Displacement measuring device and display program

Abstract

This technology reduces the manufacturing cost of displacement measuring devices while improving their measurement accuracy. [Solution] The displacement measuring device 100 of the present disclosure comprises at least a first irradiation unit 10, a first light receiving unit 20, a second irradiation unit 30, and a second light receiving unit 40. The first light receiving unit 20 includes a two-dimensionally arranged first light receiving element 21 and a first microlens 22 two-dimensionally arranged on the light receiving surface 21s side of the first light receiving element 21. The second light receiving unit 40 includes a two-dimensionally arranged second light receiving element 41 of the same type as the first light receiving element 21 and a second microlens 42 two-dimensionally arranged on the light receiving surface 41s side of the second light receiving element 41. The device further comprises an optical system that emits second reflected light RL2 incident along the optical axis through the second microlens 42 within an angular range in which the light receiving surface 41s of the second light receiving element 41 can receive the light.

Description

Technical Field

[0001] The present disclosure relates to a displacement measuring device and a display program.

Background Art

[0002] Techniques for optically measuring displacements occurring in a measurement target are known.

[0003] For example, in Patent Document 1, there is a mirror provided on a measurement target, having a reflection portion narrowed down to a spot shape and a one-dimensional diffraction grating arranged on top of the reflection portion, an irradiation means for irradiating the reflection portion with measurement light having an irradiation range wider than the reflection portion with respect to the mirror so that the reflection portion is included in the irradiation range, a spectroscopic means for splitting the 0th-order reflected light from the reflection portion into a first light beam and a second light beam, a first sensor for receiving the first light beam and outputting a signal corresponding to the light reception position, a second sensor for receiving the second light beam and outputting a signal corresponding to the light reception position, a third sensor for receiving the 1st-order reflected light from the reflection portion and outputting a signal corresponding to the light reception position, assuming that a first axis and a second axis are taken in directions orthogonal to each other in a plane orthogonal to the irradiation direction of the measurement light with respect to the mirror, and a third axis is taken in a direction orthogonal to both the first axis and the second axis, displacement detection means for detecting angular displacements around the respective axes of the first axis and the second axis of the measurement target based on the signal output by the first sensor, detecting axial displacements in the directions of the first axis and the second axis of the measurement target based on the signal output by the second sensor, and detecting an angular displacement around the third axis of the measurement target based on the signal output by the third sensor, is disclosed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] As disclosed in Patent Document 1, when measuring axial displacement along with angular displacement, two light-receiving elements are required. However, in order to reduce the manufacturing cost of the displacement measuring device, it is desirable to standardize parts by using two light-receiving elements of the same type.

[0006] Incidentally, to accurately detect the beam spot of reflected light from the object to be measured, it is desirable to use a two-dimensional photodetector with higher resolution than a one-dimensional photodetector. However, typical two-dimensional photodetectors are used with microlenses to improve light detection sensitivity, making it difficult to receive reflected light that is incident at an oblique angle to the light-receiving surface. Therefore, if an optical arrangement following the so-called Scheinproof law is adopted, which improves measurement accuracy by causing reflected light to be incident at an oblique angle to the light-receiving surface of the photodetector so that an image is formed so that it is in focus on the light-receiving surface, the amount of light received is greatly reduced, and it becomes impossible to secure an appropriate signal strength. Consequently, with conventional technology, it has been difficult to reduce the manufacturing cost of displacement measurement devices while improving measurement accuracy.

[0007] In light of these circumstances, the purpose of this disclosure is to provide a technology that reduces the manufacturing cost of displacement measuring devices and improves their measurement accuracy. [Means for solving the problem]

[0008] A displacement measuring device according to one embodiment of the present disclosure includes: a first irradiation unit that irradiates a measurement target with first irradiation light from a first irradiation direction; a first light receiving unit that receives first reflected light generated when the first irradiation light is reflected by the measurement target and measures at least one of angular displacement around an axis intersecting the first irradiation direction and axial displacement along an axis intersecting the first irradiation direction; a second irradiation unit that irradiates the measurement target with second irradiation light from a second irradiation direction inclined obliquely with respect to the first irradiation direction; and a second light receiving unit that receives second reflected light generated when the second irradiation light is reflected by the measurement target and measures along an axis parallel to the first irradiation direction. A displacement measuring device comprising at least a first light-receiving unit for measuring axial displacement, wherein the first light-receiving unit includes a two-dimensionally arranged first light-receiving element and a first microlens two-dimensionally arranged on the light-receiving surface side of the first light-receiving element, and the second light-receiving unit includes a two-dimensionally arranged second light-receiving element of the same type as the first light-receiving element and a second microlens two-dimensionally arranged on the light-receiving surface side of the second light-receiving element, and further comprises an optical system that emits the second reflected light incident along the optical axis through the second microlens within an angular range in which the light-receiving surface of the second light-receiving element can receive light.

[0009] A display program according to one embodiment of the present disclosure is a display program for displaying the measurement results of a displacement measuring device on a display device, and causes a processor in the display device to perform the following operations: to acquire a first output from a first light receiving unit in the displacement measuring device; to generate a first two-dimensional image based on the acquired first output, which is associated with at least one of an angular displacement around an axis intersecting a first irradiation direction to the object to be measured and an axial displacement on an axis intersecting the first irradiation direction; to acquire a second output from a second light receiving unit in the displacement measuring device; to generate a second two-dimensional image based on the acquired second output, which shows the position of at least one reflection point of the second irradiation light on the object to be measured; to generate a screen including at least one of the generated first two-dimensional image and the generated second two-dimensional image; and to display the generated screen on the display device. [Effects of the Invention]

[0010] According to one embodiment of the present disclosure, the manufacturing cost of the displacement measuring device can be reduced, and the measurement accuracy can be improved. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic diagram showing an example of the configuration of a displacement measuring device according to one embodiment of the present disclosure. [Figure 2] This is a flowchart illustrating an example of processing by the calculation unit of a displacement measuring device according to one embodiment of the present disclosure. [Figure 3] This figure illustrates the two-dimensional image in the processing example shown in Figure 2. [Figure 4] This figure illustrates an example of a screen display output from an output processing unit of a displacement measuring device according to one embodiment of the present disclosure. [Figure 5] This is a schematic diagram showing an example of the configuration of a displacement measuring device according to one modified example of the present disclosure. [Modes for carrying out the invention]

[0012] Hereinafter, an embodiment of this disclosure will be described in detail with reference to the attached drawings. In this specification and the drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant descriptions will be omitted.

[0013] (0.definition) In this specification, with respect to the first irradiation direction of the first irradiation light IL1 irradiated onto the object to be measured 1, the directions that are mutually orthogonal in a plane perpendicular to the first irradiation direction are defined as the X-axis direction and the Y-axis direction, and the direction perpendicular to the X-axis direction and the Y-axis direction is defined as the Z-axis direction. However, these definitions are for illustrative purposes only and do not unduly limit this disclosure.

[0014] (1. Displacement measuring device) Referring to FIG. 1, the displacement measuring device 100 according to the present embodiment is a device that measures the displacement of the measurement object 1. Specifically, the displacement measuring device 100 measures the angular displacement θx around the X-axis of the measurement object 1 corresponding to the angular displacement around the axis intersecting the first irradiation direction and the angular displacement θy around the Y-axis of the measurement object 1, and the axial displacement δz along the Z-axis direction of the measurement object 1 corresponding to the axial displacement on the axis along the first irradiation direction. The displacement measuring device 100 includes at least a first irradiation unit 10, a first light receiving unit 20, a second irradiation unit 30, and a second light receiving unit 40.

[0015] (1-1. Measurement Object) The measurement object 1 is, for example, any object that specularly reflects the first irradiation light IL1 and the second irradiation light IL2. The reference plane of the measurement object 1 is set to be parallel to the X-axis and Y-axis and perpendicular to the Z-axis in an initial state where neither axial displacement nor angular displacement occurs. In the example shown in FIG. 1, the state where the measurement object 1 is located at Z0 on the Z-axis is the initial state.

[0016] (1-2. First Irradiation Unit) The first irradiation unit 10 irradiates the measurement object 1 with the first irradiation light IL1 from the first irradiation direction. Specifically, the first irradiation unit 10 may include a first light source 11, a collimating lens 12, and a half mirror 13.

[0017] The first light source 11 is, for example, a laser diode, but the present disclosure is not limited thereto, and a light source other than the laser diode may be used. In the example shown in FIG. 1, the first light source 11 is arranged such that its optical axis is along the X-axis direction. The collimating lens 12 shapes the light emitted from the first light source 11 into a parallel light beam having a circular cross section. The half mirror 13 receives the parallel light beam shaped by the collimating lens 12 and reflects it along the Z-axis direction corresponding to the first irradiation direction, guiding it to the measurement object 1 as the first irradiation light IL1. When the measurement object 1 is in the initial state, the optical axis AX1 of the first irradiation light IL1 is set to coincide or substantially coincide with, for example, the center of the measurement object 1.

[0018] (1-3. First Light Receiving Unit) The first light-receiving unit 20 is a light-receiving unit that receives the first reflected light RL1 generated by the reflection of the first irradiation light IL1 on the measurement target 1 and measures θx and θy corresponding to the angular displacement around the axis intersecting the first irradiation direction. The first light-receiving unit 20 includes at least a two-dimensionally arranged first light-receiving element 21 and a two-dimensionally arranged first microlens 22 on the light-receiving surface 21s side of the first light-receiving element 21. Hereinafter, the first light-receiving element 21 and the first microlens 22 will be specifically described.

[0019] The first light-receiving element 21 includes, for example, a light-receiving surface 21s formed by two-dimensionally arranging a plurality of photodiodes, and converts the first reflected light RL1 received by each photodiode into an electrical signal. Thereby, the first light-receiving element 21 outputs an electrical signal corresponding to the light-receiving position of the first reflected light RL1 on the light-receiving surface 21s. Examples of the first light-receiving element 21 include any photoelectric conversion type sensor such as a CCD (Charge Coupled Device) sensor or a CMOS (Complementary Metal Oxide Semiconductor) sensor. The first light-receiving element 21 is arranged such that, for example, the light-receiving surface 21s is orthogonal or substantially orthogonal to the direction of the optical axis AX1 of the first irradiation light IL1, and the first reflected light RL1 is received at the center of the light-receiving surface 21s when the measurement target 1 is in the initial state.

[0020] The first microlens 22 is two-dimensionally arranged corresponding to each of the plurality of photodiodes included in the first light-receiving element 21, and condenses the first reflected light RL1 on the light-receiving surface 21s of the first light-receiving element 21. The first microlens 22 may be configured as a so-called microlens array in which a plurality of microlenses are two-dimensionally arranged.

[0021] In addition, the first light-receiving unit 20 may further include an optical system 23 composed of one or more lenses that condense the first reflected light RL1 that has passed through the half mirror 13 and form an image on the light-receiving surface 21s of the first light-receiving element 21 in cooperation with the first microlens 22.

[0022] (1-4.Second irradiation section) The second irradiation unit 30 irradiates the measurement target 1 with second irradiation light IL2 from a second irradiation direction that is inclined obliquely with respect to the first irradiation direction. Specifically, the second irradiation unit 30 may include a second light source 31 and a light projection lens 32.

[0023] The second light source 31 is, for example, a laser diode, but the disclosure is not limited thereto, and light sources other than laser diodes may be used. However, in order to reduce the manufacturing cost of the displacement measuring device 100 by standardizing parts, it is preferable that the second light source 31 is of the same type as the first light source 11. In the example shown in Figure 1, the second light source 31 is arranged such that its optical axis AX2 is tilted by an inclination angle φ with respect to the Z axis direction in the XZ plane. The inclination angle φ is, for example, 45 degrees, but the disclosure is not limited thereto, and the optimal angle can be set for each model of the displacement measuring device 100 depending on the size of the displacement measuring device 100 and the distance from the displacement measuring device 100 to the reference plane of the object to be measured 1.

[0024] The projection lens 32 is composed of one or more lenses. The projection lens 32 focuses the light emitted from the second light source 31 and images it onto the measurement target 1 as the second illumination light IL2. As a result, the second reflected light RL2 corresponding to the second illumination light IL2 is emitted towards the second light receiving unit 40. However, the light emitted from the second light source 31 does not need to be completely focused onto the measurement target 1. If a long measurement range is desired for the displacement measuring device 100, the beam diameter will change depending on the installation position of the measurement target 1, so for example, parallel light may be emitted.

[0025] (1-5. 2nd light receiving section) The second light-receiving unit 40 is a light-receiving unit that receives the second reflected light RL2 generated when the second irradiated light IL2 is reflected by the measurement target 1, and measures δz which corresponds to the axial displacement along the axis along the first irradiation direction. The second light-receiving unit 40 includes a second light-receiving element 41 of the same type as the first light-receiving element 21, arranged in two dimensions, and a second microlens 42 arranged in two dimensions on the light-receiving surface 41s side of the second light-receiving element 41. The second light-receiving element 41 and the second microlens 42 will be described in detail below.

[0026] The second light-receiving element 41 includes a light-receiving surface 41s formed by a two-dimensional arrangement of multiple photodiodes, and converts the second reflected light RL2 received by each photodiode into an electrical signal. As a result, the second light-receiving element 41 outputs an electrical signal corresponding to the light-receiving position of the second reflected light RL2 on the light-receiving surface 41s. The second light-receiving element 41 is not particularly limited as long as it is the same type as the first light-receiving element 21, and any photoelectric conversion type sensor such as a CCD sensor or CMOS sensor is exemplified. The light-receiving surface 41s of the second light-receiving element 41 is arranged in a direction perpendicular or substantially perpendicular to the optical axis of the second reflected light RL2, such that the second light-receiving unit 40 is positioned perpendicular or substantially perpendicular to the optical axis of the second reflected light RL2. Furthermore, the second light-receiving element 41 is positioned such that, for example, when the measurement target 1 is in its initial state, the second reflected light RL2 is received at the center of the light-receiving surface 41s of the second light-receiving element 41.

[0027] The second microlens 42 is arranged in two dimensions corresponding to each of the multiple photodiodes included in the second photodetector 41, and focuses the second reflected light RL2 onto the light-receiving surface 41s of the second photodetector 41. The second microlens 42 may be configured as a so-called microlens array, similar to the first microlens 22, in which multiple microlenses are arranged in two dimensions.

[0028] (1-6. Optical System: Bilateral telecentric optical system) Here, it is important that the displacement measuring device 100 according to this embodiment includes an optical system that emits the second reflected light RL2 incident along the optical axis via the second microlens 42 within an angular range in which the light-receiving surface 41s of the second photodetector 41 can receive the light. The technical significance of this will be explained below.

[0029] To measure both the angular and axial displacement of the object to be measured 1, two light-receiving elements are required. However, in order to reduce the manufacturing cost of the displacement measuring device 100 by standardizing parts, it is desirable to use the same type of first light-receiving element 21 and second light-receiving element 41. This allows for the standardization of not only the first light-receiving element 21 and second light-receiving element 41, but also the electrical signal processing circuits 64 output by each of the first and second light-receiving elements 21 and second light-receiving element 41, thereby further reducing manufacturing costs.

[0030] Furthermore, in order to improve the measurement accuracy of the displacement measuring device 100, it is desirable to use two-dimensional photodetectors with higher resolution than one-dimensional photodetectors as the first photodetector 21 and the second photodetector 41. However, if an optical arrangement following Scheinproof's law is adopted to improve measurement accuracy, it is necessary to cause the second reflected light RL2 to be incident at an oblique angle to the light-receiving surface 41s of the second photodetector 41, and the second photodetector 41 will hardly be able to receive the second reflected light RL2. This is because, if the second reflected light RL2 is incident at an oblique angle, for example, more than ±24 degrees, to the normal of the light-receiving surface 41s of the second photodetector 41, the incident position of the second reflected light RL2 will deviate from the light-receiving surface 41s of the second photodetector 41 due to refraction of the second microlens 42, etc.

[0031] Therefore, in this embodiment, an optical system is arranged to emit the second reflected light RL2 incident along the optical axis through the second microlens 42 within an angular range that can be received by the light-receiving surface 41s of the second photodetector 41. This makes it possible to improve the measurement accuracy of the displacement measuring device 100 without adopting an optical arrangement that follows Scheinproof's law. The angular range is preferably such that the angle of incidence of the second reflected light RL2 with respect to the normal of the light-receiving surface 41s of the second photodetector 41 is within ±24 degrees, more preferably within ±15 degrees, and even more preferably within ±5 degrees when there is no angular displacement in the object to be measured 1. The angular range of the second reflected light RL2 incident on the second microlens 42 can be set based on the refractive index of the second microlens 42 and the wavelength of the second reflected light RL2, and can be set to a range in which the second reflected light RL2 refracted by the second microlens 42 can reach the light-receiving surface 41s of the second photodetector 41.

[0032] In the example shown in Figure 1, the displacement measuring device 100 includes a double-sided telecentric optical system 50 positioned between the object to be measured 1 and the second light-receiving unit 40, which is an optical system that emits the second reflected light RL2 incident along the optical axis through the second microlens 42 within an angular range in which the light-receiving surface 41s of the second light-receiving element 41 can receive the light. Specifically, the double-sided telecentric optical system 50 includes one or more object-side lenses 51 of a telecentric optical system that converts the second reflected light RL2 from the object to be measured 1 into parallel light, and one or more image-side lenses 52 of a telecentric optical system that images the parallel light onto the light-receiving surface 41s of the second light-receiving element 41.

[0033] When the position of the object to be measured 1 in the Z-axis direction is displaced, the second reflected light RL2 from the object to be measured 1 is focused at a different light-receiving position on the light-receiving surface 41s of the second light-receiving element 41. In the example shown in Figure 1, the position of the object to be measured 1 in the Z-axis direction changes from Z0 to Z + When displaced, the second reflected light RL2 from the measurement target 1 changes from RL2(Z0) to RL2(Z +) changes, and consequently, the light-receiving position on the light-receiving surface 41s of the second light-receiving element 41 changes. Also, the position of the measurement target 1 in the Z axis changes from Z0 to Z - When displaced, the second reflected light RL2 from the measurement target 1 changes from RL2(Z0) to RL2(Z - ) changes, and consequently, the light-receiving position on the light-receiving surface 41s of the second light-receiving element 41 changes. Even in this situation, the second reflected light RL2 can be incident on the second microlens 42 at an angle closer to perpendicular than when the same measurement is performed without employing the double-sided telecentric optical system 50. For example, by employing the double-sided telecentric optical system 50, the second reflected light RL2 can be incident on the normal to the light-receiving surface 41s of the second light-receiving element 41 at, for example, within ±5 degrees when there is no angular displacement in the measurement target 1. Even when there is angular displacement in the measurement target 1, the second reflected light RL2 can be incident on the normal to the light-receiving surface 41s of the second light-receiving element 41 at, for example, within ±15 degrees. Therefore, even if the same type of two-dimensional photodetector is used as the first photodetector 21 and the second photodetector 41 in order to achieve both a reduction in the manufacturing cost of the displacement measuring device 100 and an improvement in measurement accuracy, the second photodetector 41 can stably receive the second reflected light RL2.

[0034] However, this disclosure is not necessarily limited to the double-sided telecentric optical system 50, and any optical system can be appropriately employed as long as it is possible to emit the second reflected light RL2 incident along the optical axis through the second microlens 42 within an angular range in which the light-receiving surface 41s of the second photodetector 41 can receive the light.

[0035] (1-7. Computer Unit) The displacement measuring device 100 may further include a light source control unit 61, a calculation unit 62, and an output processing unit 63. The light source control unit 61, the calculation unit 62, and the output processing unit 63 are functions realized by the execution of a computer program by a processor such as a CPU (Central Processing Unit) included in a computer unit 60 installed in the displacement measuring device 100. The computer unit 60 may further include a memory such as RAM (Random Access Memory) or ROM (Read Only Memory) that is connected to the processor in a communicative manner. The memory appropriately stores the computer program executed by the light source control unit 61, the calculation unit 62, and the output processing unit 63, various parameters used in the calculation process, and calculation results.

[0036] (1-7-1. Light source control unit) When the measurement of the displacement of the object to be measured 1 begins, the light source control unit 61 executes control to turn on the first light source 11 and the second light source 31. The light receiving timing of the first light receiving element 21 is preset to be synchronized with the light emission timing of the first light source 11. The light receiving timing of the second light receiving element 41 is also preset to be synchronized with the light emission timing of the second light source 31.

[0037] Here, if the first light source 11 and the second light source 31 are composed of the same type of light source, if the first light source 11 and the second light source 31 are lit simultaneously, the light from each other may become a noise source, which may affect the measurement. Therefore, it is preferable for the light source control unit 61 to perform control that staggers the light emission timing of the first light source 11 and the light emission timing of the second light source 31. Specifically, it is preferable for the light source control unit 61 to turn on the first light source 11 and turn off the second light source 31 for a first time interval (e.g., 100 milliseconds), and then to turn off the first light source 11 and turn on the second light source 31 for a second time interval (e.g., 100 milliseconds), and to repeat this series of controls during the measurement. However, the order in which the first light source 11 and the second light source 31 are turned on and off is not limited to this, and may be reversed.

[0038] The first and second time intervals may each be set within a range of 5 milliseconds to 2000 milliseconds, or within a range of 10 milliseconds to 1000 milliseconds. However, this disclosure is not limited to these, as long as the emission timings of the first light source 11 and the second light source 31 can be staggered relative to each other. Furthermore, the first and second time intervals may coincide or be different.

[0039] (1-7-2. Arithmetic section) The calculation unit 62 calculates θx and θy, which correspond to the angular displacement around the axis intersecting the first irradiation direction of the object to be measured 1, based on the output from the first light receiving unit 20.

[0040] Specifically, when at least one of the angular displacements θx and θy occurs in the object being measured 1, the reflection direction of the first reflected light RL1 from the object being measured 1 shifts from the optical axis AX1, and the position at which the first reflected light RL1 is received on the light-receiving surface 21s of the first light-receiving element 21 changes according to the direction and amount of this shift. Therefore, the calculation unit 62 identifies the direction and amount of change in the position at which the first reflected light RL1 is received on the light-receiving surface 21s of the first light-receiving element 21, for example, when the object being measured 1 is in its initial state, as a reference. Then, the calculation unit 62 converts the identified direction and amount of change into angular displacements θx and θy, respectively, according to the geometric relationship between the object being measured 1 and the first light-receiving element 21.

[0041] Meanwhile, the calculation unit 62 identifies the position of at least one reflection point of the second irradiated light IL2 at the measurement target 1 based on the output from the second light receiving unit 40. Specifically, the calculation unit 62 acquires the output from the second light receiving unit 40 as two-dimensional array data and identifies the position of at least one reflection point of the second irradiated light IL2 at the measurement target 1 based on the acquired two-dimensional array data. In the following, this embodiment will be described using, for example, the case in which the two-dimensional array data is handled as a two-dimensional image 81 in which pixels indicating the received intensity of the second reflected light RL2 are arranged in the x and y directions, as shown in Figure 3. However, as will be described later, if, instead of the two-dimensional image 81 being displayed on the screen, the coordinate position of the reflection point of the second irradiated light IL2 is displayed on the screen as text, for example, the two-dimensional array data does not necessarily have to be handled as an image.

[0042] Here, the light-receiving positions on the light-receiving surface 41s of the second photodetector 41, which are associated with the reflection points of the second irradiated light IL2, are distributed over a range with a certain degree of spread depending on the light-receiving intensity of the second reflected light RL2, thereby forming the intensity distribution of the second reflected light RL2. Therefore, in order to more accurately determine the position and number of reflection points, it is preferable for the calculation unit 62 to calculate the centroid position of the intensity distribution of the second reflected light RL2 from the two-dimensional image 81. Below, with reference to Figures 2 and 3, an example of how the calculation unit 62 calculates the centroid position of the intensity distribution of the second reflected light RL2 will be described.

[0043] In step S1, the calculation unit 62 acquires the received intensity of the second reflected light RL2 received by each photodiode on the light-receiving surface 41s of the second light-receiving element 41. Note that this received intensity may be averaged over a predetermined time period, which can be appropriately set, from the viewpoint of suppressing noise and improving measurement accuracy. The process then proceeds to step S2.

[0044] In step S2, the calculation unit 62 generates a two-dimensional image 81 in which pixels indicating the received intensity of the second reflected light RL2 acquired in step S1 are arranged in a two-dimensional manner to correspond to the two-dimensional arrangement of each photodiode on the light-receiving surface 41s of the second light-receiving element 41. Figure 3 also shows a magnified two-dimensional image 82, which is an enlarged view of the two-dimensional image 81, and the numerical values ​​shown for each of the 100 pixels (10 in the x direction and 10 in the y direction) are examples of the received intensity of the second reflected light RL2. Note that, in order to reduce the processing load, the calculation unit 62 generates the two-dimensional image 81 by extracting only the pixels corresponding to a predetermined area irradiated by the second reflected light RL2 from all the photodiodes on the light-receiving surface 41s of the second light-receiving element 41. The process then proceeds to step S3.

[0045] In step S3, the calculation unit 62 forms clusters in the two-dimensional image 81 or the two-dimensional enlarged image 82 generated in step S2 by concatenating pixels in which the received light intensity of the second reflected light RL2 is equal to or greater than a threshold. This threshold can be set appropriately depending on the structure or type of the object to be measured 1. The process then proceeds to step S4.

[0046] In step S4, the arithmetic unit 62 assigns labels to the clusters formed in step S3. In the example shown in Figure 3, three clusters are labeled as cluster C1, cluster C2, and cluster C3. The process then proceeds to step S5.

[0047] In step S5, the calculation unit 62 calculates the centroid position of the intensity distribution of the second reflected light RL2 for the clusters that were labeled in step S4. In the example shown in Figure 3, the centroid position G1 is calculated for cluster C1, the centroid position G2 is calculated for cluster C2, and the centroid position G3 is calculated for cluster C3. The process then proceeds to step S6.

[0048] In step S6, the calculation unit 62 determines whether the calculation of the centroid position of the intensity distribution of the second reflected light RL2 has been completed for all clusters that were labeled in step S4. If it is determined that the calculation of the centroid position has been completed (step S6: YES), the process ends. If it is determined that the calculation of the centroid position has not been completed (step S6: NO), the process returns to step S5.

[0049] As described above, through the processing in steps S1 to S6, the calculation unit 62 can calculate the centroid position of the intensity distribution of the second reflected light RL2, which is associated with the reflection points of the second irradiated light IL2. Therefore, even if the light-receiving positions on the light-receiving surface 41s of the second photodetector 41 are distributed over a certain extent, the position and number of reflection points of the second irradiated light IL2 can be determined more accurately. This is also useful when multiple reflection points are formed due to multiple reflections caused by the measurement target 1 being a thin film or the like. Furthermore, the calculation unit 62 can also calculate the centroid position of the intensity distribution of the second reflected light RL2 as a one-dimensional image in the x direction by integrating the intensity distribution of the second reflected light RL2 shown in Figure 3 in the y direction.

[0050] The calculation unit 62 can calculate δz, which corresponds to the axial displacement along the axis parallel to the first irradiation direction, based on the centroid position of the intensity distribution of the second reflected light RL2 calculated by, for example, the processing example shown in Figure 2. Specifically, when the object to be measured 1 is displaced along the Z-axis direction, the light-receiving position of the second reflected light RL2 on the light-receiving surface 41s of the second light-receiving element 41 changes, and the centroid position of the light-receiving intensity also changes accordingly. Therefore, the calculation unit 62 identifies the direction and amount of change in the centroid position, for example, using the centroid position when the object to be measured 1 is in its initial state as a reference, and converts the identified direction and amount of change into an axial displacement δz according to the geometric relationship between the object to be measured 1 and the second light-receiving element 41.

[0051] (1-7-3. Output Processing Unit) Referring to Figure 4, the output processing unit 63 is: -A two-dimensional image 83 associated with θx and θy, which correspond to the angular displacement around the axis intersecting the first irradiation direction, generated based on the output from the first light receiving unit 20, - A two-dimensional image 81 (or two-dimensional enlarged image 82) showing the position of at least one reflection point of the second irradiated light IL2 in the measurement target 1, which is generated based on the output from the second light receiving unit 40, A screen 84 is generated that includes at least one of the following.

[0052] The output processing unit 63 may generate a screen 84 that includes a two-dimensional image 83 on which the angular displacements θx and θy calculated by the calculation unit 62 are plotted on a two-dimensional plane with θx as the horizontal axis and θy as the vertical axis, and output the generated screen 84. An example of the output method is displaying the screen on a known or arbitrary monitor (not shown) connected to the displacement measuring device 100 via wired or wireless connection. This allows the user to visually grasp the magnitudes of the angular displacements θx and θy of the measurement target 1 on the two-dimensional image 83.

[0053] Additionally or alternatively, the output processing unit 63 may generate a two-dimensional image 81 (or a two-dimensional magnified image 82) showing the centroid position of the intensity distribution of the second reflected light RL2 corresponding to the position of at least one reflection point of the second irradiated light IL2 identified by the calculation unit 62, and output the generated screen 84. Examples of output modes include screen display on a known or arbitrary monitor (not shown) connected to the displacement measuring device 100 via wired or wireless connection. This allows the user to visually grasp the position and number of reflection points by visually viewing the centroid position of the intensity distribution of the second reflected light RL2 in two dimensions. As a result, the user can determine whether or not the Z-axis measurement is being performed accurately. For example, the two-dimensional magnified image 82 shown in Figure 4 shows multiple beam spots that were unclear in a one-dimensional image from a conventional one-dimensional photodetector, allowing the user to clearly understand that multiple reflection points are occurring in the measurement target 1.

[0054] Furthermore, the output processing unit 63 may include in the screen 84 described above an image in which the intensity (integral value) of the second reflected light RL2, calculated by integrating the intensity distribution of the second reflected light RL2 in the y direction, is associated with the axial displacement δz calculated from the centroid position of the intensity distribution of the second reflected light RL2, as shown in the lower right of Figure 4.

[0055] (1-8. Others) The displacement measuring device 100 may further include known or arbitrary holders (not shown) for holding the first irradiation unit 10, the first light receiving unit 20, the second irradiation unit 30, the second light receiving unit 40, and the double-sided telecentric optical system 50, respectively. The displacement measuring device 100 may also further include known or arbitrary housing 70 for housing the first irradiation unit 10, the first light receiving unit 20, the second irradiation unit 30, the second light receiving unit 40, the double-sided telecentric optical system 50, and the computer unit 60. However, windows 71 are appropriately formed on the measurement target 1 side of the housing 70 for passing the first irradiation light IL1, the second irradiation light IL2, the first reflected light RL1, and the second reflected light RL2, respectively. In addition to the light source control unit 61, calculation unit 62, and output processing unit 63 described above, the displacement measuring device 100 may further include a function processing unit that is provided for known or arbitrary displacement measuring devices, as a function realized by the execution of a computer program by the processor included in the computer unit 60. The computer unit 60 may be located outside the housing 70.

[0056] (1-9. Summary) As described above, the displacement measuring device 100 according to this embodiment is - A first irradiation unit 10 that irradiates the measurement target 1 with the first irradiation light IL1 from the first irradiation direction, -A first light receiving unit 20 receives the first reflected light RL1 generated when the first irradiated light IL1 is reflected by the measurement target 1, and measures θx and θy which correspond to the angular displacement around the axis intersecting the first irradiation direction, - A second irradiation unit 30 that irradiates the measurement target 1 with a second irradiation light IL2 from a second irradiation direction that is inclined diagonally with respect to the first irradiation direction, -A second light receiving unit 40 receives the second reflected light RL2 generated when the second irradiated light IL2 is reflected by the measurement target 1, and measures δz which corresponds to the axial displacement along the axis in the first irradiation direction, It must have at least the following:

[0057] In particular, the first light-receiving unit 20 includes a two-dimensionally arranged first light-receiving element 21 and a first microlens 22 two-dimensionally arranged on the light-receiving surface 21s side of the first light-receiving element 21. The second light-receiving unit 40 includes a two-dimensionally arranged second light-receiving element 41 of the same type as the first light-receiving element 21 and a second microlens 42 two-dimensionally arranged on the light-receiving surface 41s side of the second light-receiving element 41. Furthermore, the displacement measuring device 100 includes a double-sided telecentric optical system 50 which corresponds to an optical system that emits second reflected light RL2 incident along the optical axis through the second microlens 42 within an angular range in which the light-receiving surface 41s of the second light-receiving element 41 can receive the light.

[0058] With this configuration, by using the same type of first light-receiving element 21 and second light-receiving element 41, parts can be standardized, thereby reducing the manufacturing cost of the displacement measuring device 100. Furthermore, when employing two-dimensional light-receiving elements, which have higher resolution than one-dimensional light-receiving elements, as the first light-receiving element 21 and second light-receiving element 41, for example, a double-sided telecentric optical system 50 is employed. This makes it possible to improve the measurement accuracy of the displacement measuring device 100 without employing an optical arrangement that follows Scheinproof's law, which makes light reception difficult for two-dimensional light-receiving elements. Therefore, according to this embodiment, the manufacturing cost of the displacement measuring device 100 can be reduced, and the measurement accuracy can be improved.

[0059] Although one embodiment of the present disclosure has been described in detail above with reference to the attached drawings, the present disclosure is not limited to this example. It is clear to any person with ordinary skill in the art to which the present disclosure belongs that various modifications or alterations can be conceived within the scope of the technical idea described in the claims, and these will naturally also be understood to fall within the technical scope of the present disclosure. For example, the functions and so on included in each component can be rearranged in a logically consistent manner, and multiple components can be combined into one or separated.

[0060] (2-1. First variation) Referring to Figure 5, the displacement measuring device 200 according to the first modified example differs from the embodiment described above in that it further includes at least a reflective mirror (second reflective mirror 54) that folds back the optical path of the second reflected light RL2. The differences from the embodiment described above will be mainly explained below, and other details will be based on the description of the embodiment described above.

[0061] The first illumination unit 10 may include a first light source 11, a projection lens 14, a half mirror 13, and a collimating lens 15. In the example shown in Figure 5, the first light source 11 is positioned so that its optical axis is aligned with the Z-axis direction. The projection lens 14 focuses the light emitted from the first light source 11 and guides it to the half mirror 13. The half mirror 13 allows the light from the projection lens 14 to pass through and guides it to the collimating lens 15. The collimating lens 15 makes the light from the half mirror 13 collimated light and guides it to the measurement target 1 as first illumination light IL1 aligned with the Z-axis direction corresponding to the first illumination direction. The first light source 11 can be configured in the same way as in the embodiments described above.

[0062] The first light-receiving unit 20 is a light-receiving unit that receives the first reflected light RL1 reflected by the half mirror 13 and measures θx and θy, which correspond to the angular displacement around the axis intersecting the first irradiation direction. In the example shown in Figure 5, the first reflected light RL1 reflected by the half mirror 13 is along the X-axis. The first light-receiving unit 20 includes a two-dimensionally arranged first light-receiving element 21 and a first microlens 22 two-dimensionally arranged on the light-receiving surface 21s side of the first light-receiving element 21, similar to the embodiment described above. The position of the first light-receiving element 21 on the axis of the first reflected light RL1 is set at a position where the parallel light reflected from the measurement target 1 is focused by the collimating lens 15.

[0063] The second illumination unit 30 may include a second light source 31, a projection lens 32, and a first reflective mirror 33. In the example shown in Figure 5, the second light source 31 is positioned so that its optical axis is aligned with the Z-axis direction. The projection lens 32 focuses the light emitted from the second light source 31 and guides it to the first reflective mirror 33. The first reflective mirror 33 reflects the light from the projection lens 32 and guides it to the measurement target 1 as second illumination light IL2 from a second illumination direction that is tilted obliquely with respect to the first illumination direction. The second light source 31 can be configured in the same way as in the embodiments described above.

[0064] Because the optical path of the light from the second light source 31 is folded back by the first reflective mirror 33, unlike the embodiment described above, it is not necessary to position the second light source 31 on the extension of the second irradiation direction to the measurement target 1, and an arrangement can be adopted in which the optical axis of the second light source 31 is aligned with the Z-axis direction. Therefore, the first irradiation unit 10, the first light receiving unit 20, the second irradiation unit 30, the second light receiving unit 40, the double-sided telecentric optical system 50, and the computer unit 60 can be housed in a miniaturized housing 70. As a result, the entire displacement measuring device 200 can be miniaturized. However, the first reflective mirror 33 may be omitted as appropriate depending on the requirements for miniaturization of the displacement measuring device 200. In addition, the computer unit 60 may be placed outside the housing 70.

[0065] The displacement measuring device 200 according to the first modified example includes a double-sided telecentric optical system 50 positioned between the object to be measured 1 and the second light-receiving unit 40. The double-sided telecentric optical system 50 includes an object-side lens 51 of the telecentric optical system positioned on the object to be measured 1 side and an image-side lens 53 of the telecentric optical system positioned on the second light-receiving unit 40 side. The displacement measuring device 200 also includes a second reflective mirror 54 between the object-side lens 51 and the image-side lens 53 that folds back the optical path of the second reflected light RL2 from the object to be measured 1. Specifically, the second reflective mirror 54 reflects the second reflected light RL2 from the object to be measured 1 that has passed through the object-side lens 51 and causes it to enter the image-side lens 53. As a result, the second reflected light RL2 from the object to be measured 1 is folded back by the second reflective mirror 54 before reaching the second light-receiving unit 40, thus allowing the displacement measuring device 200 to be miniaturized.

[0066] The object-side lens 51 of the telecentric optical system can be composed of one or more lenses, as in the embodiments described above. On the other hand, unlike the embodiments described above, it is important that the image-side lens 53 of the telecentric optical system is composed of at least two lenses 53a and 53b. This allows the focal length to be shortened compared to when the image-side lens 53 is composed of one lens, and thus the optical path from the second reflecting mirror 54 to the second light-receiving unit 40 can be shortened. Therefore, the displacement measuring device 200 can be miniaturized, and interference between the second light-receiving unit 40 and the light emitted from the first light source 11 can be prevented. In other words, even if the displacement measuring device 200 is miniaturized using the second reflecting mirror 54, it does not affect the measurement of θx and θy, which correspond to the angular displacement around the axis intersecting the first irradiation direction.

[0067] The second light-receiving unit 40 is a light-receiving unit that receives the second reflected light RL2 that has passed through the image-side lens 53 of the telecentric optical system and measures δz, which corresponds to the axial displacement along the axis in the first irradiation direction. The second light-receiving unit 40 includes a second light-receiving element 41 arranged in two dimensions and a second microlens 42 arranged in two dimensions on the light-receiving surface 41s side of the second light-receiving element 41, similar to the embodiment described above.

[0068] The displacement measuring device 200 may also be equipped with a computer unit 60, similar to the embodiment described above, and may further include a light source control unit 61, a calculation unit 62, and an output processing unit 63 as functions realized by the execution of a computer program by the processor included in the computer unit 60. The processing contents of the light source control unit 61, the calculation unit 62, and the output processing unit 63 will be described by referring to the description in the embodiment described above.

[0069] (2-2. Second variation) As a second modification, the first light-receiving unit 20 may be a light-receiving unit for measuring δx and δy, which correspond to axial displacements on the axis intersecting the first irradiation direction, in addition to θx and θy, which correspond to angular displacements around the axis intersecting the first irradiation direction. In this case, the first reflected light RL1 from the object to be measured 1 is appropriately spectrally separated using known or arbitrary spectral means (not shown) such as a half mirror, prism, or beam splitter, and is guided to a light-receiving element (not shown) configured similarly to the first light-receiving element 21 via known or arbitrary optical system (not shown) as needed. Unlike the first modification, the position of the first light-receiving element 21 on the axis of the first reflected light RL1 is set at the position where the image of the object to be measured 1 is formed by the collimating lens 15. Furthermore, a mirror or the like with a diameter sufficiently smaller than the beam diameter of the first irradiation light IL1 may be installed on the object to be measured 1. The calculation unit 62 determines the direction and amount of change in the reception position of the first reflected light RL1 on the light-receiving surface of the light-receiving element, for example, when the object to be measured 1 is in its initial state, using the reception position of the first reflected light RL1 as a reference. Then, the calculation unit 62 converts the determined direction and amount of change into axial displacements δx and δy, respectively, according to the geometric relationship between the object to be measured 1 and the light-receiving element. The axial displacements δx and δy can also be visualized to the user as a two-dimensional image by undergoing the same processing as in the embodiment described above.

[0070] (2-3. Third variation) As a third modification, the technology of this disclosure can also be realized as a display program that displays the measurement results of the displacement measuring devices 100, 200 according to the above-described embodiment or modification on a display device (not shown), or as a non-temporary computer-readable medium on which the display program is recorded. Specifically, the display program according to the third modification is transmitted to a processor such as a CPU in the display device. - To acquire the first output from the first light receiving unit 20 of the displacement measuring device 100, 200, - Based on the acquired first output, a first two-dimensional image (e.g., two-dimensional image 83) is generated, which is associated with at least one of θx and θy, which correspond to the angular displacement around the axis intersecting the first irradiation direction for the measurement target 1, and δx and δy, which correspond to the axial displacement along the axis intersecting the first irradiation direction. - To acquire the second output from the second light receiving unit 40 of the displacement measuring device 100, 200, - Based on the acquired second output, a second two-dimensional image (e.g., a two-dimensional enlarged image 82) is generated that shows the position of at least one reflection point of the second irradiation light IL2 at the measurement target 1. - To generate a screen 84 that includes at least one of the generated first two-dimensional image and the generated second two-dimensional image, - To display the generated screen 84 on the display device, Perform an action that includes this.

[0071] The generation of the first two-dimensional image and the second two-dimensional image can be performed in the same manner as the processing performed by the calculation unit 62 and output processing unit 63 in the above-described embodiment or modified example. Furthermore, while a personal computer that can be connected to the displacement measuring devices 100,200 by wire or wireless means is an example of a display device, this disclosure is not limited thereto, and any device can be used as long as it is capable of performing the above-described operations. [Explanation of symbols]

[0072] 100,200: Displacement measuring device, 1: Measurement target, 10: First irradiation unit, 11: First light source, 12: Collimating lens, 13: Half mirror, 14: Projection lens, 15: Collimating lens, 20: First light receiving unit, 21: First light receiving element, 21s: Light receiving surface, 22: First microlens, 23: Optical system, 30: Second irradiation unit, 31: Second light source, 32: Projection lens, 33: First reflective mirror, 40: Second light receiving unit, 41: Second light receiving element, 41s: Light receiving surface, 42: Second micro Chlorine lens, 50: double-sided telecentric optical system, 51: object-side lens, 52, 53, 53a, 53b: image-side lenses, 54: second reflection mirror, 60: computer unit, 61: light source control unit, 62: calculation unit, 63: output processing unit, 64: processing circuit, 70: housing, 71: window section, 81: two-dimensional image, 82: two-dimensional enlarged image, 83: two-dimensional image, 84: screen, IL1: first illumination light, IL2: second illumination light, RL1: first reflected light, RL2: second reflected light

Claims

1. A first irradiation unit that irradiates the object to be measured with first irradiation light from a first irradiation direction, A first light receiving unit receives the first reflected light generated when the first irradiated light is reflected by the object to be measured, and measures at least one of the angular displacement about an axis intersecting the first irradiation direction and the axial displacement along the axis intersecting the first irradiation direction. A second irradiation unit that irradiates the measurement target with a second irradiation light from a second irradiation direction that is inclined obliquely with respect to the first irradiation direction, A second light receiving unit receives the second reflected light generated when the second irradiation light is reflected by the object to be measured, and measures the axial displacement along the axis in the first irradiation direction, A displacement measuring device comprising at least the following: The first light-receiving unit includes a first light-receiving element arranged in two dimensions and a first microlens arranged in two dimensions on the light-receiving surface side of the first light-receiving element. The second light-receiving unit includes a second light-receiving element of the same type as the first light-receiving element, arranged in a two-dimensional manner, and a second microlens arranged in a two-dimensional manner on the light-receiving surface side of the second light-receiving element. The optical system further comprises a second microlens that causes the second reflected light, incident along the optical axis, to be emitted within an angular range in which the light-receiving surface of the second photodetector can receive the light, Displacement measuring device.

2. The optical system is a double-sided telecentric optical system arranged between the object to be measured and the second light-receiving unit. The displacement measuring device according to claim 1.

3. The system further comprises at least one reflective mirror that folds back the optical path of the second reflected light, The reflective mirror reflects the second reflected light that has passed through the object-side lens of the telecentric optical system located on the measurement target side of the two-sided telecentric optical system, and causes the second reflected light to enter the image-side lens of the telecentric optical system located on the second light-receiving side of the two-sided telecentric optical system. The aforementioned image-side lens includes at least two lenses, The displacement measuring device according to claim 2.

4. The first irradiation unit includes a first light source, The second irradiation unit includes a second light source of the same type as the first light source, The system further includes a light source control unit that performs control to shift the light emission timing of the first light source and the light emission timing of the second light source. The displacement measuring device according to claim 1.

5. The system further includes a calculation unit that acquires the output from the second light receiving unit as two-dimensional array data and determines the position of at least one reflection point of the second irradiated light on the measurement target based on the acquired two-dimensional array data. The displacement measuring device according to claim 1.

6. The output processing unit further comprises generating a screen that includes at least one of the following: a two-dimensional image associated with at least one of the angular displacement around the axis intersecting the first irradiation direction and the axial displacement on the axis intersecting the first irradiation direction, which are generated based on the output from the first light receiving unit; and a two-dimensional image showing the position of at least one reflection point of the second irradiation light on the measurement target, which are generated based on the output from the second light receiving unit, and outputting the generated screen. The displacement measuring device according to claim 1.

7. A display program for displaying the measurement results of the displacement measuring device described in claim 1 on a display device, The processor included in the aforementioned display device To acquire the first output from the first light receiving unit of the displacement measuring device, Based on the acquired first output, a first two-dimensional image is generated that corresponds to at least one of the angular displacement around an axis intersecting the first irradiation direction to the object being measured and the axial displacement along the axis intersecting the first irradiation direction. The second output from the second light receiving unit of the displacement measuring device is to be acquired, Based on the acquired second output, a second two-dimensional image is generated showing the position of at least one reflection point of the second irradiation light on the measurement target, To generate a screen that includes at least one of the generated first two-dimensional image and the generated second two-dimensional image, The generated screen is displayed on the display device, A display program that performs actions including those mentioned above.

Images