JP2012242134A - Shape measurement device and optical filter used for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable measurement of the shape of a large target object with high precision using a light-section method at a close distance, without increasing the size of device structure.SOLUTION: A shape measurement device 1 in one embodiment of this invention irradiates a target object 15 with slit light L1, images the slit light L1 reflected from the object 15 through a filter 3, and measures the shape of the object 15 while blocking light other than the slit light L1. A central transmission wavelength of the filter 3 is equivalent to a main peak wavelength of the slit light L1 in the vicinity of the optical axis C of a lens 4, and becomes larger along an incidence plane of the slit light L1 from the optical axis C toward an edge side of the filter 3.

Description

  The present invention relates to a shape measuring device that measures the shape of an object to be measured by a light cutting method and an optical filter used therefor.

  Conventionally, a light cutting method is known as a method for measuring the three-dimensional shape of an object to be measured. In the light cutting method, generally, the object to be measured is irradiated with high-luminance slit light such as laser light, and the surface shape such as irregularities of the object to be measured is measured based on the obtained slit light image.

  For example, in the light cutting method, as shown in FIG. 14, the slit light source 101 irradiates the surface of the measurement object 100 with slit light, and the imaging apparatus 102 measures the measurement object from a direction different from the irradiation direction of the slit light. The slit light reflected from 100 is imaged, and the obtained slit light image of the measured object 100 is displayed on the display device 103. The surface shape of the DUT 100 is calculated based on the deformation amount of the obtained slit light image, the geometric arrangement of the imaging optical system, and the like.

  Such a light cutting method has an advantage that a large object can be measured by a simple optical system, and the measurement sensitivity of the unevenness can be greatly adjusted by the arrangement of the optical system. For this reason, attention has been paid as a three-dimensional shape input method applied to a visual sensor for robots in accordance with recent advances in image processing technology.

  Also in the steel industry, the light cutting method is generated when manufacturing steel products such as steel pipes from the advantage that the shape in the direction along the slit light can be obtained while maintaining a high temperature state without cooling. It is applied to shape inspection of high-temperature intermediate products (see Patent Documents 1 to 3).

JP 2003-322513 A JP 2004-181471 A JP 2004-117053 A

  By the way, in the recent steel industry, not only steel products such as steel pipes, but also shape measurement by a light cutting method suitable for checking large and high-temperature equipment such as a coke oven is demanded. For example, there is a need for a shape measuring device that can measure the shape of a coke oven by an optical cutting method and inspect the unevenness of the inner wall surface of the coke oven. In the inspection of the coke oven, the shape measuring device must be brought close to the high temperature coke oven to measure the unevenness of the inner wall surface of the coke oven over a wide range.

  For this reason, it is necessary to enlarge the light projection range and light reception range of the shape measuring apparatus. Of these, for the light projection range, the slit light source of the shape measuring device may be changed to irradiate the slit light over a wider range, but this can be easily achieved by a method such as changing the slit length of the slit light source. it can.

  On the other hand, regarding the light receiving range, it is necessary to change the optical system of the shape measuring apparatus to increase the light receiving angle range, that is, the angle of view. In this case, the shape measuring apparatus receives the slit light reflected from the object to be measured over a range of incident angles larger than ever.

  Here, the shape measuring apparatus generally includes an optical filter such as an interference filter in order to receive the slit light reflected from the object to be measured with high sensitivity. However, the light transmission characteristics of the optical filter become lower as the incident angle of light increases.

  For this reason, when an optical filter having a light transmission characteristic limited to the wavelength of the slit light applied to the object to be measured is used, the optical filter is a slit light having a large incident angle, that is, a predetermined distance from the optical axis portion to the edge side. The slit light incident on the area more than the distance is blocked. As a result, since the slit light reflected from the object to be measured cannot be detected with high sensitivity, there is a problem that the shape of a large object to be measured cannot be accurately measured from a close distance by the light cutting method.

  The present invention has been made in view of the above circumstances, and a shape measuring device capable of accurately measuring the shape of a large object to be measured from a close distance by an optical cutting method without increasing the size of the device structure, and the same An object of the present invention is to provide an optical filter used in the above.

  In order to solve the above-described problems and achieve the object, a shape measuring apparatus according to the present invention irradiates a measurement object with slit light and reflects the reflected light of the slit light reflected from the measurement object through a lens. In the shape measuring apparatus that measures the shape of the object to be measured while shielding the light other than the reflected light, the transmission wavelength band near the optical axis of the lens includes the wavelength of the reflected light, and the reflected light An optical filter having a central transmission wavelength that increases from the optical axis toward the edge side along the incident surface is provided.

  In the shape measuring apparatus according to the present invention as set forth in the invention described above, the central transmission wavelength continuously increases from the optical axis toward the edge of the optical filter.

  In the shape measuring apparatus according to the present invention as set forth in the invention described above, the central transmission wavelength changes in accordance with a light receiving angle in a direction in which the target slit light extends long.

  In the shape measuring apparatus according to the present invention as set forth in the invention described above, the bandwidth of the transmission wavelength band of the optical filter is 2 to 4 times the half-value width of the slit light.

  In the shape measuring apparatus according to the present invention as set forth in the invention described above, the central transmission wavelength increases stepwise from the optical axis toward the edge of the optical filter.

  In the shape measuring apparatus according to the present invention as set forth in the invention described above, the optical filter includes a central region through which the optical axis passes and a plurality of partial regions that are symmetrically divided around the central region. The central transmission wavelength is equal to the main peak wavelength of the slit light in the central region, and increases for each partial region toward the edge of the optical filter.

  In the shape measuring apparatus according to the present invention as set forth in the invention described above, the transmission wavelength bands of the central region and the partial region overlap each other between the adjacent central region or the partial regions.

  In the shape measuring apparatus according to the present invention as set forth in the invention described above, the transmission wavelength bands of the central region and the partial region have the same bandwidth.

  In the shape measuring apparatus according to the present invention as set forth in the invention described above, the bandwidth of the transmission wavelength band of the partial region is wider than the bandwidth of the transmission wavelength band of the central region.

  In the shape measuring apparatus according to the present invention as set forth in the invention described above, the bandwidth of the transmission wavelength band of the partial region is a bandwidth obtained by multiplying the half width of the slit light by 2 to 4 times.

  An optical filter according to the present invention includes a lens that collects reflected light of slit light irradiated to a measurement object, and is an optical filter of a shape measurement apparatus that measures the shape of the measurement object by a light cutting method. The transmission wavelength band in the vicinity of the optical axis of the lens includes the wavelength of the reflected light, and includes a translucent film in which a central transmission wavelength increases from the optical axis toward the edge side along the incident surface of the reflected light. It is characterized by that.

  In the optical filter according to the present invention as set forth in the invention described above, the central transmission wavelength continuously increases from the optical axis toward the edge of the translucent film.

  In the optical filter according to the present invention as set forth in the invention described above, the central transmission wavelength changes in accordance with a light receiving angle in a direction in which the target slit light extends long.

  The optical filter according to the present invention is characterized in that, in the above invention, the bandwidth of the transmission wavelength band is 2 to 4 times the half-value width of the slit light.

  In the optical filter according to the present invention as set forth in the invention described above, the central transmission wavelength increases stepwise from the optical axis toward the edge of the translucent film.

  The optical filter according to the present invention is the optical filter according to the above invention, wherein the translucent film includes a central region through which the optical axis passes and a plurality of partial regions that are symmetrically divided around the central region. In addition, the central transmission wavelength is equal to the main peak wavelength of the slit light in the central region, and increases for each partial region toward the edge of the translucent film.

  In the optical filter according to the present invention as set forth in the invention described above, the transmission wavelength bands of the central region and the partial region overlap each other between the adjacent central region or the partial regions.

  In the optical filter according to the present invention as set forth in the invention described above, the transmission wavelength bands of the central region and the partial region have the same bandwidth.

  The optical filter according to the present invention is characterized in that, in the above invention, the transmission wavelength band of the partial region is wider than the transmission wavelength band of the central region.

  In the optical filter according to the present invention as set forth in the invention described above, the bandwidth of the transmission wavelength band of the partial region is a bandwidth that is 2 to 4 times the half-value width of the slit light.

  According to the shape measuring apparatus according to the present invention, it is possible to detect the slit light reflected from the object to be measured over a wider range of view angles with high sensitivity. Therefore, it is possible to accurately measure the shape of a large object to be measured.

  In addition, according to the optical filter of the present invention, it is possible to further widen the angle of view at which the slit light reflected from the object to be measured can be detected with high sensitivity. There is an effect that it is possible to realize a shape measuring apparatus capable of accurately measuring the shape of a large object to be measured from a close distance.

FIG. 1 is a block diagram schematically showing a configuration example of the shape measuring apparatus according to the first embodiment of the present invention. FIG. 2 is a schematic diagram illustrating a configuration example of the optical filter according to the first embodiment of the present invention. FIG. 3 is a schematic diagram illustrating light transmission characteristics of the optical filter according to the first embodiment. FIG. 4 is a schematic diagram illustrating a state in which slit light is incident near the optical axis of the filter. FIG. 5 is a schematic diagram showing a state in which slit light is incident near the edge of the filter. FIG. 6 is a diagram illustrating an example of the detection result of the slit light by the shape measuring apparatus from which the optical filter according to the first embodiment of the present invention is removed. FIG. 7 is a diagram illustrating a detection result of slit light when disturbance light is added to the state of FIG. FIG. 8 is a diagram illustrating an example of the detection result of the slit light by the shape measuring apparatus according to the first embodiment of the present invention. FIG. 9 is a diagram illustrating an example of a detection result of slit light by a conventional shape measuring apparatus. FIG. 10 is a diagram showing another example of the detection result of the slit light by the conventional shape measuring apparatus. FIG. 11 is a block diagram schematically illustrating a configuration example of the shape measuring apparatus according to the second embodiment of the present invention. FIG. 12 is a schematic diagram illustrating a configuration example of an optical filter according to the second embodiment of the present invention. FIG. 13 is a schematic diagram illustrating light transmission characteristics of the optical filter according to the second embodiment. FIG. 14 is a schematic diagram showing a conventional shape measuring apparatus using a light cutting method.

  Exemplary embodiments of a shape measuring apparatus according to the present invention and an optical filter used therewith will be described below in detail with reference to the accompanying drawings. In addition, this invention is not limited by this embodiment.

(Embodiment 1)
First, the configuration of the shape measuring apparatus according to the first embodiment of the present invention will be described. FIG. 1 is a block diagram schematically showing a configuration example of the shape measuring apparatus according to the first embodiment of the present invention. As shown in FIG. 1, the shape measuring apparatus 1 includes a slit light source 2 that irradiates a measurement object 15 with slit light L <b> 1, a filter 3 that transmits slit light L <b> 1 reflected from the measurement object 15, and a filter 3. A lens 4 that forms an image of the transmitted slit light L1 and an imaging unit 5 that images the slit light L1 imaged by the lens 4 are provided. In addition, the shape measuring apparatus 1 captures an image with the input unit 6 for switching the on / off state, the control unit 7 that controls the slit light source 2 and the imaging unit 5 in response to an input signal from the input unit 6, and the imaging unit 5. The image processing unit 8 that performs image processing of the slit light L1 that has been performed, the display unit 9 that displays the shape of the slit light L1 irradiated to the object 15 to be measured, and the case 10 for dust prevention and light shielding are provided. .

  The slit light source 2 irradiates substantially planar light over the measurement range of the measurement object 15. Specifically, the slit light source 2 is realized using a slit laser light source in which a semiconductor laser element and a lens are integrated, and irradiates the measurement surface 15a of the object 15 to be measured with slit light L1 having a predetermined wavelength band.

  The filter 3 is an optical filter that selectively transmits light necessary for measuring the shape of the object to be measured 15. Specifically, the filter 3 is realized using an interference filter or the like, and is fixedly disposed at the front stage (the object to be measured 15 side) of the lens 4 as shown in FIG. In this case, the filter 3 is disposed within the range of the angle of view defined by the lens 4. Further, the filter 3 is within the incident range of the reflected light of the slit light L1, that is, within the range of the broken line connecting the both ends of the slit light L1 on the measurement surface 15a shown in FIG. Be placed. The center axis of the surface of the filter 3 is preferably coincident with the optical axis C of the lens 4, but may be at least parallel to the optical axis C.

  The light transmission characteristics of the filter 3 transmit the reflected light of the slit light L1 and shield other light than this reflected light. From the optical axis C to the edge of the filter 3 along the incident surface of this reflected light. It changes with displacement.

  As shown in FIG. 1, the lens 4 is disposed between the filter 3 and the imaging unit 5, collects the reflected light of the slit light L1 selectively transmitted by the filter 3, and collects the reflected light. Is imaged on the light receiving surface of the imaging unit 5.

  The imaging unit 5 includes an imaging element 5a and captures a reflected light image of the slit light L1 formed by the lens 4. In this case, the image sensor 5a receives the reflected light imaged by the lens 4 and converts the intensity of the received reflected light into an electric signal corresponding to the pixel address. Thereafter, the imaging unit 5 transmits the electrical signal obtained by the imaging element 5 a to the image processing unit 8.

  The lens 4 and the imaging unit 5 described above may use known camera lenses and area sensor cameras, respectively, and the measurement range and resolution, that is, the number of vertical pixels and the number of horizontal pixels of the image sensor 5a on the object 15 to be measured. The selection should be made in consideration of the size of the area.

  The input unit 6 is realized by using an on / off switch or the like, and inputs a start instruction signal instructing measurement start or an end instruction signal instructing measurement end to the control unit 7 in response to an input operation of the operator. .

  The control unit 7 controls the operation timing of the slit light source 2 and the imaging unit 5 based on the instruction information input by the input unit 6. Specifically, when the start instruction signal is input, the control unit 7 controls the slit light source 2 so as to irradiate the slit light L1, and also captures a reflected light image of the slit light L1 and obtains the obtained image. The imaging unit 5 is controlled to sequentially transmit data to the image processing unit 8. On the other hand, when the end instruction signal is input, the control unit 7 controls the slit light source 2 to stop the irradiation operation of the slit light L1 and also controls the imaging unit 5 to stop the imaging operation.

  The image processing unit 8 performs predetermined image processing on the image data of the slit light L1 and measures the shape of the object 15 to be measured. Specifically, the image processing unit 8 acquires the image data converted into an electric signal by the imaging element 5a from the imaging unit 5, and converts the obtained image data into numerical data. Thereafter, the image processing unit 8 calculates the shape of the slit light L1 on the measurement surface 15a based on the numerical data, and calculates the shape of the unevenness of the measurement object 15 based on the calculation result. .

  The image processing unit 8 can be realized using a known image input circuit and image processing circuit, or can be easily realized by a combination of an image interface board and a personal computer. Moreover, the shape calculation process of the object 15 to be measured based on the shape calculation result of the slit light L1 described above can be realized by a combination of a known thinning process and an elementary calculation process, and further, a known shading may be performed as necessary. What is necessary is just to add the pre-processing which correct | amends the nonuniformity of the original image by correction | amendment.

  The display unit 9 acquires the image data of the slit light L1 and the shape measurement data of the measured object 15 from the image processing unit 8, and based on the obtained data, the reflected light image of the slit light L1 and the measured object 15 Displays the shape measurement result and the like.

  The housing 10 houses the slit light source 2, the filter 3, the lens 4, the imaging unit 5, and the control unit 7 described above. Here, in a manufacturing site such as a coke oven, high heat or dust is generated from steel products or equipment. On the other hand, the housing 10 ensures heat resistance (and cooling) and dustproofing of the internal components of the shape measuring device 1 when the shape measuring device 1 is used at the manufacturing site.

  Further, as shown in FIG. 1, an opening 10 a for irradiating the measurement object 15 with the slit light L <b> 1 is formed in the case 10 in the vicinity of the slit light source 2, and the slit reflected from the measurement object 15. An opening 10 b for entering the light L <b> 1 is formed in the vicinity of the filter 3.

  In addition, the transparent parts 11 and 12 are provided in the openings 10a and 10b, respectively. The translucent portions 11 and 12 are realized by a glass member or a resin member that is transparent to the wavelength band of the slit light L1. The translucent part 11 improves the internal dustproof property by the housing | casing 10, without inhibiting irradiation of the slit light L1. On the other hand, the translucent part 12 improves the internal dustproof property by the housing 10 without hindering the incidence of the slit light L1.

  Next, the configuration and light transmission characteristics of the filter 3 shown in FIG. 1 will be described in detail. FIG. 2 is a schematic diagram illustrating a configuration example of the optical filter according to the first embodiment of the present invention. FIG. 3 is a schematic diagram illustrating light transmission characteristics of the optical filter according to the first embodiment.

  As shown in FIG. 2, the filter 3 is formed by depositing a dielectric metal film 3b for generating light interference on one surface of a plate-like glass substrate 3a that is transparent to the wavelength band of the slit light L1. It is realized by forming by a manufacturing method.

  Here, for this filter 3, a two-axis orthogonal coordinate system orthogonal to the optical axis C of the lens 4 shown in FIG. 1 at the origin is set, and X of the X-axis and Y-axis of this orthogonal coordinate system is set. The axis is an axis parallel to the longitudinal direction of the slit light L1. In this case, the transmission wavelength band of the filter 3 in the vicinity of the optical axis C includes the wavelength of the reflected light of the slit light L1, and the central transmission wavelength of the filter 3 is filtered from the optical axis C along the incident surface of the reflected light. It becomes large toward the edge side of 3. That is, the center transmission wavelength of the filter 3 is equivalent to the main peak wavelength of the slit light L1 at the position of the optical axis C, and the edge side of the filter 3 from the optical axis C in both the positive and negative directions of the X axis shown in FIG. It becomes larger as it is displaced to.

Specifically, as shown in FIG. 3, the substantial central transmission wavelength λ of the filter 3 is symmetrical about the optical axis C on the light incident surface on the filter 3 and from the optical axis C to the edge side of the filter 3. As it is displaced, it continuously increases. In this case, the center transmission wavelength λ changes corresponding to the light receiving angle in the direction in which the target slit light L1 extends long. For example, the center transmission wavelength lambda, mainly the object side principal point 4a of the lens 4 described above, changes in an arc position X ₀ of the optical axis C as a vertex.

Specifically, the filter 3 has a center transmission wavelength λ ₀ equivalent to the main peak wavelength of the slit light L 1 at the position X ₀ of the optical axis C, and X ₁ from the optical axis C toward the edge of the filter 3. The center transmission wavelength λ continuously increases from λ ₀ to λ ₁ . Further, when the position X _{1 is} displaced from the position X ₁ toward the edge side of the filter 3 to X ₂ , the central transmission wavelength λ continuously increases from λ ₁ to λ ₂ .

Here, the incident angle θ of the slit light L1 reflected from the measured object 15 to the filter 3 increases along the X-axis direction of the light incident surface of the filter 3. That is, as shown by the dashed arrows in FIG. 3, the reflected light of the slit light L1 from the object to be measured 15, as the incident position is displaced towards the position X ₀ of the optical axis C in the edge of the filter 3, It is incident on the filter 3 more obliquely. Therefore, if the wavelength transmission characteristic is set so as to gradually increase from the center to the edge side of the filter 3 in a predetermined relationship, the substantial transmission characteristic of incident light can be made constant at both the center and the edge. .

  For this reason, the center transmission wavelength λ of the filter 3 is a function using the incident angle θ that changes with the displacement of the incident position in the X-axis direction as a variable, simply a function proportional to 1 / cos θ, or a simulation or It can be calculated based on a function derived by experiment or the like.

  Further, the transmission wavelength band of the filter 3 is preferably as narrow as possible from the viewpoint of transmitting the main wavelength component of the slit light L1 reflected from the DUT 15 and blocking unnecessary light components such as disturbance light. . Specifically, the transmission wavelength band of the filter 3 is set within a range of 2 to 4 times the half-value width of the main peak wavelength of the slit light L1, so that the transmission wavelength bands at each position on the light incident surface of the filter 3 overlap. It is desirable to set to.

  The filter 3 having the light transmission characteristics as described above is realized, for example, by adjusting or selecting the film thickness, the number of layers, the material, or the like of the dielectric metal film 3b attached to the surface of the glass substrate 3a.

  Since the incident angle θ in the Y-axis direction changes depending on the unevenness or distance of the DUT 15, the bandwidth of the transmission wavelength band of the filter 3 in the Y-axis direction varies with the transmission wavelength band characteristic due to this change in the incident angle. It is sufficient to set it to a level that absorbs. In this case, the center transmission wavelength λ of the filter 3 may be constant with respect to the displacement in the Y-axis direction, or may be increased from the optical axis C toward the edge of the filter 3 as in the X-axis direction. Alternatively, it may be set within a range of 2 to 4 times the half width of the main peak wavelength of the slit light L1.

  Next, the light transmission effect of the filter 3 will be described in detail. FIG. 4 is a schematic diagram illustrating a state in which slit light is incident near the optical axis of the filter. FIG. 5 is a schematic diagram showing a state in which slit light is incident near the edge of the filter.

  As shown in FIG. 4, when the slit light L1 reflected from the DUT 15 (see FIG. 1) enters the vicinity of the optical axis C of the filter 3, the incident angle θ of the slit light L1 with respect to the filter 3 is substantially zero. A close value. In this case, the film thickness d of the dielectric metal film 3b and the path length (d × cos θ) of the slit light L1 passing through the dielectric metal film 3b are almost equal to each other. For this reason, the slit light L1 is incident on the vicinity of the optical axis C of the filter 3, is transmitted through the intrinsic interference action of the dielectric metal film 3b having the film thickness d, and then passes through the glass substrate 3a.

  On the other hand, as shown in FIG. 5, when the slit light L <b> 1 is incident near the edge of the filter 3, the incident angle θ is larger than that when incident near the optical axis C described above. The path length (d × cos θ) of the slit light L1 in the dielectric metal film 3b is a value that cannot be ignored compared to the film thickness d of the dielectric metal film 3b. For this reason, the thickness of the dielectric metal film 3b through which the slit light L1 passes becomes equivalently large.

  Here, in the case of the conventional interference filter, when the path length of the dielectric metal film 3b, that is, the film thickness d increases as the incident angle θ of the slit light L1 increases, the slit light L1 As a result, the slit light L1 that should originally pass through does not pass through the interference filter. This is because the center transmission wavelength λ of the interference filter shifts to the short wavelength side as the incident angle θ of light increases.

  On the other hand, the filter 3 described above increases the central transmission wavelength λ from the optical axis C toward the edge of the filter 3 as shown in FIG. For this reason, even when the incident angle θ of the slit light L1 increases, the filter 3 always has a central transmission wavelength λ equivalent to the main peak wavelength of the slit light L1 at the incident position of the slit light L1. The transmission wavelength band of the filter 3 is set to be continuous on the incident surface of the slit light L1. As a result, the filter 3 can transmit the slit light L1 reflected from a wide range over the range of both ends of the measured object 15 with high sensitivity, and can block unnecessary light other than the slit light L1 such as disturbance light.

  Next, an example of the shape measuring apparatus 1 according to the first embodiment of the present invention will be shown, and the operation and effect of the first embodiment will be specifically described. FIG. 6 is a diagram illustrating an example of the detection result of the slit light by the shape measuring apparatus from which the optical filter according to the first embodiment of the present invention is removed. FIG. 7 is a diagram illustrating a detection result of slit light when disturbance light is added to the state of FIG. FIG. 8 is a diagram illustrating an example of the detection result of the slit light by the shape measuring apparatus according to the first embodiment of the present invention. FIG. 9 is a diagram illustrating an example of a detection result of slit light by a conventional shape measuring apparatus. FIG. 10 is a diagram showing another example of the detection result of the slit light by the conventional shape measuring apparatus.

  In the shape measuring apparatus 1 shown in FIG. 1, the filter 3 is fixedly disposed at a position 100 mm from the virtual center of the field angle of the lens 4. The angle of view of the lens 4 was set to an actual measurement value of 63 degrees. On the other hand, the main peak wavelength of the slit light L1 was 532 nm, and its half width was 3 nm.

  In accordance with the slit light L1, the center transmission wavelength λ of the filter 3 was set to 532 nm at the position of the optical axis C. The central transmission wavelength λ is continuously increased from the position of the optical axis C toward the edge of the filter 3, specifically, the position displaced by 30.1 mm from the optical axis C in the X-axis direction. And 625 nm at this edge. Furthermore, the transmission wavelength bandwidth of the filter 3 was set to 5 nm.

  First, as a comparative example, the filter 3 was removed from the shape measuring apparatus 1, and the slit light L1 was detected using a flat panel as an example of the object 15 to be measured. Specifically, a flat panel is disposed 1000 mm in front of the shape measuring apparatus 1, the slit light L 2 is irradiated to the flat panel by the slit light source 2, and the slit light L 1 reflected from the flat panel is passed through the filter 3. Images were taken without As a result, as shown in FIG. 6, slit light was detected across both ends of the flat panel.

  Next, the slit light L1 reflected from the flat panel and the disturbance light were imaged without passing through the filter 3 while further irradiating the flat panel with disturbance light from a broadband halogen lamp in the state described above. As a result, as shown in FIG. 7, the influence of disturbance light is severer than that of the slit light L1, and therefore, the slit light L1 cannot be distinguished from the disturbance light at the disturbance light irradiation position.

  On the other hand, the filter 3 was attached to the shape measuring apparatus 1, and the same flat panel was imaged in the state irradiated with the slit light L1 and the disturbance light. As a result, a slit light detection result as shown in FIG. 8 was obtained. That is, the filter 3 can clearly transmit the slit light L1 reflected from the flat panel over the entire area of the imaging field while blocking disturbance light that is unnecessary light.

  By providing this filter 3, the shape measuring apparatus 1 can detect the slit light L1 incident from a light receiving range with a wide angle of view with high sensitivity while excluding light unnecessary for shape measurement such as disturbance light. Such a shape measuring apparatus 1 can accurately measure the shape of an object to be measured at a high temperature and in a wide range such as an inner wall surface of a coke oven.

  When a conventional interference filter having the same central transmission wavelength at the position of the optical axis C is attached to the shape measuring apparatus 1 in place of the filter 3 described above, the detection result of the slit light L1 as shown in FIG. 9 is obtained. It was. In this case, disturbance light can be blocked by the conventional interference filter, but as shown in FIG. 9, the slit light L1 reflected from the vicinity of the center of the flat panel can be barely detected. On the other hand, the detection intensity of the slit light L1 reflected from the vicinity of the edge side of the flat panel is remarkably reduced, and as a result, it cannot be detected as shown in FIG.

  On the other hand, as another comparative example, instead of the filter 3 described above, an interference filter having a uniform transmission characteristic with a transmission wavelength band widened to 528 to 570 nm is attached to the shape measuring apparatus 1 in order to increase the S / N ratio. A similar slit light detection experiment was conducted. As a result, as shown in FIG. 10, the slit light L1 could be detected, but disturbance light was detected at the same time, and the shape measurement accuracy was insufficient.

  As described above, in the first embodiment of the present invention, the central transmission wavelength λ is continuous from the optical axis C toward the edge of the filter 3 along the incident surface of the slit light L1 reflected from the object 15 to be measured. It is large in size. For this reason, even if the transmission wavelength band of the filter 3 is shifted from the original wavelength band suitable for the slit light L1 to the low wavelength side as the incident angle θ of the slit light L1 with respect to the filter 3 increases, the slit The center transmission wavelength λ of the filter 3 is always equal to the main peak wavelength of the slit light L1 at the incident position of the light L1, and a transmission wavelength band suitable for the slit light L1 can be ensured regardless of the increase of the incident angle θ. As a result, the slit light L1 reflected from a wide range over the range of both ends of the object to be measured 15 can be transmitted with high sensitivity and unnecessary light other than the slit light L1 such as disturbance light can be blocked. The size of a large object to be measured, such as a coke oven, can be accurately measured from a close distance by an optical cutting method without increasing the size.

(Embodiment 2)
Next, a second embodiment of the present invention will be described. In the first embodiment described above, the center transmission wavelength λ is continuously increased from the optical axis C toward the edge of the filter 3, but in this second embodiment, the optical axis C is directed toward the filter edge. Thus, the central transmission wavelength λ is increased stepwise.

  FIG. 11 is a block diagram schematically illustrating a configuration example of the shape measuring apparatus according to the second embodiment of the present invention. As shown in FIG. 11, the shape measuring device 21 includes a filter 23 instead of the filter 3 of the shape measuring device 1 according to the first embodiment described above. Other configurations are the same as those of the first embodiment, and the same reference numerals are given to the same components.

  The filter 23 is an optical filter that selectively transmits light necessary for measuring the shape of the object 15 to be measured, and is fixedly disposed in front of the lens 4 in the same manner as the filter 3 according to the first embodiment. The filter 23 has different light transmission characteristics compared to the filter 3 according to the first embodiment.

  Next, the configuration and light transmission characteristics of the filter 23 will be described in detail. FIG. 12 is a schematic diagram illustrating a configuration example of an optical filter according to the second embodiment of the present invention. FIG. 13 is a schematic diagram illustrating light transmission characteristics of the optical filter according to the second embodiment.

  As shown in FIG. 12, the filter 23 includes dielectric metal films 23b, 23c-1, 23c-2, 23d-1, and the like for causing light interference on one surface of the glass substrate 3a by a method such as vapor deposition. This is realized by forming 23d-2, 23e-1, 23e-2, 23f-1, and 23f-2.

  Here, for this filter 23, a two-axis orthogonal coordinate system orthogonal to the optical axis C of the lens 4 shown in FIG. 11 at the origin is set, and X of the X-axis and Y-axis of this orthogonal coordinate system is set. The axis is an axis parallel to the longitudinal direction of the slit light L1. In this case, as shown in FIG. 12, the dielectric metal film 23b is located on the Y axis. Further, dielectric metal films 23c-1, 23d-1, 23e-1, and 23f-1 are respectively formed in the positive direction of the X axis with the dielectric metal film 23b as a center, and the negative X axis is formed. Dielectric metal films 23c-2, 23d-2, 23e-2, and 23f-2 are formed in the direction of.

  Thus, the dielectric metal films 23b, 23c-1, 23c-2, 23d-1, 23d-2, 23e-1, 23e-2, 23f-1, 23f-2 formed on the glass substrate 3a are as follows: Each is perpendicular to the X-axis direction, and forms a dielectric metal film group in which the central transmission wavelength λ increases stepwise from the optical axis C toward the edge of the filter 23 as shown in FIG.

Specifically, the dielectric metal film 23b is formed in a central region H1 having the optical axis C as a central axis among a plurality of regions obtained by dividing the glass substrate 3a, and has a central transmission equivalent to the main peak wavelength of the slit light L1. having a wavelength λ _10.

Further, the dielectric metal films 23c-2, 23d-2, 23e-2, 23f-2, 23c-1, 23d-1, 23e-1, and 23f-1 are symmetrically divided around the central region H1. Formed in the plurality of partial regions H2 to H9. The dielectric metal films 23c-2 and 23c-1 have a central transmission wavelength λ ₁₁ that is larger than the central transmission wavelength λ ₁₀ of the dielectric metal film 23b. The dielectric metal films 23d-2 and 23d-1 The central transmission wavelength λ ₁₂ is larger than the central transmission wavelength λ ₁₁ . The dielectric metal film 23e-2,23e-1 has a central transmission wavelength lambda ₁₃ larger than this central transmission wavelength lambda _12, dielectric metal film 23f-2,23f-1, the center The center transmission wavelength λ ₁₄ is larger than the transmission wavelength λ ₁₃ .

  On the other hand, the transmission wavelength bands of the dielectric metal films 23b, 23c-1, 23c-2, 23d-1, 23d-2, 23e-1, 23e-2, 23f-1, and 23f-2 are adjacent to the central region. It is set to overlap between H1 or partial regions H2 to H9. In this case, the bandwidths of the central region H1 and the partial regions H2 to H9 are set so that the main peak wavelength of the slit light L1 is included in the transmission wavelength band of these regions, as shown in FIG. . The main peak wavelength of the slit light L1 changes in an arc shape around the object side principal point 4a as shown by the broken line in FIG.

  Specifically, the transmission wavelength band of the dielectric metal film 23b overlaps with the transmission wavelength bands of the adjacent dielectric metal films 23c-1 and 23c-2. The transmission wavelength band of the dielectric metal film 23c-1 overlaps the transmission wavelength band of the adjacent dielectric metal film 23d-1, and the transmission wavelength band of the dielectric metal film 23d-1 is the adjacent dielectric metal film. The transmission wavelength band of the dielectric metal film 23e-1 overlaps the transmission wavelength band of the adjacent dielectric metal film 23f-1. Similarly, the transmission wavelength band of the dielectric metal film 23c-2 overlaps the transmission wavelength band of the adjacent dielectric metal film 23d-2, and the transmission wavelength band of the dielectric metal film 23d-2 is equal to the adjacent dielectric metal film. It overlaps with the transmission wavelength band of the film 23e-2, and the transmission wavelength band of the dielectric metal film 23e-2 overlaps with the transmission wavelength band of the adjacent dielectric metal film 23f-2.

  Moreover, the bandwidth of each transmission wavelength band of the dielectric metal films 23b, 23c-1, 23c-2, 23d-1, 23d-2, 23e-1, 23e-2, 23f-1, and 23f-2 described above is as follows. Are set to the same bandwidth.

The above-described central transmission wavelengths λ _{10 to} λ ₁₄ of each region are derived by simulation or experiment or the like using a function with the incident angle θ of the slit light L1 that changes with the displacement of the incident position in the X-axis direction as a variable. And can be calculated based on the obtained function.

  The filter 23 having the light transmission characteristics as described above includes, for example, dielectric metal films 23b, 23c-1, 23c-2, 23d-1, 23d-2, 23e-1, 23e-2, 23f-1, and 23f. -2 film thickness, number of layers, material, etc. are adjusted or selected.

Note that the center transmission wavelengths λ _{10 to} λ ₁₄ of the filter 23 may be constant with respect to the displacement in the Y-axis direction shown in FIG. 12, or from the optical axis C to the filter as in the X-axis direction. You may enlarge toward 3 edge side. In addition, since the incident angle θ in the Y-axis direction changes depending on the unevenness or distance of the DUT 15, the bandwidth of the transmission wavelength band of the filter 23 in the Y-axis direction varies in the transmission wavelength band characteristic due to the change in the incident angle. It is sufficient to set it to a level that absorbs.

  The filter 23 having the light transmission characteristics as described above exhibits the same light transmission effect as the filter 3 according to the first embodiment. For this reason, the filter 23 can transmit the slit light L1 reflected from a wide range over the range of both ends of the DUT 15 with high sensitivity and can block unnecessary light other than the slit light L1 such as disturbance light.

  As described above, in the second embodiment of the present invention, the filter 23 is divided into a plurality of regions along the longitudinal direction of the slit light L1 reflected from the object to be measured 15, and the transmission wavelength band between adjacent regions is obtained. The central transmission wavelengths of the plurality of regions are gradually increased from the optical axis C toward the edge of the filter 23. For this reason, since the center transmission wavelength can be continuously increased approximately from the optical axis C toward the edge of the filter 23, the same effect as in the case of the first embodiment described above can be enjoyed, and from the optical axis C. A filter having a larger central transmission wavelength toward the filter edge can be easily realized.

  In the first and second embodiments described above, the center transmission wavelengths of the filters 3 and 23 are changed in a direction parallel to the longitudinal direction of the slit light L1, but the present invention is not limited to this, and the incidence of the slit light L1 is performed. If the center transmission wavelength includes the main peak wavelength of the slit light L1 on the surface and increases with an increase in the incident angle θ, the central transmission wavelengths of the filters 3 and 23 in a direction oblique to the longitudinal direction of the slit light L1 May be changed.

  In the first and second embodiments described above, the filter in which the dielectric metal film is formed on the surface of the glass substrate is used. However, the present invention is not limited to this, and the slit light L1 such as a resin substrate is used instead of the glass substrate. It may be a filter in which a dielectric metal film is formed on the surface of a transparent transparent member.

  Furthermore, in the first and second embodiments described above, the filter in which the dielectric metal film is formed on the surface of the glass substrate is used. However, the present invention is not limited to this, and the dielectric film is replaced with a glass substrate or the like. It may be a filter formed on the surface of the translucent member.

  In the first and second embodiments described above, the center transmission wavelength of the filters 3 and 23 is changed around the object-side principal point 4a of the lens 4. However, the present invention is not limited to this. You may change the center transmission wavelength of the filters 3 and 23 centering on an image side principal point.

  Furthermore, in Embodiments 1 and 2 described above, a slit laser light source in which a semiconductor laser element and a lens are integrated is used as the slit light source 2, but the present invention is not limited to this, and as shown in FIG. It may be a slit light source that irradiates light from a slit plate through a slit plate, or may be a scanning light source that scans spot light emitted from a point light source in a fan-like or parallel manner at high speed by an optical member such as a vibrating mirror Good.

  In the first and second embodiments described above, the shape measuring device operated using the input unit 6 is exemplified. However, the present invention is not limited to this, and the slit light source 2 is not provided without providing the input unit 6 and the control unit 7 described above. The imaging unit 5 may be provided with an on / off switch, and each switch may be operated.

  Further, in the second embodiment described above, the filter having the dielectric metal film divided into the central region H1 and the eight partial regions H2 to H9 sandwiching the central region H1 is illustrated. However, the partial regions provided on both sides of the central region H1 are illustrated. The number is not limited to eight, but may be two or more.

  In the second embodiment described above, the bandwidths of the transmission wavelength bands of the center region H1 and the partial regions H2 to H9 of the filter 23 are the same. However, the present invention is not limited to this, and the transmission wavelength band of the center region H1. And the bandwidth of the transmission wavelength band of the partial regions H2 to H9 may be wider than that of the central region H1. In this case, the bandwidth of the partial regions H2 to H9 may be set to 2 to 4 times the half width of the main peak wavelength of the slit light L1.

DESCRIPTION OF SYMBOLS 1,21 Shape measuring apparatus 2 Slit light source 3, 23 Filter 3a Glass substrate 3b, 23b, 23c-1-23f-1, 23c-2-23f-2 Dielectric metal film 4 Lens 4a Object side principal point 5 Imaging part 5a Image sensor 6 Input unit 7 Control unit 8 Image processing unit 9 Display unit 10 Case 10a, 10b Opening 11, 12 Translucent unit 15 Object 15a Measurement surface 100 Object 101 Slit light source 102 Imaging device 103 Display device C Optical axis H1 Central region H2 to H9 Partial region L1 Slit light

Claims (20)

A shape for measuring the shape of the object to be measured by irradiating the object to be measured with slit light, imaging the reflected light of the slit light reflected from the object to be measured through a lens, and shielding light other than the reflected light In the measuring device,
A transmission wavelength band in the vicinity of the optical axis of the lens includes the wavelength of the reflected light, and includes an optical filter in which a central transmission wavelength increases from the optical axis toward the edge side along the incident surface of the reflected light. A shape measuring device.   The shape measuring apparatus according to claim 1, wherein the central transmission wavelength continuously increases from the optical axis toward an edge side of the optical filter.   The shape measuring apparatus according to claim 2, wherein the central transmission wavelength changes corresponding to a light receiving angle in a direction in which the target slit light extends long.   The shape measuring apparatus according to claim 1, wherein a bandwidth of a transmission wavelength band of the optical filter is 2 to 4 times a half-value width of the slit light.   The shape measuring apparatus according to claim 1, wherein the central transmission wavelength increases stepwise from the optical axis toward an edge side of the optical filter. The optical filter includes a central region through which the optical axis passes, and a plurality of partial regions that are symmetrically divided around the central region,
The shape measurement according to claim 5, wherein the central transmission wavelength is equal to a main peak wavelength of the slit light in the central region, and increases for each partial region toward an edge side of the optical filter. apparatus.   The shape measuring apparatus according to claim 6, wherein the transmission wavelength bands of the central region and the partial region overlap each other between the adjacent central region or the partial regions.   The shape measuring apparatus according to claim 6 or 7, wherein bandwidths of transmission wavelength bands of the central region and the partial region are the same.   The shape measuring apparatus according to claim 6 or 7, wherein a bandwidth of the transmission wavelength band of the partial region is wider than a bandwidth of the transmission wavelength band of the central region.   The shape measuring apparatus according to claim 9, wherein a bandwidth of a transmission wavelength band of the partial region is a bandwidth obtained by multiplying a half width of the slit light by 2 to 4 times. In the optical filter of the shape measuring apparatus, which has a lens for collecting the reflected light of the slit light irradiated to the object to be measured, and measures the shape of the object to be measured by a light cutting method,
A transmission wavelength band in the vicinity of the optical axis of the lens includes the wavelength of the reflected light, and a translucent film having a central transmission wavelength that increases from the optical axis toward the edge side along the incident surface of the reflected light is provided. An optical filter characterized by.   The optical filter according to claim 11, wherein the central transmission wavelength continuously increases from the optical axis toward an edge side of the translucent film.   The optical filter according to claim 12, wherein the central transmission wavelength changes corresponding to a light receiving angle in a direction in which the target slit light extends long.   14. The optical filter according to claim 11, wherein a bandwidth of a transmission wavelength band is 2 to 4 times a half-value width of the slit light.   The optical filter according to claim 11, wherein the central transmission wavelength increases stepwise from the optical axis toward the edge of the translucent film. The translucent film includes a central region through which the optical axis passes, and a plurality of partial regions that are symmetrically divided around the central region,
The central transmission wavelength is equal to the main peak wavelength of the slit light in the central region, and increases for each partial region toward the edge of the translucent film. Optical filter.   The optical filter according to claim 16, wherein the transmission wavelength bands of the central region and the partial region overlap each other between the adjacent central region or the partial regions.   The optical filter according to claim 16 or 17, wherein bandwidths of transmission wavelength bands of the central region and the partial region are the same.   The optical filter according to claim 16 or 17, wherein a bandwidth of a transmission wavelength band of the partial region is wider than a bandwidth of a transmission wavelength band of the central region.   The optical filter according to claim 19, wherein the bandwidth of the transmission wavelength band of the partial region is a bandwidth obtained by multiplying the half-value width of the slit light by 2 to 4 times.