control board.

  Hereinafter, an optical area displacement meter according to an embodiment of the present invention will be described in detail with reference to the drawings.

(1) Basic Configuration of Shape Measuring Device FIG. 1 is a block diagram showing a configuration of a shape measuring device according to an embodiment of the present invention. As shown in FIG. 1, the shape measuring apparatus 300 includes a measuring head 100 and a processing apparatus 200. The measurement head 100 is, for example, an optical displacement meter, and includes a support structure 110, a casing unit 120, a measurement unit 130, a reciprocating mechanism 140, a drive unit 150, a control board 160, and a communication unit 170.

  The support structure 110 has an L-shaped longitudinal section and includes an installation part 111 and a holding part 112. The installation part 111 and the holding part 112 are made of metal, for example. The installation unit 111 has a horizontal flat plate shape and is installed on the installation surface. The measuring object S is placed on the upper surface of the installation unit 111. In this example, an X axis and a Y axis that are parallel to and orthogonal to the upper surface of the installation unit 111 are defined, and a Z axis that is perpendicular to the upper surface of the installation unit 111 is defined. In FIG. 1, arrows indicating the directions of the X axis, the Y axis, and the Z axis are attached.

  The holding part 112 is provided so as to extend upward from one end of the installation part 111. The casing unit 120 is held by the holding unit 112 of the support structure 110. The casing 120 has a rectangular parallelepiped shape, and houses the measuring unit 130, the reciprocating mechanism 140, the driving unit 150, the control board 160, and the communication unit 170.

  The measurement unit 130 includes optical elements such as a light projecting unit, a light receiving unit, a lens, and a mirror. The measurement unit 130 is attached to the reciprocating mechanism 140 except for some elements such as the mirror 11 of FIG. The reciprocating mechanism 140 reciprocates (vibrates) in one direction with respect to a support portion 125 of FIG. The drive unit 150 is an actuator, and is a voice coil motor in this example.

  The control board 160 includes a CPU (Central Processing Unit) 160a. The control board 160 acquires measurement data described later from the measurement unit 130, generates pixel data based on the acquired measurement data, and generates image data. Image data is a set of a plurality of pixel data. The control board 160 supplies the generated image data to the processing device 200 and controls the operations of the measurement unit 130, the reciprocating mechanism 140, and the driving unit 150 based on instructions from the processing device 200.

  Communication unit 170 includes a communication interface. The same applies to a communication unit 250 of the processing device 200 described later. The communication unit 170 transmits and receives various data and commands between the measurement head 100 and the processing device 200 through the communication unit 250. Details of the measuring head 100 will be described later.

  The processing device 200 includes a control unit 210, a storage unit 220, an operation unit 230, a display unit 240, and a communication unit 250. The control unit 210 includes a CPU, for example. The storage unit 220 includes, for example, a ROM (read only memory), a RAM (random access memory), and an HDD (hard disk drive). The storage unit 220 stores a system program. The storage unit 220 is used for storing various data and processing data.

  Based on the system program stored in the storage unit 220, the control unit 210 gives a command for controlling the operations of the measurement unit 130, the reciprocating mechanism 140, and the drive unit 150 of the measurement head 100 to the control board 160. In addition, the control unit 210 acquires image data from the control board 160 and stores it in the storage unit 220. Further, the control unit 210 measures a portion designated by the user on the image based on the image data.

  The operation unit 230 includes a mouse, a touch panel, a pointing device such as a trackball or a joystick, and a keyboard, and is operated by a user to give an instruction to the control unit 210. The display unit 240 includes, for example, an LCD (liquid crystal display) panel or an organic EL (electroluminescence) panel. The display unit 240 displays an image based on the image data stored in the storage unit 220, a measurement result, and the like. The communication unit 250 communicates with the measurement head 100 as described above. The communication unit 250 can communicate with an external device such as a PLC (programmable logic controller).

(2) Configuration of Measurement Unit FIG. 2 is a schematic diagram of the measurement head 100 mainly showing the configuration of the measurement unit 130. As shown in FIG. 2, a support part 125 is accommodated in the housing part 120. The support part 125 may be formed integrally with the housing part 120 or may be a part of the housing part 120. The reciprocating mechanism 140 includes a movable portion 141 that can vibrate in parallel with the support portion 125 in one direction. In FIG. 2, the vibration direction of the movable portion 141 is indicated by a thick arrow. In the example of FIG. 2, the vibration direction of the movable part 141 is the vertical direction.

  The measuring unit 130 includes a light projecting unit 1, light receiving units 2 and 3, a plurality of lenses 4 to 8, a plurality of mirrors 9 to 11, a beam splitter 12, an anamorphic prism pair 13, a position detecting unit 14, and a guide light source 15. Including. Part of the mirror 11 and the position detection unit 14 of the measurement unit 130 are attached to the support unit 125. On the other hand, the measurement unit 130 excluding a part of the mirror 11 and the position detection unit 14 is attached to the movable unit 141.

  The light projecting unit 1 includes, for example, an SLD (super luminescent diode) and emits light. The light emitted from the light projecting unit 1 is referred to as outgoing light L0. The coherence of the emitted light L0 is relatively low. Specifically, the coherence of the emitted light L0 is higher than the light emitted from the LED (light emitting diode) or white light, and lower than the coherence of the laser light. Therefore, the emitted light L0 has a plurality of peak wavelengths. The lens 4 is a collimator lens. The outgoing light L0 is collimated by passing through the lens 4 and shaped so as to have a circular cross section by passing through the anamorphic prism pair 13.

  A part of the emitted light L0 is reflected without passing through the anamorphic prism pair 13. The outgoing light L0 reflected by the anamorphic prism pair 13 is received by the light receiving unit 3, and a received light signal indicating the amount of received light is output to the control board 160 (FIG. 1). Based on the light reception signal output from the light receiving unit 3, the amount of the emitted light L 0 is measured by the control board 160. When the measured amount of the emitted light L0 indicates an abnormal value, the operation of the light projecting unit 1 is stopped by the control board 160. In this way, the amount of emitted light can be managed using the emitted light that is not used for measurement.

  The reflectivity of the mirror 9 has wavelength selectivity. Specifically, the mirror 9 has a high reflectance (preferably 100%) in the wavelength region of the outgoing light L0, and has a reflectance lower than 100% in the wavelength region of the guide light G described later. The outgoing light L0 that has passed through the anamorphic prism pair 13 is reflected by the mirror 9, and then enters the beam splitter 12 while being condensed by passing through the lens 5.

  A part of the emitted light L0 is reflected by the beam splitter 12 and the remaining part of the emitted light L0 is transmitted through the beam splitter 12. The outgoing light L0 reflected by the beam splitter 12 and the outgoing light L0 transmitted through the beam splitter 12 are referred to as measurement light L1 and reference light L2, respectively.

  The lens 6 is an objective lens. The measurement light L1 is collimated by passing through the lens 6. At this time, the spot diameter of the measurement light L1 is relatively large, for example, 4 mm or 10 mm. Thereafter, the measurement light L1 travels in substantially the same direction as the vibration direction of the movable portion 141, and is irradiated to a relatively large circular region of the measurement object S. A part of the measurement light L1 reflected by the measurement object S enters the beam splitter 12 while being condensed by passing through the lens 6.

  The mirror 10 is a so-called reference mirror. The reference light L <b> 2 is collimated by passing through the lens 7 and is applied to the mirror 10. The reference light L2 reflected by the mirror 10 enters the beam splitter 12 while being condensed by passing through the lens 7. The measurement light L1 incident on the beam splitter 12 interferes with the reference light L2, and is guided to the light receiving unit 2 as interference light L3. The operation of the light receiving unit 2 will be described later.

  The position detection unit 14 includes reading units 14a and 14b, a scale 14c, and a magnet 14d. The reading units 14 a and 14 b are attached to the movable unit 141, and the scale 14 c and the magnet 14 d are attached to the support unit 125. The scale 14c has a plurality of scales and is formed of glass extending in one direction. The reading unit 14a is arranged to face a part of the scale 14c. The reading unit 14a includes a light projecting element and a light receiving element, and detects the relative position of the movable unit 141 with respect to the support unit 125 by optically reading the scale of the opposing scale 14c.

  The reading unit 14b is a Hall element and is arranged to detect magnetism by the magnet 14d. In the present embodiment, the origin of the portion of the scale 14c read by the reading unit 14a when the reading unit 14b detects the maximum magnetism. The origin of the scale 14c may be updated as appropriate when the measuring head 100 is activated or at other times. Based on the detection results of the reading units 14a and 14b, the absolute position of the movable unit 141 can be specified.

  In the present embodiment, the reading units 14a and 14b are attached to the movable unit 141, and the scale 14c and the magnet 14d are attached to the support unit 125, but the present invention is not limited to this. The reading units 14 a and 14 b may be attached to the support unit 125, and the scale 14 c and the magnet 14 d may be attached to the movable unit 141.

  In the present embodiment, the reading unit 14a optically detects the position of the movable unit 141, but the present invention is not limited to this. The reading unit 14a may detect the position of the movable unit 141 by, for example, other mechanical, electrical, or magnetic methods. Furthermore, when the reading unit 14a can detect the absolute position of the movable unit 141, or when it is not necessary to detect the absolute position of the movable unit 141, the position detection unit 14 includes the reading unit 14b and the magnet. 14d may not be included.

  The guide light source 15 is a laser light source that emits laser light having a wavelength in the visible region (red region in this example). The laser light emitted from the guide light source 15 is referred to as guide light G. In FIG. 2, the guide light G is illustrated by a one-dot chain line. As described above, since the reflectance of the mirror 9 is lower than 100% in the wavelength region of the guide light G, a part of the guide light G is transmitted through the mirror 9 and the remaining part of the guide light G is the mirror 9. It is reflected by. The guide light G transmitted through the mirror 9 and the guide light G reflected by the mirror 9 are referred to as a first guide light G1 and a second guide light G2, respectively.

  The first guide light G1 is collected by passing through the lens 5 and reflected by the beam splitter 12, thereby being superimposed on the measurement light L1. As a result, the first guide light G1 travels in substantially the same direction as the vibration direction of the movable portion 141, is collimated by passing through the lens 6, and then irradiates the measurement object S.

  The second guide light G2 travels in a direction crossing the first guide light G1 by being reflected by the mirror 11 attached to the support portion 125. When the movable portion 141 is at a predetermined position in the vibration direction (for example, near the origin of the scale 14c), the first guide light G1 and the second guide light G2 intersect at the focal position of the light receiving portion 2. A mirror 11 is arranged.

  Thus, the guide part 16 is comprised by the mirror 9, the mirror 11, the beam splitter 12, and the guide light source 15. FIG. According to this configuration, the user arranges the surface of the measurement object S at a position where the first guide light G1 and the second guide light G2 intersect, so that the surface of the measurement object S is received by the light receiving unit. It can be easily located at the two focal points.

  In the present embodiment, the guide light G is emitted by the guide light source 15 during a non-measurement period t2 in FIG. 3 to be described later, and not during the measurement period t1. Therefore, the measurement of the measuring object S is prevented from being affected by the guide light G. On the other hand, when the guide light G does not affect the measurement of the measurement object S, such as when the light receiving unit 2 is configured not to detect light in the wavelength band of the guide light G, the guide light source 15 is used for the measurement period t1. Alternatively, the guide light G may be controlled to be emitted.

  In the present embodiment, the guide unit 16 is arranged so that the first and second guide lights G1 and G2 intersect at the focal point of the light receiving unit 2, but the present invention is not limited to this. The guide unit 16 includes a pattern of the first guide light G1 and the second guide light G2 projected onto the surface of the measurement target S when the surface of the measurement target S is at the focal point of the light receiving unit 2. The pattern may be arranged to have a specific positional relationship.

(3) Operation of Measurement Unit The movable unit 141 is periodically oscillated in parallel with one direction with respect to the support unit 125 in synchronization with the sampling signal by the driving unit 150. The sampling signal may be generated inside the processing apparatus 200 (FIG. 1), or may be given to the movable unit 141 from the outside of the processing apparatus 200. FIG. 3 is a diagram illustrating the vibration of the movable portion 141. The horizontal axis in FIG. 3 indicates time and indicates the position of the movable portion 141.

  As shown in FIG. 3, in the present embodiment, the position of the movable portion 141 changes in a sinusoidal shape. Here, the measurement object S is measured during a part of the period in which the position of the movable portion 141 changes, and the measurement object S is not measured during the other period. A period during which measurement of the measuring object S is performed is referred to as a measurement period t1, and a period during which measurement is not performed is referred to as a non-measurement period t2. In the present embodiment, a period corresponding to a substantially linearly changing portion of the sine curve of FIG. 3 is assigned as the measurement period t1, and a period corresponding to the vicinity of the inflection portion of the sine curve is a non-measurement period t2. Assigned as.

  The control board 160 (FIG. 1) controls the light reception timing of the light receiving unit 2 based on the sampling signal. The light receiving unit 2 includes a two-dimensional area sensor in which a plurality of pixels are arranged in the vertical direction and the horizontal direction. In the present embodiment, the area sensor has 300 pixels in the vertical direction and 300 pixels in the horizontal direction, and the total number of pixels is 90000. Thereby, the interference light L3 having a relatively large spot diameter can be received. Based on the control by the control board 160, the light receiving unit 2 detects the received light amount for each position of the movable unit 141 for each pixel during the measurement period t1. On the other hand, the light receiving unit 2 does not detect the amount of received light during the non-measurement period t2.

  4A and 4B are diagrams showing the received light amount distribution to be acquired by the light receiving unit 2 for an arbitrary pixel. 4A and 4B, the horizontal axis indicates the difference between the optical path length of the measurement light L1 and the optical path length of the reference light L2, and the vertical axis indicates the amount of received light detected. Hereinafter, the difference between the optical path length of the measurement light L1 and the optical path length of the reference light L2 is referred to as an optical path length difference. When the position of the movable portion 141 changes, the optical path length of the reference light L2 does not change, but the optical path length of the measurement light L1 changes, so that the optical path length difference changes.

  If the output light L0 has high coherence and the output light L0 has a single peak wavelength λ, the measurement light L1 and the reference light L2 reinforce each other when the optical path length difference is n × λ. When the optical path length difference is (n + 1/2) × λ, they weaken each other. Here, n is an arbitrary integer. For this reason, as shown in FIG. 4A, the amount of received light varies between the maximum value and the minimum value every time the optical path length difference changes by half the peak wavelength.

  On the other hand, when the outgoing light L0 has a plurality of peak wavelengths, the optical path length difference when the measurement light L1 and the reference light L2 strengthen each other and weaken each other differs for each peak wavelength. Therefore, a received light amount distribution obtained by adding the same received light amount distribution as in FIG. 4A, which differs for each peak wavelength, is acquired. Specifically, as shown by a solid line in FIG. 4B, a plurality of peaks appear in the received light amount distribution in the range of a small optical path length difference. The peak received light amount when the optical path length difference is 0 is maximized, and the peak received light amount decreases as the optical path length difference increases. The range of the optical path length difference where the peak appears is wider as the coherence of the emitted light L0 is higher.

  In the present embodiment, the light receiving unit 2 specifies an envelope of the received light amount distribution as shown by a dotted line in FIG. 4B, and the control board 160 uses the data indicating the specified envelope as measurement data. give. The control board 160 specifies the time point when the optical path length difference becomes 0 and the maximum received light amount Im based on the envelope indicated by the acquired measurement data. Here, since the coherence of the emitted light L0 is higher than the coherence of the light emitted by the LED, a peak appears in a wider range of optical path lengths than when the LED is used. Therefore, even when the frequency of detecting the amount of received light is reduced, the time when the optical path length difference becomes 0 and the maximum amount of received light Im can be accurately specified. Thereby, the measurement can be speeded up.

  Further, the control board 160 specifies the position of the movable unit 141 at the time point specified by the light receiving unit 2 based on the detection result of the position detection unit 14 (FIG. 2). Furthermore, the control board 160 generates pixel data based on the specified position of the movable part 141 and the acquired maximum received light amount Im. Pixel data generated based on the position of the movable portion 141 is referred to as height data, and pixel data generated based on the maximum received light amount Im is referred to as luminance data.

  Note that a threshold value (hereinafter referred to as a received light amount threshold value) for determining whether or not the acquired maximum received light amount is valid may be set. Due to various factors, there is a possibility that the maximum amount of received light is caused by noise rather than the reflected light from the measuring object S. The maximum amount of light received due to noise is often relatively small. Therefore, when the acquired maximum received light amount is smaller than the received light amount threshold value, it is determined that it is the maximum received light amount due to noise, and height data is not generated. Thereby, generation of height data with low reliability is suppressed. Further, the user may be able to arbitrarily adjust the received light amount threshold value.

  The control board 160 generates image data based on the plurality of pixel data. Image data generated based on the height data is referred to as height image data, and image data generated based on the luminance data is referred to as luminance image data. The height image data indicates the shape (height) of each part of the surface of the measuring object S, and the luminance image data indicates the luminance of each part of the surface of the measuring object S. The control board 160 gives the generated height image data and luminance image data to the processing device 200 (FIG. 1).

  The display unit 240 in FIG. 1 displays a height image based on the height image data, and displays a luminance image based on the luminance image data. The height image represents, for example, the difference in height of each part of the surface of the measurement object S by the difference in color. The luminance image represents, for example, a difference in luminance on the surface of the measuring object S by a difference in color. In addition, a blend image including a height image component and a luminance image component may be displayed based on the height image data and the luminance image data.

  FIG. 5 is a diagram illustrating an example of a screen displayed on the display unit 240 of FIG. The screen of FIG. 5 includes an image display unit 240a and a measurement value display unit 240b. A height image, a luminance image, or a blend image is displayed on the image display unit 240a. The measurement value display unit 240b displays a measurement value calculated based on the height image data.

(4) Measurement Example In this example, height image data and luminance image data of a reference object corresponding to the measurement object S are acquired in advance and stored in the storage unit 220 in FIG. The reference object has the same design as the measurement object S, and preferably has a higher dimensional accuracy than the measurement object S with respect to the design value.

  Hereinafter, the height image data and the luminance image data of the reference object are collectively referred to as reference image data, and the height image, the luminance image, and the blend image represented by the reference image data are collectively referred to as a reference image. The height image data and luminance image data of the measuring object S are collectively referred to as measurement image data, and the height image, luminance image, and blend image represented by the measurement image data are collectively referred to as measurement images. Further, in the following description, measurement means obtaining height image data and luminance image data, and measurement means obtaining measurement values such as dimensions.

  Various settings are performed using the reference image data, and the settings are stored in the storage unit 220 of FIG. 1 as measurement setting information. Based on the stored measurement setting information, measurement processing for measurement image data is performed.

  As settings for the reference image data, there are a search condition setting and a measurement condition setting. The search condition is a condition for performing a pattern search on the measurement image data. The pattern search is a process for detecting a designated pattern. FIG. 6 is a diagram for explaining setting of search conditions. FIG. 6A shows an example of a reference image displayed on the image display unit 240a. The reference image MI in FIG. 6A includes a reference object Sa.

  As shown in FIG. 6B, in the reference image MI displayed on the image display unit 240a, the pattern area T1 and the search area T2 are set using the designation frames C1 and C2. In this example, rectangular designated frames C1 and C2 are used, but the designated frames C1 and C2 may have other shapes such as a triangle or a circle. Further, the pattern region T1 and the search region T2 may be set by other methods such as coordinate input.

  The user can adjust the position, orientation, and size of the designation frames C1, C2 by operating the operation unit 230 of FIG. The area surrounded by the designated frame C1 is set as the pattern area T1, and the area surrounded by the designated frame C2 is set as the search area T2. Based on the reference image data, pattern information including height information and luminance information in the pattern region T1 is acquired. The height information is a set of height data, and the luminance information is a set of luminance data. The acquired pattern information is stored in the storage unit 220 as measurement setting information. Further, the relative position of the pattern area T1 and the relative position of the search area T2 in the reference image MI are stored in the storage unit 220 as measurement setting information.

  FIG. 7 is a diagram for explaining an example of setting measurement conditions. In the example of FIG. 7, the reference target region T3 is set for the reference image MI using a rectangular designation frame C3. The reference target region T3 is a region to be measured. The user can adjust the position, orientation, and size of the designated frame C3 by operating the operation unit 230 of FIG. A region surrounded by the designation frame C3 is set as the reference target region T3. The designated frame C3 may have a shape other than a rectangle, and the reference target region T3 may be set by other methods such as coordinate input. The relative position of the reference target region T3 in the reference image is stored in the storage unit 220 as measurement setting information.

  Next, a measurement process for measurement image data when search conditions and measurement conditions are set as shown in FIGS. 6 and 7 will be described. 8 and 9 are diagrams for explaining measurement processing for measurement image data. FIG. 8A shows an example of a measurement image displayed on the image display unit 240a. The measurement image DI in FIG. 8A includes a measurement object S corresponding to the reference object Sa.

  First, a pattern search is performed on measurement image data based on pattern information stored as measurement setting information. In the example of FIG. 8B, the region having the highest degree of coincidence with the pattern region T1 (FIG. 6B) of the reference image MI from the measurement image DI is detected as the feature region T1A. In this example, the search area T2A of the measurement image DI is specified based on the position of the set search area T2 (FIG. 6B). The relative position of the search area T2A in the measurement image DI is the same as the relative position of the search area T2 in the reference image MI. The feature area T1A is detected in the set search area T2A. In this way, the time required for the pattern search can be shortened by limiting the area to be detected in advance. When it is not necessary to shorten the time or when it is difficult to specify the area to be detected, the pattern search is performed on the entire measurement image DI without setting the search area T2 in the reference image MI. It may be done.

  Next, as shown in FIG. 9, in the measurement image DI, a measurement target region T3A corresponding to the reference target region T3 in FIG. 7 is specified. In this case, the measurement target region T3A is set so that the relative positional relationship between the feature region T1A and the measurement target region T3A in the measurement image DI is equal to the positional relationship between the pattern region T1 and the reference target region T3 in the reference image MI. Is set.

  Subsequently, based on the height image data of the measurement image DI, a measurement value related to the height of the surface portion of the measurement object S corresponding to the measurement object region T3A is calculated. The measurement value includes, for example, a maximum height, a minimum height, an average height, or a difference between the maximum height and the minimum height (hereinafter referred to as a peak-to-peak height). Moreover, these measured values may be displayed on the measured value display part 240b (FIG. 5).

  Further, it may be determined whether or not the measurement value of the measuring object S is within a predetermined allowable range (hereinafter referred to as tolerance determination). For example, the upper limit value and the lower limit value of the allowable range are determined based on the measurement value of the reference object Sa. The determination result is displayed on, for example, the measurement value display unit 240b in FIG. 7 and is output to an external device such as a PLC (programmable logic controller) through the communication unit 250 in FIG.

(5) Stray light The plurality of pixels of the light receiving unit 2 in FIG. The measurement light L1 reflected by the corresponding region is incident on each pixel as interference light. Hereinafter, stray light refers to light reflected by a region other than the region corresponding to the pixel among the light corresponding to each pixel. As described above, the time point at which the optical path length difference becomes 0 is specified based on the change in the amount of light received by each pixel, and the corresponding region is determined based on the relative position of the movable unit 141 with respect to the support unit 125 at that time. Height data is generated.

  Depending on the shape and reflectance of the surface of the measurement object S, the measurement light L1 reflected from one or more pixels in a region different from the corresponding region is incident as stray light. When the intensity of the stray light is large, the time point at which the optical path length difference becomes 0 may be erroneously specified. In that case, incorrect height data is generated.

  FIG. 10 is a schematic diagram for explaining an example of stray light. In FIG. 10, the lenses 6 and 8 and the beam splitter 12 are schematically shown as an optical system OS. For ease of understanding, the reference light L2 in FIG. 2 is not shown.

  In the example of FIG. 10, the measuring object S has surfaces P1 and P2 having different heights. The plane P1 includes a region R1, and the plane P2 includes a region R2. When viewed from the light receiving unit 2, the region R1 and the region R2 are adjacent to each other. The region R1 corresponds to the pixel E1 of the light receiving unit 2, and the region R2 corresponds to the pixel E2 of the light receiving unit 2. The surfaces P1 and P2 have different reflectances, and the reflectance of the surface P2 is higher than the reflectance of the surface P1.

  The measurement light L11 reflected by the region R1 is mainly incident on the pixel E1 through the optical system OS, and the measurement light L12 reflected by the region R is mainly incident on the pixel E2 through the optical system OS. Further, as indicated by a dotted arrow in FIG. 10, a part of the measurement light L12 reflected by the region R2 enters the pixel E1.

  Since the reflectance of the surface P2 is higher than the reflectance of the surface P1, the intensity of the measurement light L12 incident on the pixel E1 may be higher than the intensity of the measurement light L11 incident on the pixel E1. In this case, the peak due to the incidence of the measurement light L12 is included in the amount of light received by the pixel E1.

  FIG. 11 is a diagram showing the amount of light received by the pixel E1 in the example of FIG. In FIG. 11, the horizontal axis indicates the relative position of the movable portion 141 with respect to the support portion 125 in FIG. 2, and the vertical axis indicates the amount of received light. In the example of FIG. 11, at the relative positions PN1 and PN2, two peaks PK1 and PK2 appear in the envelope of the amount of received light. The relative position PN1 corresponds to a position where the optical path length difference between the measurement light L11 and the reference light in FIG. 10 is 0, and the relative position PN2 is an optical path length difference between the measurement light L12 and the reference light in FIG. It corresponds to the position. The maximum light reception Im2 at the peak PK2 is larger than the maximum light reception amount Im1 at the peak PK1. In this case, height data is generated based on the relative position PN2. That is, the generated height data indicates not the height of the region R1 corresponding to the pixel E1, but the height of the region R2 corresponding to the pixel E2.

  As described above, in the example of FIG. 10, a part of the measurement light L12 reflected by the region R2 of the surface P2 is incident on the pixel E1 as stray light, and as a result, erroneous height data is generated. In the present embodiment, since the plurality of pixels of the light receiving unit 2 are two-dimensionally arranged, the measurement light L1 reflected from each region different from the corresponding region is likely to be incident as stray light. For this reason, errors in height data are likely to occur.

  Note that, by increasing the above-described threshold value of received light amount, generation of erroneous height image data due to stray light is suppressed. However, if the maximum received light amount is smaller than the received light amount threshold value, the maximum received light amount is invalidated unconditionally. Therefore, if the reflectance of the surface of the measuring object S is low, there is a high possibility that height data indicating the actual height of the measuring object cannot be obtained.

(6) Stray Light Determination In the present embodiment, stray light determination is performed for each pixel of the light receiving unit 2 to determine whether the generated height data is generated based on stray light. FIG. 12 is a schematic diagram for explaining stray light determination. FIG. 12 shows a plurality of pixels arranged two-dimensionally.

  In the example of FIG. 12, a pixel to be determined (hereinafter referred to as a target pixel) is a hatched pixel EA. In this case, the maximum received light amount of the target pixel EA and the height data corresponding to the target pixel EA are acquired. Also, a plurality of pixels (hereinafter referred to as peripheral pixels) located around the target pixel EA are specified. In this example, eight peripheral pixels EB surrounding the target pixel EA and 16 peripheral pixels EC surrounding the eight peripheral pixels EB are specified. The maximum received light amount of each of the specified peripheral pixels EB and EC and the height data corresponding to the peripheral pixels EB and EC are acquired. Hereinafter, the region of the measurement target S corresponding to the target pixel is referred to as a target region, and the region of the measurement target S corresponding to the peripheral pixel is referred to as a peripheral region.

  As in the example of FIG. 10, when the measurement light L1 reflected from the peripheral region is incident on the target pixel as stray light, the measurement L1 reflected from the peripheral region is mainly incident on the peripheral pixel. For this reason, when the height data corresponding to the target pixel is erroneously generated, a certain tendency occurs in the relationship between the target pixel and the peripheral pixels. Therefore, in this example, based on the maximum received light amount of the target pixel EA, the height data corresponding to the target pixel EA, the maximum received light amount of the peripheral pixels EB and EC, and the height data corresponding to the peripheral pixels EB and EC, It is determined whether or not the height data corresponding to the target pixel EA has been generated based on stray light.

  Further, as in the example of FIG. 10, the height data generated based on stray light is likely to indicate the height of the surrounding area. Therefore, when the height data corresponding to the target pixel is generated based on stray light, it is highly likely that the height data corresponding to the target pixel matches or approximates the height data corresponding to the surrounding pixels.

  Further, when the reflectance of the peripheral region is high, there is a high possibility that the measurement light L1 reflected by the peripheral region enters the target pixel as stray light. Therefore, when the height data corresponding to the target pixel is generated based on stray light, there is a high possibility that the maximum received light amount of the peripheral pixels is large.

  As described above, there is a certain tendency in the degree of coincidence between the height data corresponding to the target pixel and the height data corresponding to the peripheral pixels, and the maximum amount of light received by the peripheral pixels. Therefore, the height data corresponding to the target pixel is based on stray light based on the relationship between the degree of coincidence between the height data corresponding to the target pixel and the height data corresponding to the peripheral pixel and the maximum received light amount of the peripheral pixel. It is preferable to determine whether or not it has been generated.

  For example, a determination formula including the degree of coincidence between the height data corresponding to the target pixel and the height data corresponding to the peripheral pixels and the maximum received light amount of the peripheral pixels is set in advance, and based on the value obtained by the determination formula Then, it is determined whether or not the height data corresponding to the target pixel is generated based on the stray light. The determination formula is not limited to a specific formula, and can be arbitrarily set in consideration of the above tendency. Further, an algorithm or the like for performing stray light determination may be separately used based on the above tendency.

  The height image data is corrected based on the result of the stray light determination. Specifically, height data determined to be generated based on stray light (hereinafter referred to as erroneously generated height data) is converted into invalid data. In the height image, a portion corresponding to invalid data is represented as a blank, for example. Further, in the measurement process, it is not possible to acquire a measurement value at a location corresponding to invalid data. This prevents an erroneous measurement value from being calculated based on the erroneously generated height data.

  The erroneously generated height data may be converted into height data indicating a predetermined minimum value or maximum value instead of being converted into invalid data. In this case, the user can surely recognize that the height data of the corresponding part is not properly generated. Further, as in the example of FIG. 11, when the envelope of the light reception amount includes a plurality of peaks, the height data may be generated again based on the peak indicating the second or less light reception amount.

(7) Filter level The user can adjust the filter level indicating the criteria for stray light determination. FIG. 13 is a diagram illustrating an example of a filter level adjustment screen displayed on the display unit 240 of FIG. The filter level adjustment screen SG of FIG. 13 includes an operation element OE. The user can adjust the level of the filter level by operating the operation unit 230 shown in FIG. The adjusted filter level is stored in the storage unit 220 in FIG. The stray light determination is performed based on the stored filter level. When the filter level is adjusted to be high, the ratio at which it is determined that the height data is generated based on stray light becomes relatively large. On the other hand, when the filter level is adjusted to be low, the rate at which the height data is determined to be generated based on stray light is relatively small.

  The user adjusts the filter level according to the shape of the surface of the measuring object S and the reflectance. Thereby, stray light determination is appropriately performed, and erroneously generated height data is appropriately detected from the height image data.

(8) Functional Configuration FIG. 14 is a functional block diagram showing functions realized by the control board 160 and the control unit 210. As shown in FIG. 14, the control board 160 includes a distance image generation unit 21 and a determination unit 22. The distance image generation unit 21 generates distance information of a region corresponding to each pixel of the light receiving unit 2 based on the measurement light received by the light receiving unit 2, and distance image data including distance information corresponding to a plurality of pixels Is generated. Specifically, the distance image generation unit 21 obtains distance information corresponding to each pixel based on the relative position of the movable unit 141 with respect to the support unit 125 detected by the position detection unit 14 and the amount of light received by the light receiving unit 2. Generate. The distance information indicates a distance between a predetermined position (for example, a light receiving position) of the shape measuring apparatus 300 and the surface of the measuring object S. In this example, height data corresponds to distance information, and height image data corresponds to distance image data.

  The determination unit 22 performs stray light determination for each pixel of the light receiving unit 2. Specifically, the determination unit 22 corresponds to the target pixel based on the maximum light reception amount of the target pixel, the height data corresponding to the target pixel, the maximum light reception amount of the peripheral pixels, and the height information corresponding to the peripheral pixels. It is determined whether the height data is calculated based on stray light.

  The control unit 210 includes a determination criterion receiving unit 23 and a calculation unit 24. The determination criterion receiving unit 23 receives adjustment of the determination criterion. In this example, the filter level corresponds to the determination criterion. The calculation unit 24 calculates a measurement value related to the shape of the measurement object S based on the height data determined not to be generated based on stray light by the determination unit 22. On the other hand, the calculation unit 24 does not calculate the measurement value based on the height data determined to be generated based on the stray light by the determination unit 22.

  These functional units may be realized by the CPU executing a program stored in the ROM or the like, or may be realized by hardware such as an electronic circuit.

  FIG. 15 is a flowchart illustrating an example of the operation of the CPU 160 a of the control board 160. In the example of FIG. 15, after height image data is generated, stray light determination for each pixel is performed based on the height image data. As illustrated in FIG. 15, the CPU 160a generates height data corresponding to each pixel based on the relative position detected by the position detection unit 14 and the amount of light received by the light receiving unit 2, and generates height image data. (Step S1). Next, CPU160a acquires the filter level memorize | stored in the memory | storage part 220 (step S2). Next, the CPU 160a selects a target pixel from among the plurality of pixels of the light receiving unit 2 (step S3). Next, the CPU 160a acquires the maximum amount of light received by the target pixel (step S4). Next, the CPU 160a acquires height data corresponding to the target pixel from the height image data generated in step S1 (step S5).

  Next, the CPU 160a identifies one peripheral pixel among the plurality of peripheral pixels (step S6). Next, the CPU 160a acquires the maximum received light amount of the specified peripheral pixels (step S7). Next, the CPU 160a acquires height data corresponding to the specified peripheral pixels from the height image data generated in step S1 (step S8). Next, the CPU 160a determines whether or not the maximum received light amount and height data have been acquired for all peripheral pixels. When not acquiring about all the surrounding pixels, CPU160a returns to step S6, and acquires the largest received light amount and height data about another surrounding pixel.

  When the maximum received light amount and height data are acquired for all the peripheral pixels, the CPU 160a performs stray light determination on the target pixel selected in step S3 (step S10). Specifically, it is determined whether or not the height data corresponding to the target pixel is generated based on stray light. Subsequently, the CPU 160a determines whether or not stray light determination has been completed for all pixels. If not completed for all the pixels, the CPU 160a returns to step S3 and performs the same processing for the other pixels. When the stray light determination is completed for all the pixels, the CPU 160a ends the process.

(9) Effects of the present embodiment In the shape measuring apparatus 300 according to the present embodiment, the relative position of the movable unit 141 with respect to the support unit 125 detected by the position detection unit 14 and the amount of light received by each pixel of the light receiving unit 2. Based on the above, the height data of the region of the measuring object S corresponding to each pixel of the light receiving unit 2 is obtained. In this case, since the plurality of pixels of the light receiving unit 2 are two-dimensionally arranged, height data of a wide area can be acquired simultaneously. Therefore, the height image data of the measuring object S can be generated at high speed and continuously.

  Further, stray light determination is performed for each pixel of the light receiving unit 2. In this case, based on the light reception amount of one pixel, distance information corresponding to one pixel, each light reception amount of one or more pixels around the one pixel, and one or more distance information corresponding to one or more pixels. Thus, it is determined whether or not the distance information corresponding to one pixel is generated based on the stray light. Such a determination is performed for all pixels. Thereby, the reliability of the height data corresponding to each pixel can be determined. Therefore, the reliability of the height image data can be improved.

(10) Other Embodiments In the above embodiment, height data is generated as distance information, but distance information indicating other dimensions may be generated. For example, by changing the relative position of each component of the shape measuring apparatus 300 with respect to the measurement object S, distance information indicating the dimensions of the measurement object in other directions can be generated. Further, distance image data including distance information corresponding to a plurality of pixels can be generated instead of the height image data.

  In the above embodiment, the distance information (height data) is generated by the interferometry, but the distance information may be generated by another method such as a TOF (Time Of Flight) method.

  In the above embodiment, the measurement unit 130 is configured such that the optical path length of the measurement light L1 changes and the optical path length of the reference light L2 does not change, but the present invention is not limited to this. The measurement unit 130 may be configured such that the optical path length of the reference light L2 changes and the optical path length of the measurement light L1 does not change. In this case, the mirror 10 is configured to vibrate relative to the beam splitter 12 along the traveling direction of the reference light L2.

(11) Correspondence between each component of claim and each part of embodiment The following describes an example of a correspondence between each component of the claim and each part of the embodiment. It is not limited.

  In the above embodiment, the measuring object S is an example of the measuring object, the shape measuring device 300 is an example of the shape measuring device, the light projecting unit 1 is an example of the light projecting unit, and the light receiving unit 2 is It is an example of a light receiving unit, the measurement light L1 is an example of measurement light, and the beam splitter 12 is an example of an optical system.

  The distance image generation unit 21 is an example of a distance image generation unit, the determination unit 22 is an example of a determination unit, the determination criterion reception unit 23 is an example of a determination criterion reception unit, and the calculation unit 24 is a calculation unit. It is an example. Further, the mirror 10 is an example of a reference body, the movable part 141 is an example of a movable part, the support part 125 is an example of a support part, the position detection part 14 is an example of a position detection part, and the reference light L2 Is an example of reference light, and interference light L3 is an example of interference light.

  As each constituent element in the claims, various other elements having configurations or functions described in the claims can be used.

  The present invention can be effectively used for measuring the shape of a measurement object.

DESCRIPTION OF SYMBOLS 1 Light projection part 2,3 Light reception part 21 Distance image generation part 22 Judgment part 23 Judgment reference reception part 24 Calculation part 100 Measurement head 110 Support structure 120 Case part 130 Measurement part 140 Reciprocation mechanism 150 Drive part 160 Control board 160a CPU
170 Communication Unit 200 Processing Device 210 Control Unit 220 Storage Unit 230 Operation Unit 240 Display Unit 250 Communication Unit 300 Shape Measuring Device

Claims (5)

A shape measuring device for measuring the surface shape of a measurement object,
A light projecting unit that emits light;
A light receiving unit including a plurality of pixels arranged two-dimensionally;
An optical system that guides the light emitted by the light projecting unit to the measurement object as measurement light, and guides the measurement light reflected by the measurement object to the light receiving unit;
Distance for generating distance image data including distance information corresponding to a plurality of generated pixels by generating distance information of a corresponding region of the measurement object for each pixel based on measurement light received by the light receiving unit Image generating means;
The amount of light received by one pixel of the light receiving unit, distance information corresponding to the one pixel, the amount of light received by one or more pixels around the one pixel, and one or more corresponding to the one or more pixels A shape measuring apparatus comprising: a determination unit that determines whether distance information corresponding to the one pixel is generated based on stray light based on distance information. A judgment criterion receiving means for receiving the adjustment of the criterion;
The shape measurement according to claim 1, wherein the determination unit determines whether distance information corresponding to the one pixel is generated based on stray light based on the determination criterion adjusted by the determination criterion reception unit. apparatus. The determination means is based on the degree of coincidence between the distance information corresponding to the one pixel and the one or more distance information corresponding to the one or more neighboring pixels, and the received light amount of each of the one or more neighboring pixels. The shape measuring apparatus according to claim 1, wherein distance information corresponding to the one pixel is determined based on stray light. The measurement information related to the shape of the measurement object is calculated based on distance information determined not to be generated based on stray light by the determination means, and the distance information determined to be generated based on stray light by the determination means The shape measuring apparatus according to claim 1, further comprising a calculation unit that does not calculate the measurement value based on the parameter. A reference body,
A movable part to which at least one of the optical system and the reference body is attached;
A support part for supporting the movable part so as to be reciprocally movable;
A position detection unit that detects a relative position of the movable unit with respect to the support unit;
The light projecting unit emits light having a plurality of peak wavelengths,
The optical system guides the light emitted from the light projecting unit to the reference body as reference light, and generates interference light between the measurement light reflected by the measurement object and the reference light reflected by the measurement object. Generating, guiding the generated interference light to the light receiving unit,
The movable part changes the difference between the optical path length of the measurement light and the optical path length of the reference light by reciprocating,
The said image generation means produces | generates the said distance image data based on the interference light received by the said light-receiving part, and the relative position detected by the said position detection part. Shape measuring device.

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