Optical displacement gauge

Abstract

To suppress deterioration of intrusion prevention performance of disturbance light because of a change in a relative angle between a light projection system and a light reception window.SOLUTION: An optical displacement gauge includes: a light projection / reception module having a light projection section for applying slit beams extending in the X direction, a light receiving lens for condensing reflection light obtained by reflection of slit beams by a workpiece, a bandpass filter in which a relative position to the light receiving lens is fixed, and an imaging section for receiving light condensed by the light receiving lens; a motor for integrally rotating the light projection / reception module; a housing for storing the light projection / reception module and providing a light reception window for transmitting the reflection light; and a control section for controlling the motor and performing scanning of slit beams in a direction orthogonal to the X direction. Regardless of a rotational angle of the light projection / reception module during a measuring operation, the light reception window transmits light in a predetermined wavelength range including a wavelength range of slit beams, and the bandpass filter selectively passes or reflects reflection light of slit beams from among light transmitted through the light reception window and allows it to impinge on the imaging section.SELECTED DRAWING: Figure 11

Description

[Technical field]

[0001] The present invention relates to an optical displacement meter. [Background technology]

[0002] When acquiring two-dimensional profiles of the XZ cross section at different positions in the Y direction of the measurement target (workpiece) using a conventional optical displacement meter and generating three-dimensional shape data from these two-dimensional profiles, the conventional optical displacement meter must move in the Y direction relative to the workpiece. This requires equipment such as a conveyor for transporting the workpiece and a linear motion mechanism for moving the conventional optical displacement meter body relative to the workpiece. However, the introduction of the above-mentioned equipment can be hindered by installation space, costs, etc.

[0003] On the other hand, an optical displacement meter that rotates a light projection system and a light receiving system is known as an optical displacement meter that does not require the above-mentioned equipment, can acquire two-dimensional profiles of the XZ cross section at different positions in the Y direction of the workpiece, and can generate three-dimensional shape data from these two-dimensional profiles (see Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] European Patent Application Publication No. 3232152 [Patent Document 2] China Utility Model No. 210664364 Summary of the Invention [Problem to be solved by the invention]

[0005] In an optical displacement meter, the light projection system and the light receiving system are stored in a housing, and the housing is provided with a light projection window and a light receiving window to prevent dust from adhering to the light projection system and the light receiving system. A bandpass filter may be formed in the light receiving window to prevent the intrusion of disturbance light having a wavelength range different from the slit light irradiated from the optical displacement meter. For example, the relationship between the wavelength range and the transmittance of a bandpass filter made of an optical thin film filter changes depending on the angle of incidence of the incident light. Generally, when the angle of incidence to the bandpass filter increases from 0 degrees (vertical incidence), the wavelength range with high transmittance shifts to the short wavelength side.

[0006] In an optical displacement meter in which the angle between the optical axis of the light-receiving lens and the light-receiving window is fixed, the angle at which the light on that optical axis, i.e., the light that can be most focused by the light-receiving lens, enters the bandpass filter formed in the light-receiving window is also fixed, so the transmission characteristics of the bandpass filter for the light on that optical axis do not substantially change.

[0007] On the other hand, it has been found that the following problem exists in the optical displacement gauge in which the light-projecting system and the light-receiving system are rotated as in Patent Document 1 and Patent Document 2. That is, when the light-projecting system and the light-receiving system are rotated in a housing having a light-receiving window, the angle between the optical axis of the light-receiving lens and the light-receiving window changes, and therefore, if a band-pass filter is formed in the light-receiving window, the angle at which the light on the optical axis enters the band-pass filter also changes.

[0008] Of the slit light emitted from the projection system and reflected by the workpiece, the light that is focused by the receiving lens enters the bandpass filter centered on the optical axis of the receiving lens. Therefore, due to changes in the angle between the optical axis and the bandpass filter, the amount of reflected light of the slit light that passes through the bandpass filter decreases, and the measurement accuracy also decreases.

[0009] Although the use of a bandpass filter with high transmittance in a wider wavelength range can suppress a decrease in the amount of reflected light of the slit light passing through the bandpass filter, the measurement accuracy is inevitably reduced because the filter becomes susceptible to the effects of ambient light. Patent Documents 1 and 2 do not mention the housing or the light receiving window, and do not take any measures to address the above problems.

[0010] In view of the above problems, the present invention aims to provide an optical displacement meter that can suppress the effects of external light while preventing a decrease in the amount of reflected light of the slit light received, even when the light-projecting system and the light-receiving system are rotated. [Means for solving the problem]

[0011] An optical displacement meter according to one aspect of the present invention includes, for example, a light projecting and receiving module having a light projecting unit that irradiates a slit light extending in the X direction, a light receiving lens that collects reflected light of the slit light reflected by a workpiece, a bandpass filter whose relative position with the light receiving lens is fixed, and an imaging unit that receives the light collected by the light receiving lens, a motor that rotates the light projecting and receiving module as a unit, a housing that stores the light projecting and receiving module and has a light receiving window that transmits the reflected light, and a control unit that controls the motor and scans the slit light in a direction perpendicular to the X direction, wherein the light receiving window transmits light of a predetermined wavelength range that includes the wavelength range of the slit light regardless of the rotation angle of the light projecting and receiving module during measurement operation, and the bandpass filter selectively passes or reflects the reflected light of the slit light from the light that has transmitted through the light receiving window, and causes it to be incident on the imaging unit.

[0012] An optical displacement meter according to another aspect of the present invention includes, for example, a light projecting and receiving module having a light projecting unit that irradiates slit light extending in an X direction, a light receiving lens that collects reflected light of the slit light reflected by a workpiece, and an imaging unit that receives the light collected by the light receiving lens; a motor that rotates the light projecting and receiving module as a unit; a housing that stores the light projecting and receiving module and has a light receiving window that transmits the reflected light; and a control unit that controls the motor and scans the slit light in a direction perpendicular to the X direction, wherein the light receiving window has a substantially constant transmittance in a predetermined wavelength range that includes the wavelength range of the slit light, regardless of changes in the angle of incidence, and is formed of a colored glass filter that has a higher transmittance in the wavelength range of the slit light than the transmittance of the slit light outside the wavelength range and within the predetermined wavelength range, and regardless of the rotation angle of the light projecting and receiving module during measurement operation, the colored glass filter selectively passes the reflected light of the slit light to be incident on the imaging unit.

[0013] However, other features, elements, steps, advantages, and characteristics will become more apparent from the detailed description that follows and the accompanying drawings related thereto. Effect of the Invention

[0014] According to one aspect of the present invention, the angle range at which the reflected light of the slit light is incident on the light receiving window is wider than in a conventional non-rotating optical displacement meter, so that the light receiving window transmits light in a wider wavelength range than the slit light regardless of the incident angle, and by providing a bandpass filter whose relative position with respect to the light receiving lens is fixed, it is possible to suppress a decrease in the amount of reflected light of the slit light collected by the light receiving lens that passes through the bandpass filter regardless of rotation, while also suppressing the effects of disturbance light. According to another aspect of the present invention, by using a colored glass filter for the light receiving window, which has a characteristic that the transmittance is approximately constant regardless of changes in the incident angle in a predetermined wavelength range including the wavelength range of the slit light, it is possible to suppress a decrease in the amount of received reflected light of the slit light due to rotation of the light emitting and receiving module during measurement operation, while also suppressing the effects of disturbance light. [Brief description of the drawings]

[0015] [Figure 1] Diagram explaining the optical displacement measurement system [Diagram 2] Diagram explaining the principle of triangulation [Diagram 3] FIG. 1 is a diagram illustrating an optical displacement meter having a reflecting member. [Figure 4] A diagram explaining a method for detecting peak positions [Diagram 5] Functional block diagram of optical displacement sensor [Figure 6] FIG. 1 is a diagram illustrating a first example of a motor arrangement. [Figure 7] FIG. 1 is a diagram illustrating a first example of a motor arrangement. [Figure 8] FIG. 2 is a diagram illustrating a second example of motor arrangement. [Figure 9] FIG. 2 is a diagram illustrating a second example of motor arrangement. [Figure 10] FIG. 1 is a diagram showing a process flow of the measurement operation of the optical displacement measurement system. [Figure 11] FIG. 1 is a diagram illustrating a first example of the arrangement of band-pass filters; [Figure 12] FIG. 13 is a diagram for explaining a second example of the arrangement of band-pass filters; [Figure 13] FIG. 11 is a diagram illustrating a third example of the arrangement of bandpass filters. [Figure 14] FIG. 4 is a diagram for explaining a fourth example of the arrangement of band-pass filters; [Figure 15] FIG. 5 is a diagram for explaining a fifth example of the arrangement of bandpass filters. [Figure 16] FIG. 1 is a diagram for explaining the relationship between the wavelength range of slit light and the transmission characteristics of a bandpass filter and a light receiving window. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] <Optical displacement measurement system> 1 is a diagram showing a schematic configuration example of an optical displacement measurement system 100 of this configuration example, which includes an optical displacement meter 1, a control device 2, a display device 3, and an input device 4.

[0017] In this configuration example, the X direction corresponds to the width direction of the slit light L1 output from the optical displacement meter 1, the Z direction corresponds to the height direction of the workpiece W, and the Y direction corresponds to the direction in which the slit light L1 moves due to the rotation of the light projector (not shown in FIG. 1). The XZ plane described below is a plane extending in the X and Z directions. Since the optical displacement meter 1 scans the slit light L1 by rotating the light projector / receiver module 20, the scanning direction of the slit light L1 is a direction perpendicular to the X direction in the YZ plane, including the Y direction. In this specification, "rotation" refers to a swinging motion that reciprocates around a rotation axis.

[0018] The optical displacement measurement system 100 is a system that measures the profile and three-dimensional shape of the workpiece W. The profile of the workpiece W is data indicating the outer edge of the cut surface of the workpiece W by the slit light L1. When the slit light is irradiated parallel to the XZ plane, the profile of the workpiece W becomes data indicating the outer edge of the cut surface parallel to the XZ plane, and is therefore also called a two-dimensional profile of the XZ cross section of the workpiece W.

[0019] For example, a profile is a collection of (xi,zi) (i is the index). xi indicates the position in the X direction. zi indicates the height in the Z direction. A three-dimensional shape is a collection of (xi,yi,zi). yi indicates the position in the Y direction.

[0020] The optical displacement meter 1 operates according to instructions from the control device 2. The optical displacement meter 1 outputs a slit light L1 extending in the X direction and receives reflected light L2 from the workpiece W. The optical displacement meter 1 then calculates a profile of the workpiece W based on the light reception result. The optical displacement meter 1 performs imaging at regular intervals to generate profiles of the workpiece W with different yi. In addition, the optical displacement meter 1 generates three-dimensional shape data of the workpiece W from the profiles of the workpiece W with different yi.

[0021] The control device 2 outputs instructions based on user input received by the input device 4 to the optical displacement meter 1, and receives measurement results of the workpiece W from the optical displacement meter 1. The control device 2 also outputs a display signal to the display device 3. The control device 2 is, for example, a personal computer, a programmable logic controller, or the like.

[0022] Based on a display signal from the control device 2, the display device 3 displays, for example, the measurement results of the workpiece W, a UI (user interface) for setting the optical displacement meter 1, and the like.

[0023] The input device 4 accepts a user input to the optical displacement measurement system 100. In Fig. 1, a keyboard and a mouse are illustrated as the input device 4. However, the input device 4 is not limited to a keyboard and a mouse. For example, the input device 4 may be a touch panel arranged on the display screen of the display device 3.

[0024] 2 is a diagram explaining the principle of the light cutting method (triangulation distance measurement). A light projecting unit 11, a light receiving lens 12, and an imaging unit 13 are stored inside a housing 10 of the optical displacement meter 1. The light projecting unit 11 has a light source 14 and a light projecting lens 15. For example, the light source 14 may be a laser light emitter, and the light projecting lens 15 may be composed of a plurality of lenses including a cylindrical lens.

[0025] The light output from the light source 14 is converted into slit light L1 by passing through a light projecting lens 15. The housing 10 is provided with a light projecting window 16 having a light transmitting property that allows the slit light L1 to pass therethrough. Similarly, the housing 10 is provided with a light receiving window 17 having a light transmitting property that allows the reflected light L2 to pass therethrough.

[0026] The light receiving lens 12 is a lens for collecting the reflected light L2 and forming an image on the light receiving surface of the imaging unit 13. The light receiving lens 12 may be configured to include only one lens, or may be configured to include multiple lenses. The light receiving lens 12 may also be configured to include optical components other than lenses (e.g., optical filters, etc.). The imaging unit 13 is an image sensor having multiple photoelectric conversion elements (pixels) arranged two-dimensionally. The imaging unit 13 receives the light collected by the light receiving lens.

[0027] As shown in FIG. 2, the optical axis AX2 of the light receiving lens 12 is inclined with respect to the projection axis AX1 of the light projecting unit 11. The projection axis AX1 of the light projecting unit 11 coincides with the optical axis of the light source 14. As a result, the reflected light L2 from the height Z1 forms an image at a position V1 in the V direction on the light receiving surface of the imaging unit 13, and the reflected light L2 from the height Z2 forms an image at a position V2 in the V direction on the light receiving surface of the imaging unit 13. That is, the V direction of the light receiving surface of the imaging unit 13 corresponds to the Z direction of the workpiece W. Although the U direction of the light receiving surface of the imaging unit 13 is not shown, the U direction corresponds to the X direction of the workpiece W. That is, the vertical direction of the image, which is the light receiving result output by the imaging unit 13, is the V direction, and the horizontal direction is the U direction.

[0028] Light projecting unit 11, light receiving lens 12, and imaging unit 13 are rotatable about rotation axis AX3 along the X direction. The relative positions of light projecting unit 11, light receiving lens 12, and imaging unit 13 are fixed. In Fig. 2, the states of light projecting unit 11, light receiving lens 12, and imaging unit 13 before rotation in the counterclockwise direction CCW are illustrated by solid lines, and the states after rotation in the counterclockwise direction CCW are illustrated by dashed lines.

[0029] The light projecting unit 11, the light receiving lens 12, and the imaging unit 13 can rotate about a rotation axis AX3 along the X direction while satisfying the Scheimpflug relationship in which the light receiving surface of the imaging unit 13 is inclined with respect to the optical axis of the light receiving lens 12. This allows the image to be in focus at each cross section through which the light projecting axis AX1 passes in the shaded area R1 in Fig. 2. In other words, the optical displacement meter 1 can generate a focused profile of the workpiece W even if the height of the workpiece W changes.

[0030] The positional relationship between light projecting unit 11, light receiving lens 12, and imaging unit 13 may be reversed from that shown in FIG.

[0031] 3, the optical displacement meter 1 may further include a reflecting member 18. The reflecting member 18 is provided on the optical path between the light receiving window 17 and the imaging unit 13, and folds back the reflected light L2 and the optical axis AX2 of the light receiving lens 12 toward the light projecting unit 11. This allows the light projecting and receiving module that integrally holds the light projecting unit 11, the light receiving lens 12, the imaging unit 13, and the reflecting member 18 to be configured compactly in the YZ plane extending in the Y and Z directions. This allows the moment of inertia around the rotation axis AX3 of the light projecting and receiving module that integrally holds the light projecting unit 11, the light receiving lens 12, the imaging unit 13, and the reflecting member 18 to be reduced.

[0032] In FIG. 3, the reflecting member 18 is provided on the optical path between the light receiving lens 12 and the imaging section 13, but it may also be provided on the optical path between the light receiving window 17 and the light receiving lens 12 (see, for example, FIG. 8 and FIG. 9 described later).

[0033] When the reflecting member 18 is provided on the optical path between the light-receiving lens 12 and the imaging unit 13, the reflecting member 18 reflects the light after being collected by the light-receiving lens 12, and therefore it is possible to reduce the area of ​​the reflecting surface of the reflecting member 18. When the reflecting member 18 is provided on the optical path between the light-receiving window 17 and the light-receiving lens 12, the heavy light-receiving lens 12 can be disposed closer to the rotation axis AX3, which increases the effect of reducing the moment of inertia.

[0034] <Position (height calculation)> 4 is a diagram for explaining a method for calculating the heights constituting the profile from image I1, which is the light reception result output by image capture unit 13. Slit light L1 has a certain width in the Y direction. Therefore, the width of the light spot brought about by reflected light L2 on the light receiving surface of image capture unit 13 also becomes a width that spans multiple photoelectric conversion elements.

[0035] Therefore, the optical displacement meter 1 obtains an approximation curve P1 indicating the change in luminance value from the luminance value of each pixel, and calculates the position in the V direction that brings about the peak value on the approximation curve P1. In FIG. 4, the leftmost column is the column of interest, and the distribution of luminance values ​​of the column of interest (approximation curve P1) is illustrated. The approximation curve P1 is obtained by curve fitting a plurality of sample values, etc. Sample values ​​below the detection threshold are not taken into consideration. The position in the V direction that brings about this peak value indicates the height of the workpiece W. The optical displacement meter 1 obtains an approximation curve P1 at each position (each pixel column) in the U direction, and calculates the position (height) in the V direction that brings about the peak value from the approximation curve P1. By performing this calculation process at each position in the U direction, one profile is obtained. Such calculation process may be called sub-pixel processing.

[0036] Note that, for example, by calibration before shipment, coordinate conversion conditions (e.g., a coordinate conversion table) indicating the correspondence between the UV coordinates and rotation angle θ, as expressed by (U, V, θ)=(X, Y, Z), and the local coordinates (X, Y, Z) are generated and stored in a memory unit (not shown) of the optical displacement meter 1. Therefore, the optical displacement meter 1 can convert the profile in the UV coordinate system into a profile in the XYZ coordinate system based on the rotation angle θ through simple calculations.

[0037] <Function block> 5 is a functional block diagram of the optical displacement meter 1. The optical displacement meter 1 includes a light emitting and receiving module 20, a motor 21, and a control unit 22.

[0038] The light projecting and receiving module 20 integrally holds the light projecting unit 11, the light receiving lens 12, and the imaging unit 13. In addition, in the case where the optical displacement meter 1 includes a reflecting member 18, the light projecting and receiving module 20 integrally holds the light projecting unit 11, the light receiving lens 12, the imaging unit 13, and the reflecting member 18 (not shown in FIG. 5).

[0039] The motor 21 rotates the light projecting unit 11, the light receiving lens 12, and the imaging unit 13. More specifically, the motor 21 rotates the light projecting and receiving module 20. The motor 21 may rotate the light projecting and receiving module 20 by a direct drive method in which no intermediate mechanism such as a reducer is disposed between the motor 21 and the light projecting and receiving module 20, or may rotate the light projecting and receiving module 20 via an intermediate mechanism such as a reducer.

[0040] The control unit 22 includes a motor control unit 23, a signal processing unit 24, and a communication unit 25. The control unit 22 controls the motor 21 to rotate the light projecting unit 11, the light receiving lens 12, and the imaging unit 13 in a state where the Scheimpflug relationship is satisfied, and scans the slit light L1 in a direction perpendicular to the X direction. More specifically, the motor control unit 23 controls the motor 21 to rotate the light projecting unit 11, the light receiving lens 12, and the imaging unit 13 in a state where the Scheimpflug relationship is satisfied, and the signal processing unit 24 controls the light projecting unit 11 to irradiate the slit light L1 from the light projecting unit 11.

[0041] The signal processing unit 24 includes a peak detection unit 26, a profile generation unit 27, and a three-dimensional data generation unit 28. The peak detection unit 26 detects a position (peak position) in the V direction that brings about a peak in the luminance value based on the light reception result output from the imaging unit 13. The profile generation unit 27 generates one profile data by collecting the heights (zi) of the workpiece W at each position (xi) in the X direction obtained by the peak detection unit 26. The three-dimensional data generation unit 28 generates three-dimensional shape data of the workpiece W from the profiles of the workpiece W having different yi generated by the profile generation unit 27. At least a part of the peak detection unit 26, the profile generation unit 27, and the three-dimensional data generation unit 28 may be provided inside the control device 2 (see FIG. 1) instead of inside the optical displacement meter 1.

[0042] The communication unit 25 performs wired or wireless communication with the control device 2. For example, the communication unit 25 receives instructions from the control device 2 and transmits them to the control unit 22. In addition, the communication unit 25 transmits, for example, profile data and three-dimensional shape data of the workpiece W generated by the signal processing unit 24 to the control device 2.

[0043] <Motor placement> Figures 6 and 7 are diagrams for explaining a first example of the arrangement of the motor 21. Figure 6 is a cross-sectional view perpendicular to the X direction of the optical displacement meter 1 taken along line BB' in Figure 7. Figure 7 is a cross-sectional view along the XZ plane of the optical displacement meter 1 taken along line AA' in Figure 6.

[0044] In the first example, the light emitting and receiving module 20 includes a plate-shaped base member 201 extending along a plane perpendicular to the X direction. The light emitting unit 11, the light receiving lens 12, the imaging unit 13, and the reflecting member 18 are mounted on the base member 201.

[0045] In the first example, the light projecting and receiving module 20 does not overlap with the motor 21 and the accessories of the motor 21 in the X direction. The accessories of the motor 21 are, for example, an encoder that detects the amount of rotation of the rotor of the motor 21. According to the first example of the arrangement of the motor 21, it is easy to arrange the light projecting unit 11, the light receiving lens 12, and the imaging unit 13 close to each other. By arranging the light projecting unit 11, the light receiving lens 12, and the imaging unit 13 close to each other, the light projecting and receiving module 20 can be configured to be compact. Therefore, the moment of inertia around the rotation axis AX3 of the light projecting and receiving module 20 can be reduced.

[0046] In the first example, the control unit 22 does not overlap with the light emitting and receiving module 20 in the X direction, but overlaps with the motor 21 in the X direction.

[0047] Figures 8 and 9 are diagrams for explaining a second example of the arrangement of the motor 21. Figure 8 is a cross-sectional view perpendicular to the X direction of the optical displacement gauge 1 taken along line BB' in Figure 9. Figure 9 is a cross-sectional view perpendicular to the Z direction of the optical displacement gauge 1 taken along line AA' in Figure 8.

[0048] In the second example, the light emitting / receiving module 20 includes a base member 201. The base member 201 includes a tube portion extending along the X direction, a cover portion closing one end of the tube portion in the X direction, and a flange portion extending radially outward from the other end of the tube portion in the X direction. The light emitting unit 11, the light receiving lens 12, the imaging unit 13, and the reflecting member 18 are mounted on the flange portion of the base member 201.

[0049] In the second example, the light-emitting / receiving module 20 overlaps with at least one of the motor 21 and an accessory of the motor 21 in the X direction. As in the first example, the accessory of the motor 21 is, for example, an encoder that detects the amount of rotation of the rotor of the motor 21. According to the second example of the arrangement of the motor 21, it becomes easy to arrange the light-emitting unit 11 away from the light-receiving lens 12 and the imaging unit 13. By separating the light-emitting unit 11 from the light-receiving lens 12 and the imaging unit 13, the scanning range of the slit light L1 can be expanded.

[0050] Furthermore, in the second example, the control unit 22 overlaps with the light emitting and receiving module 20 and the motor 21 in the X direction. Note that the control unit 22 may be disposed in a position that does not overlap with the motor 21 in the X direction but overlaps with the motor 21 as viewed from the X direction. When the control unit 22 is disposed in a position that does not overlap with the motor 21 in the X direction but overlaps with the motor 21 as viewed from the X direction, the control unit 22 may or may not overlap with the light emitting and receiving module 20 and the motor 21 in the X direction.

[0051] <Processing flow> Fig. 10 is a diagram showing a process flow of the measurement operation of the optical displacement measurement system 100. When the input device 4 receives a user input instructing the start of measurement, the process flow of Fig. 10 starts.

[0052] First, in step S1, the light projector 11 starts emitting the slit light L1. In the following step S2, the motor control unit 23 starts rotating the motor 21. Note that the processing of step S1 and the processing of step S2 may be executed simultaneously. Before executing step S1, the motor control unit 23 may rotate the motor to move the light projector / receive module 20 to a predetermined scanning start position. The processing of steps S1 and S2 starts scanning with the slit light L1.

[0053] In the next step S3, the motor control unit 23 determines whether the amount of rotation (rotation angle) of the motor 21 from the start of rotation is smaller than a threshold value. If the amount of rotation of the motor 21 from the start of rotation is smaller than the threshold value, the determination process of step S3 continues, and the scanning of the slit light L1 continues.

[0054] When the amount of rotation of the motor 21 from the start of rotation reaches the threshold, the flow proceeds to step S4. The threshold is the amount of rotation calculated based on the measurement range. The measurement range is set as a default, and when the measurement range is changed by the user, the control unit 22 (e.g., the signal processing unit 24) calculates the threshold of the amount of rotation based on the measurement range after the change.

[0055] In step S4, motor control unit 23 stops the rotation of motor 21. In the following step S5, light projector 11 stops emitting slit light L1. Note that steps S4 and S5 may be performed simultaneously. The scanning of slit light L1 is completed by the processes of steps S4 and S5.

[0056] In the next step S6, the profile generator 27 generates a profile. The profile generator 27 may start generating a profile during scanning with the slit light L1.

[0057] In the following step S7, the three-dimensional data generator 28 generates three-dimensional data.

[0058] In the following step S8, the display device 3 displays the measurement results. The measurement results are, for example, a cross-sectional view of the workpiece W based on the profile, a three-dimensional image of the workpiece W based on the three-dimensional data, etc. When the process of step S8 ends, the process flow of FIG. 10 ends.

[0059] The optical displacement meter 1 has a measurement period in which the measurement operation is performed by rotating the light emitting and receiving module 20 at a substantially constant speed in a first rotation direction (counterclockwise direction CCW) or a second rotation direction (clockwise direction CW), and a non-measurement period in which the rotation direction of the light emitting and receiving module 20 is switched but the measurement operation is not performed. In the measurement period in which the measurement operation is performed, the motor rotates the light emitting and receiving module 20 at a substantially constant speed. The period in which the rotation direction is switched needs to take deceleration and acceleration into consideration, and calculations such as the correlation between the peak position in the V direction and the rotation angle become complicated, so it is preferable to make it a non-measurement period.

[0060] <Bandpass filter> The light projecting and receiving module 20 has a bandpass filter 30 (see FIGS. 11 to 15 described later) that passes light in a first wavelength range included in the slit light L1. The light receiving window 17 transmits light in a wavelength range that includes the first wavelength range and is wider than the first wavelength range. The reflected light L2 that passes through the light receiving window 17 passes through the bandpass filter 30 and enters the imaging unit 13. With this configuration, the incident angle of the reflected light L2 to the bandpass filter 30 is not affected by a change in the angle between the optical axis AX2 of the light receiving lens 12 and the light receiving window 17. As a result, there is no change in the incident angle of the reflected light of the slit light to the bandpass filter, so that it is possible to suppress deterioration of the performance of the bandpass filter 30 in preventing the intrusion of disturbance light.

[0061] 16 is a diagram showing an example of the relationship between the wavelength range W1 of the slit light irradiated from the light projector 11, the transmission characteristic 101 of the bandpass filter 30, and the transmission characteristic 102 of the light-receiving window 17 when the light source 14 is a blue laser light emitter. The transmittance of the bandpass filter 30 for a predetermined wavelength range including the wavelength range of the slit light L1 is higher than the transmittance of the bandpass filter 30 outside the predetermined wavelength range. The wavelength range of light that can pass through the bandpass filter 30 with a transmittance of 50% or more is narrower than the wavelength range of light that can pass through the light-receiving window 17 with a transmittance of 50% or more.

[0062] The light receiving window 17 may be configured, for example, not to include an optical filter, or may be configured to include an optical filter that has a wider range of wavelengths of light that can pass through with a transmittance of 50% or more than the bandpass filter 30, or may be configured with a colored glass filter.

[0063] For example, the bandpass filter 30 is disposed in the light projecting and receiving module 20 at a position that is approximately perpendicular to the optical axis AX2 of the light receiving lens 12 regardless of the rotation of the light projecting and receiving module 20. This arrangement eliminates the need for a design that takes into consideration the change in the optical characteristics of the bandpass filter 30 when light is not perpendicularly incident on the bandpass filter 30 compared to when light is perpendicularly incident on the bandpass filter 30.

[0064] The bandpass filter 30 may be provided on the surface of the light receiving lens 12, for example, as shown in FIG.

[0065] When the light-receiving lens 12 includes a plurality of lenses, the bandpass filter 30 may be provided inside the light-receiving lens 12, for example, as shown in FIG. 12. In FIG. 12, the bandpass filter 30 is held by a flat plate-shaped holding member 31. The holding member 31 may have the same light transmittance as the light-receiving window 17, for example. The bandpass filter 30 is composed of a plurality of optical thin films laminated on the light-receiving lens 12 or the holding member 31. The bandpass filter 30 may also be provided on the surface of each of the plurality of lenses. In this case, since a plurality of bandpass filters can be used, the overall effect of the bandpass filter can be improved.

[0066] The bandpass filter 30 may be provided on a cover glass 33 that covers the light receiving surface 131 of the imaging section 13, for example, as shown in Figures 13 and 14. The cover glass 33 may be disposed perpendicular to the optical axis AX2 of the light receiving lens 12 as shown in Figure 13, or may be disposed parallel to the light receiving surface 131 of the imaging section 13 as shown in Figure 14. The bandpass filter 30 is composed of a plurality of optical thin films laminated on the cover glass 33. The cover glass 33 is generally smaller than the light receiving lens 12 and the reflecting member 18, and therefore costs can be reduced.

[0067] The bandpass filter 30 may be provided on the reflecting member 18, for example, as shown in Fig. 15. The bandpass filter 30 is composed of a plurality of optical thin films laminated on the reflecting member 18. Since the angle between the reflecting member 18 and the imaging unit 13 is relatively large, even if multiple reflection occurs between the optical thin films, the possibility of the light being incident on the imaging unit 13 is reduced. The light emitting / receiving module 20 may include a plurality of bandpass filters 30, in which case any of the above arrangements may be combined.

[0068] The light projecting and receiving module 20 holds the bandpass filter 30 so that the angle between the optical axis AX2 of the light receiving lens 12 and the light receiving window 17 changes within a predetermined angle range due to the rotation of the light projecting and receiving module 20, while the angle between the optical axis AX2 of the light receiving lens 12 and the bandpass filter 30 is constant regardless of the rotation angle of the light projecting and receiving module 20. Since the light collected by the light receiving lens is incident on the bandpass filter at a constant angle, the reflected light of the slit light is prevented from being filtered by the bandpass filter. More specifically, the light projecting and receiving module 20 holds the bandpass filter 30 indirectly via the components included in the light projecting and receiving module 20 (e.g., the light receiving lens 12, the holding member 31, the cover glass 33, the reflecting member 18, etc.). The above-mentioned predetermined angle range may be, for example, a range including 85 degrees to 95 degrees. Furthermore, the light projecting and receiving module 20 is fixed so that the light projecting axis of the light projecting unit 11, the light receiving lens 12, and the image capturing unit 13 satisfy the Scheimpflug relationship regardless of the rotation angle during measurement operation, and further includes a base member 201 to which a bandpass filter 30 is fixed in a position relative to the light receiving lens 12, so that the reflected light of the slit light reflected by a workpiece positioned at the focal plane of the Scheimpflug relationship is incident on the bandpass filter 30 at a constant incident angle regardless of the rotation angle. This makes it possible to obtain a profile image by the reflected light of the focused slit light while suppressing the effects of disturbance light.

[0069] For example, when bandpass filter 30 is provided on the surface of light-receiving lens 12, bandpass filter 30 is not arranged along a plane. When bandpass filter 30 is not arranged along a plane, the angle between a virtual plane tangent to the center of bandpass filter 30 and optical axis AX2 of light-receiving lens 12 becomes the angle between optical axis AX2 of light-receiving lens 12 and bandpass filter 30.

[0070] It is preferable that the angle between the optical axis AX2 of the light receiving lens 12 and the bandpass filter 30 is included in the above-mentioned predetermined angle range. It is more preferable that the angle between the optical axis AX2 of the light receiving lens 12 and the bandpass filter 30 is an angle at approximately the center of the above-mentioned predetermined angle range. It is even more preferable that the optical axis AX2 of the light receiving lens 12 and the bandpass filter 30 are approximately perpendicular to each other. This is because, when the optical axis AX2 of the light receiving lens 12 and the bandpass filter 30 are approximately perpendicular to each other, it becomes unnecessary to design the bandpass filter 30 taking into consideration the change in the optical characteristics of the bandpass filter 30 when light is not perpendicularly incident on the bandpass filter 30 compared to when light is perpendicularly incident on the bandpass filter 30.

[0071] <Colored glass filters> The light receiving window 17 may be formed of a colored glass filter that passes light in the first wavelength range contained in the slit light L1. In this case, the optical displacement meter 1 may be configured without the above-mentioned bandpass filter 30. Generally, a bandpass filter (optical thin film filter) has sharper transmission characteristics than a colored glass filter and can narrow the wavelength range with high transmittance, so the influence of ambient light may be further suppressed by further providing a bandpass filter 30.

[0072] The colored glass filter constituting the light-receiving window 17 has substantially constant transmission characteristics for light in a predetermined wavelength range, regardless of changes in the incident angle of the reflected light L2 with respect to the light-receiving window 17 caused by the rotation of the light-emitting and receiving module 20. As a result, the optical characteristics of the colored glass filter for light in a first wavelength range including the wavelength range of the slit light L1 are substantially constant, regardless of the angle between the light-receiving window 17 and the optical axis AX2 of the light-receiving lens 12. Therefore, it is possible to suppress deterioration of the performance for preventing the intrusion of disturbance light due to changes in the angle between the light-receiving window 17 and the optical axis AX2 of the light-receiving lens 12.

[0073] The colored glass filter constituting the light receiving window 17 passes infrared light. In other words, the colored glass filter constituting the light receiving window 17 has low performance in preventing the intrusion of infrared disturbance light. However, since a typical imaging unit 13 has low sensitivity to infrared light, the low performance in preventing the intrusion of infrared disturbance light is not a major problem.

[0074] <Summary> The various embodiments described above will be generally described below.

[0075] For example, a first optical displacement meter disclosed in this specification includes a light projecting / receiving module having a light projecting unit that irradiates a slit light extending in the X direction, a light receiving lens that collects reflected light of the slit light reflected by a workpiece, a bandpass filter whose relative position with the light receiving lens is fixed, and an imaging unit that receives the light collected by the light receiving lens, a motor that rotates the light projecting / receiving module as a unit, a housing that stores the light projecting / receiving module and has a light receiving window that transmits the reflected light, and a control unit that controls the motor and scans the slit light in a direction perpendicular to the X direction, and the light receiving window transmits light of a predetermined wavelength range including the wavelength range of the slit light regardless of the rotation angle of the light projecting / receiving module during measurement operation, and the bandpass filter selectively passes or reflects the reflected light of the slit light out of the light that has transmitted through the light receiving window, causing it to be incident on the imaging unit (first configuration).

[0076] In the optical displacement meter of the first configuration described above, the angle between the optical axis of the light-receiving lens and the light-receiving window changes within a predetermined angle range as the light-emitting and receiving module rotates, while the band-pass filter may be held by the light-emitting and receiving module so that the angle between the optical axis of the light-receiving lens and the band-pass filter is constant regardless of the rotation angle of the light-emitting and receiving module (second configuration).

[0077] In an optical displacement meter having the above first or second configuration, the light projecting and receiving module may further have a support member for fixing the light projecting axis of the light projecting unit, the light receiving lens, and the imaging unit so as to satisfy a Scheimpflug relationship regardless of the rotation angle during the measurement operation, and for fixing the bandpass filter in the relative position with the light receiving lens, and the reflected light of the slit light reflected by the work located at a focal plane of the Scheimpflug relationship may be configured to be incident on the bandpass filter at a constant incident angle regardless of the rotation angle (third configuration).

[0078] In an optical displacement meter having any of the above first to third configurations, the bandpass filter may be arranged within the light-emitting and receiving module at a position approximately perpendicular to the optical axis of the light-receiving lens regardless of rotation of the light-emitting and receiving module, and the reflected light that passes through the light-receiving window may pass through the bandpass filter, causing light in the wavelength range of the slit light to be incident on the imaging unit (fourth configuration).

[0079] In an optical displacement meter having any one of the first to fourth configurations described above, the imaging section may have a plurality of pixels arranged two-dimensionally and a cover glass that protects the plurality of pixels, and the bandpass filter may be configured (fifth configuration) to be composed of a plurality of optical thin films stacked on the cover glass.

[0080] In the optical displacement meter having the fifth configuration described above, the cover glass and the bandpass filter may be configured (sixth configuration) to be approximately perpendicular to the optical axis of the light receiving lens regardless of rotation of the light emitting and receiving module, and to be arranged at an angle with respect to the light receiving surfaces of the multiple pixels.

[0081] In an optical displacement meter having any of the above first to sixth configurations, the light receiving lens may include a plurality of lenses, the bandpass filter being provided on each lens surface of the plurality of lenses, and the light transmitted through the light receiving window may sequentially pass through the bandpass filters provided on each lens surface, thereby selectively causing the reflected light of the slit light to be incident on the imaging unit (sixth configuration).

[0082] In an optical displacement meter having any of the above-mentioned configurations 1 to 7, the light emitting / receiving module may further have a reflecting member that is arranged on the optical path between the light receiving window and the imaging unit and has a fixed relative position with respect to the light receiving lens, the bandpass filter is composed of a plurality of optical thin films stacked on the reflecting member, and the reflecting member and the bandpass filter may be configured (8th configuration) to selectively reflect the reflected light of the slit light toward the imaging unit among the light that passes through the light receiving window and is incident on the bandpass filter and the reflecting member at a predetermined angle.

[0083] In the optical displacement meter of the above-mentioned eighth configuration, the light projecting and receiving module may further have a support member (ninth configuration) that fixes the light projecting axis of the light projecting unit, the light receiving lens, the reflecting member, and the imaging unit so that they satisfy the Scheimpflug relationship regardless of the rotation angle during the measurement operation.

[0084] In an optical displacement meter having any of the above configurations 1 to 9, the light receiving window may be configured with a colored glass filter that has an approximately constant transmittance in the specified wavelength range regardless of changes in the angle of incidence, and whose transmittance in a first wavelength range including the wavelength range of the slit light is higher than the transmittance outside the first wavelength range and within the specified wavelength range, and the colored glass filter transmits light in the first wavelength range regardless of the rotation angle of the light projecting and receiving module during the measurement operation, and the bandpass filter may be configured to selectively pass or reflect the reflected light of the slit light from the light that has transmitted through the colored glass filter, causing it to be incident on the imaging unit (configuration 10).

[0085] For example, a second optical displacement meter disclosed in this specification includes a light projecting and receiving module having a light projecting unit that irradiates a slit light extending in an X direction, a light receiving lens that collects reflected light of the slit light reflected by a workpiece, and an imaging unit that receives the light collected by the light receiving lens, a motor that rotates the light projecting and receiving module as a unit, a housing that stores the light projecting and receiving module and has a light receiving window that transmits the reflected light, and a control unit that controls the motor and scans the slit light in a direction perpendicular to the X direction, wherein the light receiving window has a substantially constant transmittance in a predetermined wavelength range that includes the wavelength range of the slit light regardless of changes in the angle of incidence, and is formed of a colored glass filter whose transmittance in the wavelength range of the slit light is higher than the transmittance of the slit light outside the wavelength range and within the predetermined wavelength range, and the colored glass filter is configured to selectively pass the reflected light of the slit light and cause it to be incident on the imaging unit regardless of the rotation angle of the light projecting and receiving module during measurement operation (eleventh configuration).

[0086] <Other Modifications> In addition to the above-mentioned embodiment, various technical features disclosed in this specification can be modified in various ways without departing from the spirit of the technical creation. In other words, the above-mentioned embodiment should be considered to be illustrative and not restrictive in all respects, and the technical scope of the present invention is defined by the claims, and should be understood to include all modifications that fall within the meaning and scope equivalent to the claims. [Explanation of symbols]

[0087] 1. Optical displacement gauge 2. Control device 3 Display device 4 Input Devices 10. Housing 11 Light projector 12 Receiving lens 13 Imaging unit 131 Photosensitive surface 14 Light source 15 Projection lens 16 Floodlight 17 Light receiving window 18 Reflective material 20 Light emitting / receiving module 201 Base material 21 Motor 22 Control section 23 Motor control unit 24 Signal Processing Section 25 Communications Department 26 Peak detector 27 Profile Generation Unit 28 3D Data Generation Division 30 Bandpass Filter 31 Retaining member 33 Coverslip 100 Optical Displacement Measurement System AX1 light emitting axis AX2 optical axis I1 Image AX3 Rotation Axis R1 area W work

Claims

1. a light projecting and receiving module including a light projecting unit that projects a slit light extending in the X direction, a light receiving lens that collects light reflected from the slit light by a workpiece, a band pass filter whose relative position with respect to the light receiving lens is fixed, and an imaging unit that receives the light collected by the light receiving lens; a motor for rotating the light emitting and receiving modules together; a housing that houses the light emitting and receiving module and has a light receiving window that transmits the reflected light; a control unit that controls the motor to cause the slit light to scan in a direction perpendicular to the X direction, An optical displacement meter in which the light receiving window transmits light of a predetermined wavelength range including the wavelength range of the slit light regardless of the rotation angle of the light emitting and receiving module during measurement operation, and the bandpass filter selectively passes or reflects the reflected light of the slit light from the light that has transmitted through the light receiving window, causing it to be incident on the imaging unit.

2. 2. The optical displacement meter according to claim 1, wherein the angle between the optical axis of the light-receiving lens and the light-receiving window changes within a predetermined angle range upon rotation of the light-emitting and receiving module, while the angle between the optical axis of the light-receiving lens and the bandpass filter is constant regardless of the rotation angle of the light-emitting and receiving module.

3. the light-projecting and light-receiving module further includes a support member that fixes the light-projecting axis of the light-projecting unit, the light-receiving lens, and the imaging unit so as to satisfy a Scheimpflug relationship regardless of the rotation angle during the measurement operation, and that fixes the bandpass filter in the relative position with respect to the light-receiving lens; 2. The optical displacement meter according to claim 1, wherein the reflected light of the slit light reflected by the workpiece located at a focal plane in the Scheimpflug relationship is incident on the bandpass filter at a constant incident angle regardless of the rotation angle.

4. the bandpass filter is disposed in the light emitting / receiving module at a position substantially perpendicular to an optical axis of the light receiving lens regardless of rotation of the light emitting / receiving module, The optical displacement meter according to claim 1 , wherein the reflected light that has passed through the light receiving window passes through the bandpass filter, so that light in the wavelength range of the slit light is incident on the imaging section.

5. the imaging unit includes a plurality of pixels arranged two-dimensionally and a cover glass that protects the plurality of pixels; 2. The optical displacement meter according to claim 1, wherein the bandpass filter is composed of a plurality of optical thin films laminated on the cover glass.

6. 6. The optical displacement meter according to claim 5, wherein the cover glass and the bandpass filter are disposed substantially perpendicular to an optical axis of the light receiving lens regardless of rotation of the light emitting and receiving module, and obliquely with respect to the light receiving surfaces of the plurality of pixels.

7. the light receiving lens includes a plurality of lenses, and the band pass filter is provided on a surface of each of the plurality of lenses; 2. The optical displacement meter according to claim 1, wherein the light transmitted through the light receiving window passes sequentially through the bandpass filters provided on the surfaces of the lenses, so that the reflected light of the slit light is selectively incident on the imaging section.

8. the light emitting / receiving module further includes a reflecting member that is disposed on an optical path between the light receiving window and the imaging unit and has a fixed position relative to the light receiving lens; the bandpass filter is formed of a plurality of optical thin films laminated on the reflecting member, 2. The optical displacement meter according to claim 1, wherein the reflecting member and the bandpass filter selectively reflect the reflected light of the slit light, among the light that has passed through the light receiving window and is incident on the bandpass filter and the reflecting member at a predetermined angle, toward the imaging unit.

9. 9. The optical displacement meter according to claim 8, wherein the light projecting and receiving module further includes a support member to which the light projecting unit, the light receiving lens, the reflecting member, and the imaging unit are fixed so as to satisfy a Scheimpflug relationship regardless of the rotation angle during the measurement operation.

10. the light receiving window is configured with a color glass filter having a substantially constant transmittance in the predetermined wavelength range regardless of a change in the angle of incidence, and a transmittance in a first wavelength range including the wavelength range of the slit light is higher than a transmittance outside the first wavelength range and within the predetermined wavelength range, The colored glass filter transmits light in the first wavelength range regardless of a rotation angle of the light emitting / receiving module during the measurement operation, and the bandpass filter selectively transmits or reflects the reflected light of the slit light among the light transmitted through the colored glass filter, and causes it to be incident on the imaging unit.

2. The optical displacement meter according to claim 1.

11. a light projecting and receiving module including a light projecting unit that projects a slit light extending in the X direction, a light receiving lens that collects light reflected by a workpiece from the slit light, and an imaging unit that receives the light collected by the light receiving lens; a motor for rotating the light emitting and receiving modules together; a housing that houses the light emitting and receiving module and has a light receiving window that transmits the reflected light; a control unit that controls the motor to cause the slit light to scan in a direction perpendicular to the X direction, the light receiving window is made of a color glass filter that has a substantially constant transmittance regardless of a change in the angle of incidence in a predetermined wavelength range including the wavelength range of the slit light, and the transmittance in the wavelength range of the slit light is higher than the transmittance of the slit light outside the wavelength range and within the predetermined wavelength range; The colored glass filter selectively transmits the reflected light of the slit light and allows it to be incident on the imaging unit, regardless of the rotation angle of the light emitting and receiving module during measurement operation.

Images