Three-dimensional measuring device

Abstract

Provided is a three-dimensional measurement device capable of achieving an improvement in measurement accuracy or the like. A three-dimensional measurement device (1) includes an interference optical system (3) having a half mirror (HM) that splits incident light into two lights, irradiates one of the split lights to a workpiece (W), and irradiates the other light to a reference surface (23), recombines and emits them, a first light projecting system (2A) that emits first light of a first wavelength toward the half mirror (HM), a second light projecting system (2B) that emits second light of a second wavelength toward the half mirror (HM), a first imaging system (4A) that images output light related to the first light emitted from the half mirror (HM), and a second imaging system (4B) that images output light related to the second light emitted from the half mirror (HM), is configured to perform three-dimensional measurement of the workpiece (W) based on image data acquired by the imaging systems (4A, 4B), and the traveling directions of the first light and the second light toward the workpiece (W) are different, and the traveling directions of the first light and the second light toward the reference surface (23) are different.

Description

Technical Field

[0001] This invention relates to a three-dimensional measuring device for measuring the shape of an object to be measured. Background Technology

[0002] Previously, three-dimensional measuring devices utilizing interferometers were known as measuring devices for measuring the shape of an object. In recent years, in order to expand the measurement range, three-dimensional measuring devices utilizing two types of light with different wavelengths have also been proposed (for example, see Patent Document 1).

[0003] In the three-dimensional measurement device described in Patent Document 1, by incident two kinds of light with different wavelengths from different positions of the polarization beam splitter, the wavelength difference between the two kinds of light can be minimized, which can greatly expand the measurement range.

[0004] Usually, such as Figure 16 As shown, the three-dimensional measurement device using an interferometer includes: a polarization beam splitter (PBS) 100; a light source 101 that emits coherent light incident on the polarization beam splitter 100; and an imaging device 102 that captures the light emitted from the polarization beam splitter 100.

[0005] exist Figure 16 In the example shown, polarized light of a specified wavelength (polarized light whose polarization direction is tilted at 45° relative to the X-axis and Y-axis directions) is emitted downward from the light source 101 in the Z-axis direction and incident on the first surface 100a of the polarization beam splitter 100.

[0006] Light incident from the first surface 100a of the polarization beam splitter 100 branches in two directions at the boundary surface 100e of the polarization beam splitter 100, and its P-polarized component (which will be combined with the polarization beam splitter)... Figure 16 Linearly polarized light (parallel to the paper surface, polarization direction) passes downwards along the Z-axis and exits from the third surface 100c as the measurement light. On the other hand, its S-polarized component (which will be...) Figure 16 The linearly polarized light (with the Y-axis direction perpendicular to the paper as the polarization direction) is reflected to the right in the X-axis direction and emitted from the fourth surface 100d as the reference light.

[0007] The measurement light (P-polarized light) emitted from the third surface 100c of the polarizing beam splitter 100 is converted into right-handed circularly polarized light after passing through the quarter-wave plate 103, and is then reflected by the workpiece 110. Here, the rotational direction of the light relative to the direction of travel is maintained. Then, the measurement light passes through the quarter-wave plate 103 again, thereby being converted from right-handed circularly polarized light into S-polarized light, and then re-enters the third surface 100c of the polarizing beam splitter 100.

[0008] On the other hand, the reference light (S-polarized light) emitted from the fourth surface 100d of the polarization beam splitter 100 is converted into left-handed circularly polarized light after passing through the quarter-wave plate 104, and then reflected by the reference surface 111. Here, the rotation direction of the light relative to the direction of travel is maintained. Afterwards, the reference light passes through the quarter-wave plate 104 again, thereby being converted from left-handed circularly polarized light into P-polarized light, and then re-incidentally enters the fourth surface 100d of the polarization beam splitter 100.

[0009] Then, the measurement light (S-polarized light) that is incident again from the third surface 100c of the polarization beam splitter 100 is reflected to the left in the X-axis direction at the boundary surface 100e. On the other hand, the reference light (P-polarized light) that is incident again from the fourth surface 100d is transmitted to the left in the X-axis direction at the boundary surface 100e. Thus, the composite light combining the measurement light and the reference light is emitted as the output light from the second surface 100b of the polarization beam splitter 100.

[0010] The combined light (measurement light and reference light) emitted from the second surface 100b of the polarization beam splitter 100 first passes through the quarter-wave plate 105, which converts its measurement light component (S-polarized light component) into left-handed circularly polarized light and its reference light component (P-polarized light component) into right-handed circularly polarized light. Here, the left-handed and right-handed circularly polarized light do not interfere with each other because of their different rotation directions.

[0011] The synthesized light then passes through polarizer 106, whereby its measuring light component and reference light component interfere with each other at a phase corresponding to the angle of polarizer 106. This interfering light then changes the angle of polarizer 106, and multiple images are captured by imaging device 102. Based on the obtained brightness image data, a three-dimensional measurement of workpiece 110 is performed.

[0012] Existing technical documents

[0013] Patent documents

[0014] Patent document 1: Japanese Patent No. 6271493. Summary of the Invention

[0015] The problem that the invention aims to solve

[0016] In the three-dimensional measurement device described in Patent Document 1, by using optical components such as a polarization beam splitter and a quarter-wave plate, two kinds of light with different wavelengths are separated and converted into polarized light components (P-polarized light and S-polarized light) with different polarization directions, and two kinds of light traveling in the same direction on the same optical path can be separated.

[0017] For example, in Patent Document 1, a quarter-wavelength plate (quarter-wavelength plates 21, 22, etc. in the interference optical system 3 of Patent Document 1) is configured to make the S-polarized light component (or P-polarized light component) involved in the first light with a wavelength of 1500 nm and the P-polarized light component (or S-polarized light component) involved in the second light with a wavelength of 1503 nm the same, and the plates pass in the same direction.

[0018] However, the optical components required for separating and converting polarized light components (P-polarized light and S-polarized light), such as polarization beam splitters and quarter-wave plates, are difficult to manufacture with high precision, and their manufacturing errors may have a significant impact on the accuracy of polarization component separation and conversion.

[0019] In particular, it is very difficult to manufacture quarter-wave plates corresponding to two wavelengths with high precision. Therefore, as in Patent Document 1, when quarter-wave plates (quarter-wave plates 21, 22, etc. in Patent Document 1) are arranged at the positions where two different wavelengths of light pass, at least one of the two types of light passing through these positions may produce a conversion error.

[0020] A quarter-wave plate is an optical component that converts linearly polarized light into circularly polarized light or vice versa by imparting a phase difference of 1 / 4 wavelength (e.g., 375 nm or 375.75 nm) to incident light with a specified wavelength (e.g., 1500 nm or 1503 nm).

[0021] That is, in the case of manufacturing a 1 / 4 wavelength plate corresponding to a first light with a wavelength of 1500 nm and a second light with a wavelength of 1503 nm, a 1 / 4 wavelength plate is manufactured to impart a desired phase difference (e.g., 375.6 nm) in the range of 375 nm to 375.75 nm.

[0022] Therefore, as in Patent Document 1, in a structure that converts a polarized light component from S-polarized light to P-polarized light or from P-polarized light to S-polarized light by making a quarter-wave plate go back and forth, it is possible that the polarized light component is not completely converted and a slightly residual polarized light component (e.g., S-polarized light) from before the conversion is mixed in with the polarized light component (e.g., P-polarized light).

[0023] In this case, such as Figure 16 As shown, the incompletely converted polarized light components, as returning light Kp and Ks, are reflected or transmitted at the boundary surface 100e of the polarization beam splitter 100, and are guided in a direction different from the original direction.

[0024] Therefore, in the structure described in Patent Document 1, which uses different cameras to separately capture the interference light of the measurement light (S-polarized light) and the reference light (P-polarized light) involved in the first light, as well as the interference light of the measurement light (P-polarized light) and the reference light (S-polarized light) involved in the second light, the return light of the second light (or the first light) is incident on the first camera (or the second camera) that originally only captured the interference light involved in the first light (or the second light), resulting in the interference light containing the return light being captured, which may reduce the measurement accuracy.

[0025] The present invention was made in view of the above circumstances, and its object is to provide a three-dimensional measuring device that can achieve improvements in measurement accuracy, etc.

[0026] Methods for solving problems

[0027] The following sections describe the various methods suitable for solving the aforementioned problems. Furthermore, specific technical effects may be added to the corresponding technical solutions as needed.

[0028] Solution 1. A three-dimensional measuring device, characterized in that it comprises:

[0029] A specified optical system (specific optical system) has an optical unit (e.g., beam splitter, half-transparent and half-reflective mirror, etc.) capable of splitting a specified incident light into two beams, wherein the optical system is capable of illuminating an object under test with at least a portion of the split beam as a measurement beam and illuminating a reference surface with at least a portion of the other beam as a reference beam, and combining and emitting at least a portion of the measurement beam reflected by the object under test and at least a portion of the reference beam reflected by the reference surface;

[0030] The first irradiation unit is capable of emitting a first wavelength of light incident on the first input portion of the optical unit;

[0031] The second irradiation unit is capable of emitting a second wavelength of light that is incident on the second input section of the optical unit;

[0032] The first imaging unit is capable of capturing a predetermined output light related to the first light emitted from the first output section of the optical unit by the first light incident on the first input section;

[0033] The second imaging unit is capable of capturing a predetermined output light relating to the second light emitted from the second output unit of the optical unit by the second light incident onto the second input unit; and

[0034] An image processing unit is capable of performing a three-dimensional measurement of the object under test based on image data acquired by the first and second imaging units.

[0035] The measurement light involved in the first light from the optical unit towards the object under test and the measurement light involved in the second light from the optical unit towards the object under test have different travel directions (vectors), and the reference light involved in the first light from the optical unit towards the reference surface and the reference light involved in the second light from the optical unit towards the reference surface have different travel directions (vectors).

[0036] The measurement light involved in the first light reflected from the object under test and directed toward the optical unit has a different direction of travel (vector) than the measurement light involved in the second light reflected from the object under test and directed toward the optical unit. Furthermore, the reference light involved in the first light reflected from the reference surface and directed toward the optical unit has a different direction of travel (vector) than the reference light involved in the second light reflected from the reference surface and directed toward the optical unit.

[0037] The optical unit is configured to combine a portion of the measurement light involved in the first light reflected by the object under test and a portion of the reference light involved in the first light reflected by the reference surface and emit them from the first output unit, and to combine a portion of the measurement light involved in the second light reflected by the object under test and a portion of the reference light involved in the second light reflected by the reference surface and emit them from the second output unit.

[0038] According to Scheme 1 above, the configuration is such that there is no interval in which the travel directions (vectors) of the first and second rays from the illumination unit to the imaging unit overlap. That is, the first and second rays incident on the prescribed optical system do not interfere with each other and are emitted separately from the prescribed optical system in a completely separate state. Furthermore, even in the case of opposite travel directions and overlapping light paths, or in the case of light path intersection, no particular problem will occur.

[0039] Thus, according to this scheme, by simply setting the incident positions and incident angles of the first and second beams for the optical system, the first and second beams can be completely separated and processed. This significantly reduces the number of optical components required for the separation and conversion of polarized light components (P-polarized and S-polarized light), such as polarizing beam splitters and quarter-wave plates, thereby simplifying the structure. In particular, it enables an optical system that eliminates the need for a quarter-wave plate, which allows polarized light components of two different wavelengths to pass in the same direction along the same optical path.

[0040] As a result, the effects of manufacturing errors and other factors from the specified optical components, such as the aforementioned return light influence, can be eliminated, thereby improving measurement accuracy.

[0041] Furthermore, by using two lights with similar wavelengths as the first and second lights, the measurement range involved in three-dimensional measurement can be further expanded. In addition, since the output light involved in the first light and the output light involved in the second light can be captured simultaneously, the measurement efficiency can be improved.

[0042] Solution 2. The three-dimensional measuring device according to Solution 1, characterized in that it comprises:

[0043] A first polarizing plate is disposed between the optical unit and the reference plane to allow first polarized light (e.g., P-polarized light) to pass through;

[0044] A second polarizing plate is disposed between the optical unit and the object under test, allowing second polarized light (e.g., S-polarized light) to pass through;

[0045] A first quarter-wavelength plate, disposed between the first output section of the optical unit and the first imaging unit, converts the first polarized light and the second polarized light involved in the first light into circularly polarized light, respectively.

[0046] A second 1 / 4 wavelength plate, disposed between the second output section of the optical unit and the second imaging unit, converts the first polarized light and the second polarized light involved in the second light into circularly polarized light, respectively.

[0047] According to Scheme 2 above, three-dimensional measurement using the phase-shifting method can be performed, which can further improve the measurement accuracy.

[0048] Furthermore, here, a dedicated quarter-wavelength plate manufactured to match the first wavelength of the first light can be used as the "first quarter-wavelength plate," and a dedicated quarter-wavelength plate manufactured to match the second wavelength of the second light can be used as the "second quarter-wavelength plate." Therefore, compared to using quarter-wavelength plates corresponding to both wavelengths, the light conversion error can be reduced. As a result, improved measurement accuracy can be achieved.

[0049] Option 3. The three-dimensional measuring device according to Option 1 or 2, characterized in that,

[0050] When viewed from a predetermined axis (e.g., the Z-axis) orthogonal to the object under test, the optical paths of the first light beam from the optical unit toward the object under test and the optical paths of the second light beam from the optical unit toward the object under test are symmetrical about this axis.

[0051] and,

[0052] When viewed from a predetermined axis (e.g., the X-axis) orthogonal to the reference plane, the optical paths of the reference light involving the first light from the optical unit toward the reference plane and the optical paths of the reference light involving the second light from the optical unit toward the reference plane are symmetrical about this axis.

[0053] According to Scheme 3 above, compared to situations where the optical paths of the first and second beams of the measurement light overlap when viewed from a predetermined axial direction orthogonal to the object under test, the first and second beams of the measurement light moving from the optical unit toward the object under test are less likely to mix. Similarly, the first and second beams of the reference light moving from the optical unit toward the reference surface are also less likely to mix. As a result, measurement accuracy can be further improved.

[0054] Option 4. The three-dimensional measuring device according to any one of Options 1 to 3, characterized in that,

[0055] The angle of incidence of the first light relative to the object under test and the angle of incidence of the second light relative to the object under test are the same.

[0056] and,

[0057] The angle of incidence of the reference light of the first light relative to the reference surface and the angle of incidence of the reference light of the second light relative to the reference surface are the same.

[0058] According to scheme 4 above, the optical path length of the first light and the optical path length of the second light can be made the same. As a result, in both the imaging process involving the first light and the imaging process involving the second light, the object under test can be photographed at the same size (same magnification). Furthermore, the measurement accuracy can be improved.

[0059] Option 5. The three-dimensional measuring device according to any one of Options 1 to 4, characterized in that the optical unit is a semi-transparent and semi-reflective mirror.

[0060] According to Scheme 5 above, compared with thick-walled optical units such as beam splitters, thin-plate semi-transparent and semi-reflective mirrors can almost disregard light refraction, thus enabling the three-dimensional measurement device to be miniaturized.

[0061] For example, such as Figure 15 As shown in (a), when using a semi-transparent mirror 200 as the optical unit, the lower limit of the incident angle θ of light relative to the object under test 201 can be defined by the following equation (1).

[0062]

[0063] Here, "WD" is the diameter (width) of the laser emitted from the light source 203 and reflected by the object under test 201 before entering the imaging element 204. "WD" is the minimum distance between the light source 203 (imaging element 204) and the object under test 201 that must be ensured so that the positions of the light source 203 and the imaging element 204 do not overlap.

[0064] In contrast, such as Figure 15 As shown in (b), when using beam splitter 210 as the optical unit, the refraction of light in beam splitter 210 must be taken into account, so the above equation (1) cannot be applied. Assuming that, similar to the case of using semi-transparent mirror 200, if the light is to be incident on the object under test 201 at an incident angle θ, if the distance WE between the light source 203 (image element 204) and the object under test 201 is not set to be longer than the distance WD when using semi-transparent mirror 200, the positions of the light source 203 and the image element 204 will overlap.

[0065] Solution 6. The three-dimensional measuring device according to Solution 1 is characterized in that it is configured to perform three-dimensional measurement of the object under test by Fourier transform of the complex amplitude of the measuring light based on the image data (interference fringe image), wherein the image data is obtained by photographing carrier fringes generated by making the optical unit and the reference plane in a predetermined positional relationship.

[0066] Furthermore, "arranging the optical unit and the reference plane in a predetermined positional relationship" includes, for example, "tilting the reference plane from a predetermined reference posture." The "reference posture" may include, for example, a posture in which the "reference plane" is orthogonal to the second axis (e.g., the X-axis) when the "optical unit (e.g., a beam splitter, a semi-transparent mirror, etc.)" is arranged at a 45° angle relative to a first axis (e.g., the Z-axis) orthogonal to the object under test and a second axis (e.g., the X-axis) orthogonal to the first axis (e.g., the Z-axis).

[0067] According to Scheme 6 above, the polarization beam splitter, needless to say, can completely omit the optical components used in Scheme 2, such as the quarter-wave plate and polarizing plate, for separating and converting polarized light components (P-polarized light and S-polarized light). Furthermore, the imaging element of the imaging unit does not need to use a polarization image sensor.

[0068] As a result, it is possible to reduce the number of parts and simplify the structure. Furthermore, it is possible to reduce the impact of manufacturing errors from optical components, thereby improving measurement accuracy. Attached Figure Description

[0069] Figure 1 This is a simplified structural diagram of the three-dimensional measuring device according to the first embodiment.

[0070] Figure 2 This is a block diagram showing the electrical structure of a three-dimensional measuring device.

[0071] Figure 3 This is a light path diagram showing the light path of the first ray.

[0072] Figure 4 This is a light path diagram showing the light path of the second light.

[0073] Figure 5 This is a simplified structural diagram of a polarization image sensor.

[0074] Figure 6 This is a simplified structural diagram of the three-dimensional measuring device according to the second embodiment.

[0075] Figure 7 This is a simplified structural diagram of the three-dimensional measuring device according to the third embodiment.

[0076] Figure 8 This is a simplified structural diagram of the three-dimensional measuring device according to the fourth embodiment.

[0077] Figure 9 This is a simplified structural diagram of the three-dimensional measuring device according to the fifth embodiment.

[0078] Figure 10 of (a), Figure 10 (b) is a schematic diagram illustrating the angle of incidence of the first light relative to the reference plane and the setting part when the objective lens is configured.

[0079] Figure 11 This is a simplified structural diagram of the three-dimensional measuring device according to the sixth embodiment.

[0080] Figure 12 This is a simplified structural diagram of the three-dimensional measuring device according to the seventh embodiment.

[0081] Figure 13 This is an example optical path diagram showing a case where the travel directions of the measurement and reference beams involved in the first beam overlap with those of the measurement and reference beams involved in the second beam.

[0082] Figure 14 (a) is a schematic diagram showing the arrangement of the first position where the incident light of the first light is incident and the second position where the emitted light of the first light is emitted in a direction parallel to one side of the first surface of the beam splitter. Figure 14 (b) is a schematic diagram showing the arrangement of the first position of the incident light of the first light and the second position of the emitted light of the first light in the diagonal direction of the first surface of the beam splitter.

[0083] Figure 15(a) is a schematic diagram illustrating the light path of the incident and reflected light of the test object when a semi-transparent and semi-reflective mirror is used; Figure 15 (b) is a schematic diagram illustrating the optical paths of the incident and reflected light of the object under test when a beam splitter is used.

[0084] Figure 16 This is a light path diagram showing the light path in a conventional three-dimensional measurement device. Detailed Implementation

[0085] [First Implementation Method]

[0086] Hereinafter, one embodiment of the three-dimensional measuring device will be described with reference to the accompanying drawings. Figure 1 This is a schematic diagram showing a simplified structure of the three-dimensional measuring device 1 according to this embodiment. Figure 2 This is a block diagram showing the electrical structure of the three-dimensional measuring device 1. Hereinafter, for convenience, [the following will be described as follows]. Figure 1 The left-right direction of the paper is set as the "X-axis direction", the front-back direction of the paper is set as the "Y-axis direction", and the top-bottom direction of the paper is set as the "Z-axis direction" for explanation.

[0087] The three-dimensional measuring device 1 is constructed based on the principle of an interferometer and includes: two light projection systems 2A and 2B (first light projection system 2A and second light projection system 2B), which can output light of a specific wavelength; an interferometric optical system 3, which receives light emitted from the light projection systems 2A and 2B respectively; two imaging systems 4A and 4B (first imaging system 4A and second imaging system 4B), which can capture light emitted from the interferometric optical system 3; and a control device 5 (see reference). Figure 2 This involves various control, image processing, and computational processing processes related to the projection systems 2A and 2B, the interference optical system 3, and the imaging systems 4A and 4B.

[0088] Here, "control device 5" constitutes the "image processing unit" in this embodiment, and "interference optical system 3" constitutes the "prescribed optical system (specific optical system)" in this embodiment. Furthermore, in this embodiment, an optical system that splits a predetermined incident light into two beams (measurement beam and reference beam) for the purpose of generating light interference (capturing interference light), creates an optical path difference between the two beams, and then recombines and outputs the result is called an "interference optical system." That is, an optical system that does not cause internal interference between the two beams but only outputs the combined beam is also called an "interference optical system." Therefore, as in this embodiment, when the two beams (measurement beam and reference beam) do not interfere and are output as the combined beam from the "interference optical system," as described later, in at least the stage before capturing the image, the light is converted into interference light via a predetermined interference unit.

[0089] First, the structures of the two projection systems 2A and 2B (first projection system 2A and second projection system 2B) will be described in detail. The first projection system 2A includes a first light-emitting part 11A, a first light isolator 12A, etc. Here, the "first light-emitting part 11A" constitutes the "first illumination unit" in this embodiment.

[0090] Although the illustration is omitted, the first light-emitting unit 11A includes a laser source capable of outputting linearly polarized light of a specific wavelength λ1, a beam expander that amplifies the linearly polarized light output from the laser source and emits it as parallel light, a polarizing plate for intensity adjustment, and a half-wavelength plate for adjusting the polarization direction.

[0091] In this embodiment, the optical axis (light emission direction) JA1 of the first light-emitting unit 11A is tilted to the right by an angle θ1 relative to the Z-axis direction. In this structure, linearly polarized light with a wavelength λ1 (e.g., λ1 = 1500 nm) is emitted from the first light-emitting unit 11A into the interference optical system 3. This linearly polarized light has a polarization direction tilted at 45° relative to both the X-axis and Y-axis directions. Here, "wavelength λ1" corresponds to the "first wavelength" in this embodiment. Hereinafter, the light with a wavelength λ1 emitted from the first light-emitting unit 11A will be referred to as "first light."

[0092] The first optical isolator 12A is an optical element that allows light traveling in only one direction (in this embodiment, the interference optical system 3 side) to pass through while blocking light traveling in the opposite direction (in this embodiment, the first light-emitting part 11A side). As a result, by allowing only the first light emitted from the first light-emitting part 11A to pass through, damage or instability of the first light-emitting part 11A caused by incident light can be prevented.

[0093] Furthermore, in this embodiment, it will be with Figure 1 Linearly polarized light, whose polarization direction is parallel to the plane of the paper (XZ plane), is called P-polarized light (P-polarized component). Figure 1 Linearly polarized light, with the Y-axis direction perpendicular to the plane of the paper as its polarization direction, is called S-polarized light (S-polarized light component).

[0094] The second projection system 2B, like the first projection system 2A described above, includes a second light-emitting part 11B, a second light isolator 12B, etc. Here, the "second light-emitting part 11B" constitutes the "second illumination unit" in this embodiment.

[0095] The second light-emitting part 11B, like the first light-emitting part 11A, includes a laser source capable of outputting linearly polarized light of a specific wavelength λ2, a beam expander that amplifies the linearly polarized light output from the laser source and emits it as parallel light, a polarizing plate for intensity adjustment, and a half-wavelength plate for adjusting the polarization direction.

[0096] In this embodiment, the optical axis (light emission direction) JB1 of the second light-emitting part 11B is tilted upwards by an angle θ2 relative to the X-axis direction. Furthermore, in this embodiment, the angle θ2 is set to the same angle as the aforementioned angle θ1.

[0097] In this structure, in this embodiment, linearly polarized light with a wavelength of λ2 (e.g., λ2 = 1503 nm) is emitted from the second light-emitting unit 11B into the interference optical system 3. The linearly polarized light has a polarization direction that is tilted at 45° relative to the X-axis and Y-axis directions. Here, "wavelength λ2" is equivalent to "second wavelength" in this embodiment. Hereinafter, the light with a wavelength of λ2 emitted from the second light-emitting unit 11B will be referred to as "second light".

[0098] Like the first optical isolator 12A, the second optical isolator 12B is an optical element that allows light traveling in only one direction (in this embodiment, the interference optical system 3 side) to pass through while blocking light traveling in the opposite direction (in this embodiment, the second light-emitting part 11B side). Thus, by allowing only the second light emitted from the second light-emitting part 11B to pass through, damage and instability of the second light-emitting part 11B caused by incident light can be prevented.

[0099] Next, the structure of the interference optical system 3 will be described in detail. The interference optical system 3 includes a semi-transparent mirror HM, polarizing plates 21 and 22, a reference plane 23, and a mounting section 24.

[0100] A transflective mirror (HM) is a known thin-plate optical component that splits incident light into transmitted and reflected light at a predetermined ratio (1:1 in this embodiment), including polarization states, and constitutes the optical unit in this embodiment. Thus, the P-polarized and S-polarized components of the transmitted light, as well as the P-polarized and S-polarized components of the reflected light, are all split at the same ratio, and the polarization states of the transmitted and reflected light are the same as those of the incident light.

[0101] The translucent mirror HM is arranged such that its front and back surfaces are parallel to the Y-axis and tilted at 45° relative to the X-axis and Z-axis. Hereinafter, in this embodiment, the upper surface of the translucent mirror HM into which the first light emitted from the first light-emitting system 2A (first light-emitting unit 11A) is incident is referred to as the "first surface HMa", and the lower surface of the translucent mirror HM into which the second light emitted from the second light-emitting system 2B (second light-emitting unit 11B) is referred to as the "second surface HMb".

[0102] Furthermore, in the interference optical system 3, a polarizer 21 is arranged opposite to the first surface HMa of the semi-transparent mirror HM in the X-axis direction, and a reference surface 23 is arranged opposite to the polarizer 21 in the X-axis direction. Moreover, the polarizer 21 and the reference surface 23 are arranged orthogonally to the X-axis direction (so that the X-axis direction is the normal direction).

[0103] In this embodiment, the polarizer 21 is configured to allow only P-polarized light, which is the first polarized light, to pass through, while blocking S-polarized light. That is, only the P-polarized component of the light emitted from the first surface HMa of the semi-transparent mirror HM passes through the polarizer 21 and illuminates the reference surface 23 as reference light. Furthermore, the reference light (P-polarized light) reflected by the reference surface 23 passes through the polarizer 21 again and enters the first surface HMa of the semi-transparent mirror HM. The "polarizer 21" constitutes the "first polarizer" in this embodiment.

[0104] Furthermore, in the interference optical system 3, a polarizer 22 is arranged opposite to the second surface HMb of the semi-transparent mirror HM in the Z-axis direction, and a mounting section 24 is arranged opposite to the polarizer 22 in the Z-axis direction. Moreover, the polarizer 22 and the mounting section 24 are arranged orthogonally to the Z-axis direction (so that the Z-axis direction is the normal direction).

[0105] In this embodiment, the polarizer 22 is configured to allow only S-polarized light, which is the second polarized light, to pass through, while blocking P-polarized light. That is, only the S-polarized component of the light emitted from the second surface HMb of the semi-transparent mirror HM passes through the polarizer 22 and is used as measurement light to illuminate the workpiece W placed in the mounting section 24; the workpiece W is the object to be measured. Furthermore, the measurement light (S-polarized light) reflected by the workpiece W passes through the polarizer 22 again and is incident on the second surface HMb of the semi-transparent mirror HM. The "polarizer 22" constitutes the "second polarizer" in this embodiment.

[0106] Next, the structure of the two shooting systems 4A and 4B (the first shooting system 4A and the second shooting system 4B) will be described in detail.

[0107] The first imaging system 4A includes a 1 / 4 wavelength plate 31A, a first camera 33A, etc. Here, the "first camera 33A" constitutes the "first imaging unit" in this embodiment.

[0108] The quarter-wave plate 31A is used to convert the reference light component (P-polarized light component) and the measurement light component (S-polarized light component) of the first light emitted from the first surface HMa of the semi-transparent mirror HM into circularly polarized light, thus constituting the "first quarter-wave plate" in this embodiment. Furthermore, the quarter-wave plate 31A is a quarter-wave plate specifically designed to match the wavelength λ1 of the first light (e.g., λ1 = 1500 nm).

[0109] The first camera 33A in this embodiment is a polarized light camera equipped with a polarized image sensor 70A as the imaging element. In this embodiment, the optical axis (incident direction of the composite light involved in the first light) JA2 of the first camera 33A is tilted to the left by an angle θ1 relative to the Z-axis direction.

[0110] like Figure 5 As shown, the polarization image sensor 70A includes a light-receiving element array 71 that forms the main body of the sensor, a polarizer array 72 disposed on the front side that forms its light-receiving surface, and a microlens array 73 disposed on its front side.

[0111] The light-receiving element array 71 has a general semiconductor element structure such as a CCD image sensor, which is composed of multiple light-receiving elements (pixels) 74 arranged in a matrix in two dimensions.

[0112] Furthermore, the actual light-receiving element array 71 is an element arranged with multiple pixels (e.g., 1280×1024 pixels), but... Figure 5 For the sake of simplicity, only the 4 rows and 4 columns that are part of it are shown in the illustration (the same applies to the polarizer array 72 and the microlens array 73).

[0113] The polarizer array 72 is an element in which multiple polarizers 75 are arranged in a two-dimensional matrix. Each polarizer 75 is arranged in a one-to-one correspondence with each light-receiving element 74 in the light-receiving element array 71.

[0114] Polarizer 75 selectively transmits the reference light component and the measurement light component, which have been converted into circularly polarized light as described above. This allows interference between the reference light component and the measurement light component, which have different rotation directions. Furthermore, a predetermined phase difference is assigned to the reference light component and the measurement light component. Therefore, each polarizer 75 can also constitute a "phase-shifting unit" or "interference unit" in this embodiment.

[0115] The polarizer 75 is composed of four polarizers 75a, 75b, 75c, and 75d, each with a transmission axis setting angle that differs by 45°. More specifically, it includes: a first polarizer 75a, which is set to have a transmission axis setting angle of "0°" relative to a reference line (horizontal line); a second polarizer 75b, which is set to have a transmission axis setting angle of "45°"; a third polarizer 75c, which is set to have a transmission axis setting angle of "90°"; and a fourth polarizer 75d, which is set to have a transmission axis setting angle of "135°".

[0116] Therefore, the reference light component and the measurement light component of the light passing through each polarizer 75 of the polarizer array 72 can interfere with each other with four sets of phase differences. That is, it is possible to generate four sets of interference light with each of the reference light and the measurement light having a phase difference of 90°.

[0117] As a specific setting, the phase shift of the reference light component of the light transmitted through the first polarizer 75a is "0°", the phase shift of the reference light component of the light transmitted through the second polarizer 75b is "90°", the phase shift of the reference light component of the light transmitted through the third polarizer 75c is "180°", and the phase shift of the reference light component of the light transmitted through the fourth polarizer 75d is "270°".

[0118] Furthermore, the polarizer array 72 is configured with a specific polarizer arrangement pattern (see reference). Figure 5 The structure of the thick frame portion is arranged in a matrix, and the specific polarizer arrangement pattern is formed by arranging the four polarizers 75a, 75b, 75c, and 75d with different transmission axis angles in a matrix of 2 rows and 2 columns in a prescribed order.

[0119] In this embodiment, the polarizer arrangement pattern is configured such that, when viewed from the front of the polarizer array 72, a first polarizer 75a is arranged in the lower right, a second polarizer 75b is arranged in the upper right, a third polarizer 75c is arranged in the upper left, and a fourth polarizer 75d is arranged in the lower left.

[0120] Therefore, regardless of where the four polarizers 75 arranged in a matrix of 2 rows and 2 columns are extracted from the polarizer array 72, it will necessarily include each of the four polarizers 75a, 75b, 75c, and 75d with different transmission axis angles.

[0121] The microlens array 73 is composed of multiple microlenses 76 arranged in a matrix in two dimensions. The microlenses 76 are used to improve the light-gathering efficiency of each pixel and are arranged in a one-to-one correspondence with each polarizer 75 of the polarizer array 72.

[0122] Thus, the light focused by each microlens 76 of the microlens array 73 passes through each polarizer 75 of the corresponding polarizer array 72, thereby assigning a predetermined phase difference to its reference light component and measurement light component, and becoming interference light, which is received by each light-receiving element 74 of the corresponding light-receiving element array 71.

[0123] The brightness image data captured and acquired by the first camera 33A is converted into a digital signal inside the first camera 33A and then input to the control device 5 (image data storage device 54) in the form of a digital signal.

[0124] Like the first shooting system 4A, the second shooting system 4B includes a quarter-wave plate 31B, a second camera 33B, etc. Here, the "second camera 33B" constitutes the "second shooting unit" in this embodiment.

[0125] The quarter-wave plate 31B is used to convert the reference light component (P-polarized light component) and the measurement light component (S-polarized light component) of the second light emitted from the second surface HMb of the semi-transparent mirror HM into circularly polarized light, thus constituting the "second quarter-wave plate" in this embodiment. Furthermore, the quarter-wave plate 31B is a quarter-wave plate specifically designed to match the wavelength λ2 of the second light (e.g., λ2 = 1503 nm).

[0126] The second camera 33B in this embodiment, like the first camera 33A, is a polarized light camera equipped with a polarization image sensor 70B as its imaging element. In this embodiment, the optical axis (incident direction of the synthesized light involved in the second light) JB2 of the second camera 33B is tilted downwards by an angle θ2 relative to the X-axis direction. Furthermore, the polarization image sensor 70B has the same structure as the polarization image sensor 70A described above in the first camera 33A, therefore its detailed description is omitted.

[0127] Similar to the first camera 33A, the brightness image data captured and acquired by the second camera 33B is converted into a digital signal inside the second camera 33B and then input to the control device 5 (image data storage device 54) in the form of a digital signal.

[0128] Here, the electrical structure of control device 5 will be described. For example... Figure 2 As shown, the control device 5 includes: a microcomputer 51, which performs overall control of the three-dimensional measuring device 1; an input device 52, which serves as an "input unit" consisting of a keyboard, mouse, or touch panel; a display device 53, which serves as a "display unit" displaying images such as liquid crystal displays; an image data storage device 54, which sequentially stores brightness image data captured and acquired by cameras 33A and 33B; a calculation result storage device 55, which stores various calculation results; and a setting data storage device 56, which pre-stores various information.

[0129] In addition, the microcomputer 51 includes a CPU 51a as an arithmetic unit, a ROM 51b for storing various programs, and a RAM 51c for temporarily storing various data such as arithmetic data and input / output data, and is electrically connected to the aforementioned devices 52 to 56.

[0130] Next, the function of the three-dimensional measuring device 1 will be explained. Furthermore, as will be described later, in this embodiment, the first light and the second light are irradiated simultaneously, and the optical paths of the first light and the second light partially overlap. However, for easier understanding, different accompanying drawings will be used to explain each optical path of the first light and the second light separately.

[0131] First, refer to Figure 3 The optical path of the first ray is explained. For example... Figure 3As shown, a first light with a wavelength of λ1 (linearly polarized light whose polarization direction is tilted at 45° relative to the X-axis and Y-axis directions) is emitted from the first light projection system 2A (first light-emitting part 11A) toward the interference optical system 3. Here, the direction of travel (vector) of the light is tilted at the aforementioned angle θ1 relative to the Z-axis direction.

[0132] The first light emitted from the first projection system 2A is incident on the first position P1 of the semi-transparent mirror HM. Therefore, the "first position P1 of the semi-transparent mirror HM" constitutes the "first input unit" in this embodiment.

[0133] For the first light incident on the first position P1 of the semi-transparent mirror HM, a portion (half) of it is reflected by the first surface HMa and emitted toward the polarizer 21, while the remaining portion (half) passes through the semi-transparent mirror HM and is emitted from the second surface HMb toward the polarizer 22.

[0134] The first light reflected by the first surface HMa of the semi-transparent mirror HM is incident on the polarizer 21, with only its P-polarized component passing through the polarizer 21. The P-polarized component of the first light that has passed through the polarizer 21 serves as a reference light and illuminates and is reflected by the reference surface 23. Here, the angle of incidence and the angle of reflection of the reference light (P-polarized light) related to the first light relative to the reference surface 23 are the aforementioned angles θ1.

[0135] Subsequently, the reference light (P-polarized light) involved in the first light reflected by the reference surface 23 passes through the polarizer 21 again and is incident on the second position P2 of the semi-transparent mirror HM. For the reference light involved in the first light incident on the second position P2 of the semi-transparent mirror HM, a portion (half) is reflected by the first surface HMa and emitted toward the first imaging system 4A, while the remaining portion (half) passes through the semi-transparent mirror HM and is emitted from the second surface HMb toward the second projection system 2B.

[0136] On the other hand, the first light incident from the first projection system 2A onto the first position P1 of the semi-transparent mirror HM, and passing through the semi-transparent mirror HM, is incident on the polarizer 22, with only its S-polarized component passing through the polarizer 22. The S-polarized component of the first light passing through the polarizer 22 is used as measurement light to illuminate the workpiece W and is reflected. Here, the angle of incidence and the angle of reflection of the measurement light related to the first light relative to the setting unit 24 (workpiece W) are the aforementioned angle θ1.

[0137] Subsequently, the measurement light (S-polarized light) involved in the first light reflected by the workpiece W passes through the polarizer 22 again and is incident on the second position P2 of the semi-transparent mirror HM. For the measurement light involved in the first light incident on the second position P2 of the semi-transparent mirror HM, a portion (half) passes through the semi-transparent mirror HM and is emitted from the first surface HMa toward the first imaging system 4A, while the remaining portion (half) is reflected by the second surface HMb and is emitted toward the second projection system 2B.

[0138] That is, at the second position P2 of the semi-transparent mirror HM, a reference light (P-polarized light) involving the first light reflected by the first surface HMa and a measurement light (S-polarized light) involving the first light transmitted to the first surface HMa are synthesized, and a reference light (P-polarized light) involving the first light transmitted to the second surface HMb and a measurement light (S-polarized light) involving the first light reflected by the second surface HMb are synthesized.

[0139] As a result, the composite light, which combines the reference light (P-polarized light) and the measurement light (S-polarized light) involved in the first light, is emitted as the output light from the second position P2 of the semi-transparent mirror HM to the first imaging system 4A and the second projection system 2B, respectively. Therefore, the "second position P2 of the semi-transparent mirror HM" constitutes the "first output unit" in this embodiment.

[0140] Among them, the composite light (reference light and measurement light) involved in the first light incident on the second projection system 2B is interrupted by the second optical isolator 12B and becomes discarded light.

[0141] On the other hand, the first light incident on the first imaging system 4A involves a composite light (reference light and measurement light). The measurement light component (S-polarized light component) is first converted into left-handed circularly polarized light by a quarter-wave plate 31A, while the reference light component (P-polarized light component) is converted into right-handed circularly polarized light. Here, the left-handed and right-handed circularly polarized light do not interfere with each other due to their different rotation directions.

[0142] The synthesized light involved in the first light is then incident on the first camera 33A (polarization image sensor 70A), passing through the polarizer array 72, whereby its reference light component and measurement light component interfere with each other in phase corresponding to the transmission axis angles of various polarizers 75a, 75b, 75c, and 75d. Furthermore, the interference light involved in the first light is captured by the first camera 33A (light-receiving element array 71).

[0143] Specifically, the interference light involved in the first light, which imparts a phase difference of “0°” to the reference light component and the measurement light component in the first polarizer 75a, is received in the light-receiving element 74 corresponding to the first polarizer 75a.

[0144] Similarly, the interference light involving the first light, which imparts a "90°" phase difference between the reference light component and the measurement light component in the second polarizer 75b, is received in the light-receiving element 74 corresponding to the second polarizer 75b. The interference light involving the first light, which imparts a "180°" phase difference between the reference light component and the measurement light component in the third polarizer 75c, is received in the light-receiving element 74 corresponding to the fourth polarizer 75d. The interference light involving the first light, which imparts a "270°" phase difference between the reference light component and the measurement light component in the fourth polarizer 75d, is received in the light-receiving element 74 corresponding to the fourth polarizer 75d.

[0145] Next, refer to Figure 4 The optical path of the second ray will be explained. For example... Figure 4 As shown, a second light with a wavelength of λ2 (linearly polarized light whose polarization direction is tilted at 45° relative to the Y-axis and Z-axis directions) is emitted from the second light projection system 2B (second light-emitting part 11B) toward the interference optical system 3. Here, the direction of travel (vector) of the light is tilted at an angle θ2 (=θ1) relative to the X-axis direction.

[0146] The second light emitted from the second projection system 2B is incident on the second position P2 of the semi-transparent mirror HM. Therefore, the "second position P2 of the semi-transparent mirror HM" constitutes the "second input section" in this embodiment.

[0147] For the second light incident on the second position P2 of the semi-transparent and semi-reflective mirror HM, a portion (half) of it passes through the semi-transparent and semi-reflective mirror HM and is emitted toward the polarizer 21, while the remaining portion (half) is reflected by the second surface HMb and is emitted toward the polarizer 22.

[0148] The second light, passing through the second position P2 of the semi-transparent mirror HM, is incident on the polarizer 21, with only its P-polarized component passing through the polarizer 21. The P-polarized component of the second light that has passed through the polarizer 21 serves as a reference light and is reflected off the reference surface 23. Here, the incident angle and reflection angle of the reference light (P-polarized light) related to the second light relative to the reference surface 23 are the aforementioned angle θ2.

[0149] Subsequently, the reference light (P-polarized light) involved in the second light reflected by the reference surface 23 passes through the polarizer 21 again and is incident on the first position P1 of the semi-transparent mirror HM. For the reference light involved in the second light incident on the first position P1 of the semi-transparent mirror HM, a portion (half) passes through the semi-transparent mirror HM and is emitted from the second surface HMb toward the second imaging system 4B, while the remaining portion (half) is reflected by the first surface HMa and is emitted toward the first projection system 2A.

[0150] On the other hand, the second light incident from the second projection system 2B onto the second position P2 of the semi-transparent mirror HM, and reflected by the second surface HMb, is incident on the polarizer 22, with only its S-polarized component passing through the polarizer 22. The S-polarized component of the second light transmitted through the polarizer 22 is used as measurement light to illuminate the workpiece W and is reflected. Here, the angle of incidence and the angle of reflection of the measurement light related to the second light relative to the setting part 24 (workpiece W) are the aforementioned angle θ2.

[0151] Subsequently, the measurement light (S-polarized light) involved in the second light reflected by the workpiece W passes through the polarizer 22 again and is incident on the first position P1 of the semi-transparent mirror HM. For the measurement light involved in the second light incident on the first position P1 of the semi-transparent mirror HM, a portion (half) is reflected by the second surface HMb and emitted towards the second imaging system 4B, while the remaining portion (half) passes through the semi-transparent mirror HM and is emitted from the first surface HMa towards the first projection system 2A.

[0152] That is, at the first position P1 of the semi-transparent mirror HM, a reference light (P-polarized light) involving the second light reflected by the first surface HMa and a measurement light (S-polarized light) involving the second light transmitted to the first surface HMa are synthesized, and a reference light (P-polarized light) involving the second light transmitted to the second surface HMb and a measurement light (S-polarized light) involving the second light reflected by the second surface HMb are synthesized.

[0153] As a result, the composite light, which combines the reference light (P-polarized light) and the measurement light (S-polarized light) involved in the second light synthesis, is emitted as the output light from the first position P1 of the semi-transparent mirror HM to the second imaging system 4B and the first projection system 2A, respectively. Therefore, the "first position P1 of the semi-transparent mirror HM" constitutes the "second output unit" in this embodiment.

[0154] Among them, the composite light (reference light and measurement light) involved in the second light incident on the first projection system 2A is interrupted by the first optical isolator 12A and becomes discarded light.

[0155] On the other hand, the composite light (reference light and measurement light) involved in the second light incident on the second imaging system 4B first converts its measurement light component (S-polarized light component) into left-handed circularly polarized light and its reference light component (P-polarized light component) into right-handed circularly polarized light by passing through the quarter-wave plate 31B. Here, the left-handed and right-handed circularly polarized light do not interfere with each other because of their different rotation directions.

[0156] The synthesized light involved in the second beam is then incident on the second camera 33B (polarization image sensor 70B), passing through the polarizer array 72. Thereby, its reference light component and measurement light component interfere with each other in phase, corresponding to the transmission axis angles of the various polarizers 75a, 75b, 75c, and 75d. Furthermore, the interference light involved in the second beam is captured by the second camera 33B (light-receiving element array 71).

[0157] Specifically, in the light-receiving element 74 corresponding to the first polarizer 75a, interference light involving the second light that imparts a "0°" phase difference to the reference light component and the measurement light component in the first polarizer 75a is received.

[0158] Similarly, in the light-receiving element 74 corresponding to the second polarizer 75b, interference light involving the second light, which imparts a phase difference of "90°" to the reference light component and the measurement light component in the second polarizer 75b, is received. In the light-receiving element 74 corresponding to the third polarizer 75c, interference light involving the second light, which imparts a phase difference of "180°" to the reference light component and the measurement light component in the third polarizer 75c, is received. In the light-receiving element 74 corresponding to the fourth polarizer 75d, interference light involving the second light, which imparts a phase difference of "270°" to the reference light component and the measurement light component in the fourth polarizer 75d, is received.

[0159] Next, the steps of the shape measurement process performed by the control device 5 will be described in detail. First, after the workpiece W is placed in the setting unit 24, a first light is irradiated onto the interference optical system 3 (the first position P1 of the semi-transparent mirror HM) from the first light projection system 2A, and a second light is irradiated onto the interference optical system 3 (the second position P2 of the semi-transparent mirror HM) from the second light projection system 2B.

[0160] As a result, the composite light (reference light and measurement light) involving the first light is emitted from the interferometric optical system 3 (the second position P2 of the semi-transparent mirror HM) to the first imaging system 4A, while the composite light (reference light and measurement light) involving the second light is emitted from the interferometric optical system 3 (the first position P1 of the semi-transparent mirror HM) to the second imaging system 4B.

[0161] Next, while capturing the composite light involved in the first light using the first imaging system 4A, capturing the composite light involved in the second light using the second imaging system 4B. Then, the brightness image data acquired from each camera 33A and 33B is output to the control device 5. The control device 5 stores the input brightness image data in the image data storage device 54.

[0162] Thus, the brightness image data (brightness image data involving the first light and brightness image data involving the second light) obtained through one imaging process respectively contain four sets of brightness data (intensity data of four sets of interference lights with different phases) required for three-dimensional measurement.

[0163] Then, the control device 5 measures the surface shape of the workpiece W using a phase-shifting method based on the brightness image data of the first light and the brightness image data of the second light stored in the image data storage device 54. That is, it measures the height at each measurement position on the surface of the workpiece W. The measurement result (height data) of the workpiece W obtained in this way is stored in the calculation result storage device 55 of the control device 5. Furthermore, the measurement method based on the phase-shifting method using two light wavelengths as described above is known technology (for example, refer to Japanese Patent No. 6271493), so its detailed description is omitted.

[0164] As detailed above, in this embodiment, the first and second beams traveling from the projection systems 2A and 2B to the imaging systems 4A and 4B are configured such that their directions (vectors) do not overlap. That is, the first and second beams incident on the interference optical system 3 do not interfere with each other and are emitted separately from the interference optical system 3 in a completely separated state.

[0165] Thus, according to this embodiment, by simply setting the incident positions and incident angles of the first and second beams relative to the interference optical system 3, the first and second beams can be processed completely separately. This significantly reduces the number of optical components required for separating and converting polarized light components (P-polarized and S-polarized light), such as polarizing beam splitters and quarter-wave plates, thereby simplifying the structure. In particular, it enables an optical system that eliminates the need for a quarter-wave plate, which allows polarized light components of two different wavelengths to pass in the same direction along the same optical path.

[0166] As a result, the influence of manufacturing errors and other factors from the specified optical components can be eliminated, thereby improving measurement accuracy.

[0167] Furthermore, by using two lights with similar wavelengths as the first and second lights, the measurement range involved in three-dimensional measurement can be further expanded. In addition, since the output light involved in the first light and the output light involved in the second light can be captured simultaneously, the measurement efficiency can be improved.

[0168] Furthermore, in this embodiment, by using polarization image sensors 70A and 70B as imaging elements of cameras 33A and 33B, multiple brightness data points required for height measurement of workpiece W based on the phase-shift method can be acquired simultaneously through a single image captured by each camera 33A and 33B. As a result, structural simplification and reduced data acquisition time are achieved.

[0169] [Second Implementation]

[0170] The following is for reference. Figure 6 The second embodiment will be described. This embodiment differs from the first embodiment mainly in the configuration and structure of the imaging systems 4A and 4B. Therefore, in this embodiment, the features that differ from the first embodiment will be described in detail, while the same structural parts will be labeled with the same reference numerals, and detailed descriptions of these parts will be omitted.

[0171] The first imaging system 4A according to this embodiment is configured to capture the light emitted towards the second projection system 2B from the composite light of the first light emitted in both directions from the second position P2 of the semi-transparent mirror HM. Similarly, the second imaging system 4B according to this embodiment is configured to capture the light emitted towards the first projection system 2A from the composite light of the second light emitted in both directions from the first position P1 of the semi-transparent mirror HM. Detailed descriptions will follow.

[0172] In this embodiment, a first beam splitter 13A is provided between the second projection system 2B and the semi-transparent mirror HM, arranged in a manner that overlaps with the optical axis JB1 of the second light-emitting part 11B.

[0173] Furthermore, the first beam splitter 13A is a known cubic optical component that is bonded together with a right-angled prism (a triangular prism with a right-angled isosceles triangle as its base. The same applies below). A coating such as a metal film is applied to its bonding surface 13Ah.

[0174] Similarly, the beam splitter and the half-transparent, half-reflective mirror HM also include polarization states, splitting the incident light into transmitted light and reflected light at a predetermined ratio (1:1 in this embodiment). That is, the P-polarized and S-polarized components of the transmitted light and the P-polarized and S-polarized components of the reflected light are all split at the same ratio, and the polarization states of the transmitted light and reflected light are the same as those of the incident light.

[0175] The first beam splitter 13A is configured such that one of its two adjacent surfaces, sandwiching its bonding surface 13Ah, is orthogonal to the optical axis JB1 of the second light-emitting part 11B and the other is orthogonal to the optical axis JA2 of the first camera 33A. That is, the bonding surface 13Ah of the first beam splitter 13A is configured to be tilted at 45° relative to the optical axes JB1 and JA2.

[0176] Thus, a portion (half) of the composite light involved in the first light emitted from the second surface HMb of the second position P2 of the semi-transparent mirror HM can be transmitted to the second projection system 2B side via the first beam splitter 13A, while the remaining portion (half) is reflected to the first imaging system 4A side and incident.

[0177] Furthermore, in this embodiment, a second beam splitter 13B is provided between the first light projection system 2A and the semi-transparent mirror HM, arranged in a manner that overlaps with the optical axis JA1 of the first light-emitting part 11A.

[0178] Like the first beam splitter 13A, the second beam splitter 13B is a known cubic optical component that integrates right-angle prisms into one piece, with a coating such as a metal film applied to the bonding surface 13Bh.

[0179] The second beam splitter 13B is configured such that one of its two adjacent surfaces, sandwiching its mating surface 13Bh, is orthogonal to the optical axis JA1 of the first light-emitting part 11A and the other is orthogonal to the optical axis JB2 of the second camera 33B. That is, the mating surface 13Bh of the second beam splitter 13B is configured to be inclined at 45° relative to the optical axes JA1 and JB2.

[0180] Thus, via the second beam splitter 13B, a portion (half) of the composite light involved in the second light emitted from the first surface HMa of the first position P1 of the semi-transparent mirror HM can be transmitted to the first projection system 2A side, while the remaining portion (half) is reflected to the second imaging system 4B side and incident.

[0181] Next, the optical path of the first light according to this embodiment will be described. The first light emitted from the first projection system 2A is incident on the second beam splitter 13B.

[0182] A portion (half) of the first light incident on the second beam splitter 13B passes through the bonding surface 13Bh and is incident on the first position P1 of the semi-transparent mirror HM. On the other hand, the remaining portion (half) of the first light incident on the second beam splitter 13B is reflected by the bonding surface 13Bh and becomes discarded light.

[0183] Then, for the first light incident on the first position P1 of the semi-transparent mirror HM, a composite light that combines the reference light (P-polarized light) and the measurement light (S-polarized light) involved in the first light is emitted from the second position P2 of the semi-transparent mirror HM to the first beam splitter 13A along the same optical path as in the first embodiment described above.

[0184] A portion (half) of the composite light (reference light and measurement light) involved in the first beam splitter 13A is incident on the second projection system 2B through the bonding surface 13Ah, while the remaining portion (half) is reflected by the bonding surface 13Ah and incident on the first imaging system 4A.

[0185] In this system, the composite light (reference light and measurement light) involved in the first light incident on the second projection system 2B is interrupted by the second optical isolator 12B, becoming discarded light. On the other hand, in the composite light involved in the first light incident on the first imaging system 4A, the reference light component and the measurement light component are respectively converted into circularly polarized light and captured as interference light.

[0186] Next, the optical path of the second light according to this embodiment will be described. The second light emitted from the second projection system 2B is incident on the first beam splitter 13A.

[0187] A portion (half) of the second light incident on the first beam splitter 13A passes through the bonding surface 13Ah and is incident on the second position P2 of the semi-transparent mirror HM. On the other hand, the remaining portion (half) of the second light incident on the first beam splitter 13A is reflected by the bonding surface 13Ah and becomes discarded light.

[0188] Then, for the second light incident on the second position P2 of the semi-transparent mirror HM, along the same optical path as the first embodiment described above, a composite light consisting of the reference light (P-polarized light) and the measurement light (S-polarized light) involved in the second light is emitted from the first position P1 of the semi-transparent mirror HM to the second beam splitter 13B.

[0189] A portion (half) of the composite light (reference light and measurement light) involved in the second beam splitter 13B is incident on the first projection system 2A through the bonding surface 13Bh, while the remaining portion (half) is reflected by the bonding surface 13Bh and incident on the second imaging system 4B.

[0190] In this system, the composite light (reference light and measurement light) involved in the second light incident on the first projection system 2A is interrupted by the first optical isolator 12A, becoming discarded light. On the other hand, in the composite light involved in the second light incident on the second imaging system 4B, the reference light component and the measurement light component are respectively converted into circularly polarized light and captured as interference light.

[0191] As detailed above, this embodiment achieves the same effects as the first embodiment described above. Furthermore, this embodiment allows for the integration and configuration of various devices.

[0192] However, in this embodiment, in addition to the semi-transparent mirror HM, the amount of light incident on the imaging systems 4A and 4B is further halved by the beam splitters 13A and 13B. Therefore, the first embodiment is preferred in this respect.

[0193] [Third Implementation Method]

[0194] The following is for reference. Figure 7 The third embodiment will be described. The main difference between this embodiment and the first embodiment lies in the configuration of the projection systems 2A and 2B and the imaging systems 4A and 4B. Therefore, in this embodiment, the features that differ from the first embodiment will be described in detail, while the same structural parts will be labeled with the same reference numerals, and detailed descriptions of these parts will be omitted.

[0195] In this embodiment, the first light emitted from the first projection system 2A (first light-emitting part 11A) and the second light emitted from the second projection system 2B (second light-emitting part 11B) are both incident on the first surface HMa of the semi-transparent and semi-reflective mirror HM.

[0196] In detail, the optical axis (emission direction of the first light) JA1 of the first light-emitting unit 11A is tilted to the right by an angle θ1 relative to the Z-axis direction, and the optical axis JB1 (emission direction of the second light) of the second light-emitting unit 11B is tilted to the left by an angle θ2 relative to the Z-axis direction. However, in this embodiment, angles θ1 and θ2 are set to the same angle, resulting in a structure in which the first light-emitting system 2A and the second light-emitting system 2B are symmetrically arranged with the Z-axis direction as the center.

[0197] Furthermore, in this embodiment, the first imaging system 4A is configured to be incident with composite light involving the first light emitted from the second surface HMb of the semi-transparent mirror HM, and the second imaging system 4B is configured to be incident with composite light involving the second light emitted from the second surface HMb of the semi-transparent mirror HM.

[0198] Specifically, the optical axis JA2 of the first camera 33A (the incident direction of the composite light involved in the first light) is tilted upward by an angle θ1 relative to the X-axis direction, and the optical axis JB2 of the second camera 33B (the incident direction of the composite light involved in the second light) is tilted downward by an angle θ2 relative to the X-axis direction. Therefore, in this embodiment, the first imaging system 4A and the second imaging system 4B are arranged symmetrically about the X-axis direction.

[0199] Next, the optical path of the first light according to this embodiment will be described. The first light emitted from the first projection system 2A is incident on the first position P1 of the semi-transparent mirror HM. Then, the first light follows the same optical path as in the first embodiment described above, and the composite light, which combines the reference light (P-polarized light) and the measurement light (S-polarized light) of the first light, is emitted from the second position P2 of the semi-transparent mirror HM toward the second projection system 2B and the first imaging system 4A.

[0200] In this system, the composite light (reference light and measurement light) involved in the first light incident on the second projection system 2B is interrupted by the second optical isolator 12B, becoming discarded light. On the other hand, in the composite light involved in the first light incident on the first imaging system 4A, the reference light component and the measurement light component are respectively converted into circularly polarized light and captured as interference light.

[0201] Next, the optical path of the second light according to this embodiment will be described. The second light with wavelength λ2 (linearly polarized light whose polarization direction is tilted at 45° with respect to the X-axis and Y-axis directions) is emitted from the second light projection system 2B (second light emission part 11B) toward the interference optical system 3.

[0202] The second light emitted from the second projection system 2B is incident on the second position P2 of the semi-transparent mirror HM. Therefore, the "second position P2 of the semi-transparent mirror HM" constitutes the "second input section" in this embodiment.

[0203] For the second light incident on the second position P2 of the semi-transparent mirror HM, a portion (half) is reflected by the first surface HMa and emitted toward the polarizer 21, while the remaining portion (half) passes through the semi-transparent mirror HM and is emitted from the second surface HMb toward the polarizer 22.

[0204] The second light reflected by the first surface HMa of the semi-transparent mirror HM is incident on the polarizer 21, with only its P-polarized component passing through the polarizer 21. The P-polarized component of the second light that has passed through the polarizer 21 serves as a reference light and is reflected off the reference surface 23. Here, the angle of incidence and the angle of reflection of the reference light (P-polarized light) related to the second light relative to the reference surface 23 are the aforementioned angles θ2 (=θ1).

[0205] Subsequently, the reference light (P-polarized light) involved in the second light reflected by the reference surface 23 passes through the polarizer 21 again and is incident on the first position P1 of the semi-transparent mirror HM. For the reference light involved in the second light incident on the first position P1 of the semi-transparent mirror HM, a portion (half) is reflected by the first surface HMa and emitted towards the first projection system 2A, while the remaining portion (half) passes through the semi-transparent mirror HM and is emitted from the second surface HMb towards the second imaging system 4B.

[0206] On the other hand, the second light incident from the second projection system 2B onto the second position P2 of the semi-transparent mirror HM, and passing through the semi-transparent mirror HM, is incident on the polarizer 22, with only its S-polarized component passing through the polarizer 22. The S-polarized component of the second light passing through the polarizer 22 is used as measurement light to illuminate the workpiece W and is reflected. Here, the angle of incidence and the angle of reflection of the measurement light related to the second light relative to the setting unit 24 (workpiece W) are the aforementioned angles θ2 (=θ1).

[0207] Subsequently, the measurement light (S-polarized light) involved in the second light reflected by the workpiece W passes through the polarizer 22 again and is incident on the first position P1 of the semi-transparent mirror HM. For the measurement light involved in the second light incident on the first position P1 of the semi-transparent mirror HM, a portion (half) passes through the semi-transparent mirror HM and is emitted from the first surface HMa toward the first projection system 2A, while the remaining portion (half) is reflected by the second surface HMb and is emitted toward the second imaging system 4B.

[0208] That is, at the first position P1 of the semi-transparent mirror HM, the measurement light (S-polarized light) involving the second light reflected by the second surface HMb and the reference light (P-polarized light) involving the second light transmitted to the second surface HMb are combined, and the measurement light (S-polarized light) involving the second light transmitted to the first surface HMa and the reference light (P-polarized light) involving the second light reflected by the first surface HMa are combined.

[0209] As a result, the composite light, which combines the reference light (P-polarized light) and the measurement light (S-polarized light) involved in the second light synthesis, is emitted as the output light from the first position P1 of the semi-transparent mirror HM to the second imaging system 4B and the first projection system 2A, respectively. Therefore, the "first position P1 of the semi-transparent mirror HM" constitutes the "second output unit" in this embodiment.

[0210] Among them, the composite light (reference light and measurement light) involved in the second light incident on the first projection system 2A is interrupted by the first optical isolator 12A and becomes discarded light.

[0211] On the other hand, in the composite light involved in the second light incident on the second imaging system 4B, the reference light component and the measurement light component are respectively converted into circularly polarized light and photographed as interference light.

[0212] As detailed above, this embodiment achieves the same effects as the first embodiment described above.

[0213] [Fourth Implementation Method]

[0214] The following is for reference. Figure 8The fourth embodiment will be described. This embodiment has the same features as the second embodiment, but differs from the third embodiment mainly in the configuration structure of the imaging systems 4A and 4B. Therefore, in this embodiment, the features that differ from the second and third embodiments will be described in detail, the same structural parts will be labeled with the same reference numerals, and detailed descriptions of them will be omitted.

[0215] The first imaging system 4A according to this embodiment is configured to capture the light emitted towards the second projection system 2B from the composite light of the first light emitted in both directions from the second position P2 of the semi-transparent mirror HM. Similarly, the second imaging system 4B according to this embodiment is configured to capture the light emitted towards the first projection system 2A from the composite light of the second light emitted in both directions from the first position P1 of the semi-transparent mirror HM. Detailed descriptions will follow.

[0216] In this embodiment, a first beam splitter 13A is provided between the second projection system 2B and the semi-transparent mirror HM, arranged in a manner that overlaps with the optical axis JB1 of the second light-emitting part 11B.

[0217] The first beam splitter 13A is configured such that one of its two adjacent surfaces, which is perpendicular to the optical axis JB1 of the second light-emitting part 11B, is perpendicular to the optical axis JA2 of the first camera 33A. That is, the bonding surface 13Ah of the first beam splitter 13A is configured to be tilted at 45° relative to the optical axes JB1 and JA2.

[0218] Thus, a portion (half) of the composite light involved in the first light emitted from the first surface HMa of the second position P2 of the semi-transparent mirror HM can be transmitted to the second projection system 2B side via the first beam splitter 13A, while the remaining portion (half) is reflected to the first imaging system 4A side and incident.

[0219] Furthermore, in this embodiment, a second beam splitter 13B is provided between the first light projection system 2A and the semi-transparent mirror HM, arranged in a manner that overlaps with the optical axis JA1 of the first light-emitting part 11A.

[0220] The second beam splitter 13B is configured such that one of its two adjacent surfaces, sandwiching its mating surface 13Bh, is orthogonal to the optical axis JA1 of the first light-emitting part 11A and the other is orthogonal to the optical axis JB2 of the second camera 33B. That is, the mating surface 13Bh of the second beam splitter 13B is configured to be tilted at 45° relative to the optical axes JA1 and JB2.

[0221] Thus, via the second beam splitter 13B, a portion (half) of the composite light involved in the second light emitted from the first surface HMa of the first position P1 of the semi-transparent mirror HM can be transmitted to the first projection system 2A side, while the remaining portion (half) is reflected to the second imaging system 4B side and incident.

[0222] Next, the optical path of the first light according to this embodiment will be described. The first light emitted from the first projection system 2A is incident on the second beam splitter 13B.

[0223] A portion (half) of the first light incident on the second beam splitter 13B passes through the bonding surface 13Bh and is incident on the first position P1 of the semi-transparent mirror HM. On the other hand, the remaining portion (half) of the first light incident on the second beam splitter 13B is reflected by the bonding surface 13Bh and becomes discarded light.

[0224] Then, the first light incident on the first position P1 of the semi-transparent mirror HM follows the same optical path as in the first embodiment described above, and the composite light, which combines the reference light (P-polarized light) and the measurement light (S-polarized light) involved in the first light, is emitted from the second position P2 of the semi-transparent mirror HM to the first beam splitter 13A.

[0225] A portion (half) of the composite light (reference light and measurement light) involved in the first beam splitter 13A is incident on the second projection system 2B through the bonding surface 13Ah, while the remaining portion (half) is reflected by the bonding surface 13Ah and incident on the first imaging system 4A.

[0226] In this system, the composite light (reference light and measurement light) involved in the first light incident on the second projection system 2B is interrupted by the second optical isolator 12B, becoming discarded light. On the other hand, in the composite light involved in the first light incident on the first imaging system 4A, the reference light component and the measurement light component are respectively converted into circularly polarized light and captured as interference light.

[0227] Next, the optical path of the second light according to this embodiment will be described. The second light emitted from the second projection system 2B is incident on the first beam splitter 13A.

[0228] A portion (half) of the second light incident on the first beam splitter 13A passes through the bonding surface 13Ah and is incident on the second position P2 of the semi-transparent mirror HM. On the other hand, the remaining portion (half) of the second light incident on the first beam splitter 13A is reflected by the bonding surface 13Ah and becomes discarded light.

[0229] Then, the second light incident on the second position P2 of the semi-transparent mirror HM follows the same optical path as in the third embodiment described above. The combined light, which is a reference light (P-polarized light) and a measurement light (S-polarized light) of the second light, is emitted from the first position P1 of the semi-transparent mirror HM to the second beam splitter 13B.

[0230] A portion (half) of the composite light (reference light and measurement light) involved in the second beam splitter 13B is incident on the first projection system 2A through the bonding surface 13Bh, while the remaining portion (half) is reflected by the bonding surface 13Bh and incident on the second imaging system 4B.

[0231] In this system, the composite light (reference light and measurement light) involved in the second light incident on the first projection system 2A is interrupted by the first optical isolator 12A, becoming discarded light. On the other hand, in the composite light involved in the second light incident on the second imaging system 4B, the reference light component and the measurement light component are respectively converted into circularly polarized light and captured as interference light.

[0232] As detailed above, this embodiment achieves the same effects as the first embodiment described above. Furthermore, this embodiment allows for the integration and configuration of various devices.

[0233] However, similar to the second embodiment, in this embodiment, in addition to the semi-transparent and semi-reflective mirror HM, the amount of light incident on the imaging systems 4A and 4B is further halved by the beam splitters 13A and 13B. Therefore, the third embodiment is preferred in this respect.

[0234] [Fifth Implementation]

[0235] The following is for reference. Figure 9 The fifth embodiment will now be described. This embodiment differs from the first embodiment in that it includes various lenses. Therefore, in this embodiment, the features that differ from the first embodiment will be described in detail, the same structural parts will be labeled with the same reference numerals, and detailed descriptions of those parts will be omitted.

[0236] In the interference optical system 3 of this embodiment, an objective lens L1 is arranged between the semi-transparent mirror HM and the polarizing plate 21, facing the polarizing plate 21 in the X-axis direction, and an objective lens L2 is arranged between the semi-transparent mirror HM and the polarizing plate 22, facing the polarizing plate 22 in the Z-axis direction.

[0237] Objective lens L1 is configured such that the focal position on one side is aligned with reference plane 23 and the focal position on the other side (first imaging system 4A side and second imaging system 4B side) overlaps with the focal position on the other side (interference optical system 3 side) of imaging lens L4A (described later) and the focal position on the other side (interference optical system 3 side) of imaging lens L4B (described later).

[0238] The objective lens L2 is configured such that the focal position on one side is aligned with the setting part 24, and the focal position on the other side (the side of the first imaging system 4A and the side of the second imaging system 4B) overlaps with the focal position on the other side (the side of the interference optical system 3) of the imaging lens L4A (described later) and the focal position on the other side (the side of the interference optical system 3) of the imaging lens L4B (described later).

[0239] Furthermore, objective lenses L1 and L2 can also be composed of lens units, which are composed of multiple lenses. Of course, they can also be composed of a single lens. In addition, the above configuration structure can be substituted, for example, by arranging objective lens L1 between polarizing plate 21 and reference plane 23. Similarly, objective lens L2 can be arranged between polarizing plate 22 and setting part 24 (workpiece W).

[0240] Furthermore, in this embodiment, the first light projection system 2A includes a light projection lens L3A positioned between the first optical isolator 12A and the semi-transparent mirror HM, arranged in a manner that overlaps with the optical axis JA1 of the first light-emitting unit 11A. The light projection lens L3A has the function of focusing the first light emitted from the first light-emitting unit 11A toward the objective lenses L1 and L2.

[0241] Similarly, in this embodiment, the second projection system 2B includes a projection lens L3B positioned between the second optical isolator 12B and the semi-transparent mirror HM, which overlaps with the optical axis JB1 of the second light-emitting unit 11B. The projection lens L3B has the function of focusing the second light emitted from the second light-emitting unit 11B toward the objective lenses L1 and L2.

[0242] Furthermore, the configuration of the projection lenses L3A and L3B is not limited to the above-described configuration. For example, the projection lens L3A may be configured to be positioned between the first light-emitting part 11A and the first optical isolator 12A. Similarly, the projection lens L3B may be configured to be positioned between the second light-emitting part 11B and the second optical isolator 12B.

[0243] Furthermore, in this embodiment, the first imaging system 4A has an imaging lens L4A arranged between the quarter-wave plate 31A and the semi-transparent mirror HM, which overlaps with the optical axis JA2 of the first camera 33A.

[0244] The imaging lens L4A is aligned with the polarization image sensor 70A on one side (the first camera 33A side), and the focal position on the other side (the interference optical system 3 side) overlaps with the focal positions of the first imaging system 4A side of the reference light objective lens L1 and the first imaging system 4A side of the measurement light objective lens L2, respectively.

[0245] That is, the imaging lens L4A has the function of imaging the composite light involved in the first light emitted from the semi-transparent mirror HM onto the first camera 33A (polarization image sensor 70A).

[0246] Similarly, in this embodiment, the second imaging system 4B has an imaging lens L4B arranged between the quarter-wave plate 31B and the semi-transparent mirror HM, which overlaps with the optical axis JB2 of the second camera 33B.

[0247] The imaging lens L4B is aligned with the polarization image sensor 70B on one side (the second camera 33B side), and the focal position on the other side (the interference optical system 3 side) overlaps with the focal positions of the second imaging system 4B side of the reference light objective lens L1 and the second imaging system 4B side of the measurement light objective lens L2, respectively.

[0248] That is, the imaging lens L4B has the function of imaging the composite light involved in the second light emitted from the semi-transparent mirror HM onto the second camera 33B (polarization image sensor 70B).

[0249] Furthermore, the imaging lenses L4A and L4B can also be composed of lens units, which are composed of multiple lenses. Alternatively, they can be composed of a single lens. Furthermore, instead of the above configuration, the imaging lens L4A can be configured, for example, between the quarter-wave plate 31A and the first camera 33A. Similarly, the imaging lens L4B can be configured between the quarter-wave plate 31B and the second camera 33B.

[0250] In addition, such as Figure 10 As shown in (a) and (b), the incident angle θ1 of the first light relative to the reference plane 23 and the setting part 24 when the objective lenses L1 and L2 are configured needs to satisfy the following equation (2). Of course, the same applies to the incident angle θ2 of the second light.

[0251] 0<θ1<θ NA …(2)

[0252] Here, “θ NA "This indicates the maximum incident angle of the first light that can be incident on the reference surface 23 and the setting part 24 through the objective lenses L1 and L2 with numerical aperture NA (the maximum angle relative to the central axis JO of objective lenses L1 and L2).

[0253] Furthermore, the numerical aperture NA of objectives L1 and L2 can be expressed by the following formula (3).

[0254] NA = n × sinθ NA …(3)

[0255] Here, "n" represents the refractive index of the medium between the reference plane 23 and the objective lens L1. If the medium is air, then n≈1.

[0256] In addition, such as comparison Figure 10 As shown in (a) and (b), as long as the incident angle θ1 of the first light is as small as possible, a larger area can be illuminated with uniform parallel light. This results in more uniform measurement of a larger area and further improvement in measurement accuracy. The same applies to the incident angle θ2 of the second light.

[0257] As detailed above, this embodiment achieves the same effects as the first embodiment described above.

[0258] Furthermore, this embodiment includes objective lenses L1 and L2, projection lenses L3A and L3B, and imaging lenses L4A and L4B. This allows for the acquisition of image data with the focal point on the workpiece W, and also enables magnified imaging of the workpiece W. As a result, improved measurement accuracy is achieved.

[0259] Furthermore, as in this embodiment, in a structure equipped with objective lenses L1 and L2, the light (measuring light) irradiating the workpiece W is concentrated at a single point (a narrow range), thus potentially narrowing the measurable area.

[0260] In contrast, this embodiment includes projection lenses L3A and L3B. By focusing the light emitted from the light-emitting units 11A and 11B onto the objective lenses L1 and L2, uniform parallel light can be irradiated over a larger area of ​​the workpiece W. As a result, a larger area can be measured more uniformly, further improving measurement accuracy and efficiency.

[0261] [Sixth Implementation Method]

[0262] The following is for reference. Figure 11 The sixth embodiment will be described. This embodiment differs from the first embodiment mainly in the structure of the interference optical system 3. Therefore, in this embodiment, the features that differ from the first embodiment will be described in detail, the same structural parts will be labeled with the same reference numerals, and detailed descriptions of those parts will be omitted.

[0263] The interference optical system 3 involved in this embodiment has a beam splitter (BS) 20 to replace the semi-transparent mirror HM.

[0264] The beam splitter 20 is a known cubic optical component that integrates right-angle prisms into a single unit, and a coating such as a metal film is applied to its bonding surface (boundary surface) 20h.

[0265] Like the semi-transparent mirror HM, the beam splitter 20 also includes polarization states, splitting the incident light into transmitted light and reflected light at a predetermined ratio (1:1 in this embodiment). Thus, the P-polarized and S-polarized components of the transmitted light, as well as the P-polarized and S-polarized components of the reflected light, are all split at the same ratio, and the polarization states of the transmitted and reflected light are the same as those of the incident light.

[0266] The beam splitter 20 is configured such that one of its two adjacent surfaces, which sandwich its mating surface 20h, is orthogonal to the X-axis direction and the other is orthogonal to the Z-axis direction. That is, the mating surface 20h of the beam splitter 20 is configured to be inclined at 45° relative to the X-axis direction and the Z-axis direction.

[0267] More specifically, the first surface (upper side in the Z-axis direction) 20a of the beam splitter 20 into which the first light emitted from the first light-emitting system 2A (first light-emitting part 11A) is incident and the third surface (lower side in the Z-axis direction) 20c opposite to the first surface 20a are arranged in a manner orthogonal to the Z-axis direction.

[0268] On the other hand, the second surface (left side in the X-axis direction) 20b of the beam splitter 20, which is adjacent to the first surface 20a across the joint surface 20h and is the incident surface of the second light emitted from the second light projection system 2B (second light-emitting part 11B), and the fourth surface (right side in the X-axis direction) 20d opposite to the second surface 20b are arranged in a manner orthogonal to the X-axis direction.

[0269] Furthermore, in the interference optical system 3 according to this embodiment, the polarizer 21 is arranged opposite to the fourth surface 20d of the beam splitter 20 in the X-axis direction, and the reference surface 23 is arranged opposite to the polarizer 21 in the X-axis direction.

[0270] That is, only the P-polarized component of the light emitted from the fourth surface 20d of the beam splitter 20 passes through the polarizer 21 and is used as reference light to illuminate the reference surface 23. Furthermore, the reference light (P-polarized light) reflected by the reference surface 23 passes through the polarizer 21 again and is incident on the fourth surface 20d of the beam splitter 20.

[0271] On the other hand, the polarizer 22 is arranged opposite to the third surface 20c of the beam splitter 20 in the Z-axis direction, and the setting part 24 is arranged opposite to the polarizer 22 in the Z-axis direction.

[0272] That is, only the S-polarized component of the light emitted from the third surface 20c of the beam splitter 20 passes through the polarizer 22 and is used as measurement light to illuminate the workpiece W placed in the setting section 24, the workpiece W being the object to be measured. Furthermore, the measurement light (S-polarized light) reflected by the workpiece W passes through the polarizer 22 again and is incident on the third surface 20c of the beam splitter 20.

[0273] Next, the optical path of the first beam will be explained. The first beam is emitted from the first projection system 2A toward the interference optical system 3.

[0274] The first light emitted from the first projection system 2A is incident on the first position 20a1 of the first surface 20a of the beam splitter 20. Therefore, the "first position 20a1 of the first surface 20a of the beam splitter 20" constitutes the "first input section" in this embodiment.

[0275] In this embodiment, the optical axis (light emission direction) JA1 of the first light-emitting part 11A is tilted to the right by an angle θ1 relative to the Z-axis direction. This angle θ1 becomes the incident angle of the first light towards the first surface 20a.

[0276] The first light incident from the first surface 20a of the beam splitter 20 is refracted at a predetermined angle of refraction. At the first position 20h1 of the bonding surface 20h, a portion (half) of the light is reflected by the bonding surface 20h and refracted at the first position 20d1 of the fourth surface 20d at a predetermined angle of refraction, and then emitted toward the polarizer 21. On the other hand, the remaining portion (half) passes through the bonding surface 20h and is refracted at the first position 20c1 of the third surface 20c at a predetermined angle of refraction, and then emitted toward the polarizer 22.

[0277] The first light emitted from the first position 20d1 of the fourth surface 20d of the beam splitter 20 is incident on the polarizer 21, and only its P-polarized component passes through the polarizer 21. The P-polarized component of the first light that has passed through the polarizer 21 serves as a reference light and illuminates and is reflected from the reference surface 23. Here, the angle of incidence and the angle of reflection of the reference light (P-polarized light) of the first light relative to the reference surface 23 are the aforementioned angles θ1.

[0278] Subsequently, the reference light (P-polarized light) involved in the first light reflected by the reference surface 23 passes through the polarizer 21 again and is incident on the second position 20d2 of the fourth surface 20d of the beam splitter 20.

[0279] The reference light involved in the first light incident from the second position 20d2 of the fourth surface 20d of the beam splitter 20 is refracted at a predetermined angle of refraction. At the second position 20h2 of the bonding surface 20h, a portion (half) of it is reflected by the bonding surface 20h and refracted at the second position 20a2 of the first surface 20a of the beam splitter 20 at a predetermined angle of refraction, and emitted toward the first imaging system 4A. On the other hand, the remaining portion (half) passes through the bonding surface 20h and is refracted at the first position 20b1 of the second surface 20b of the beam splitter 20 at a predetermined angle of refraction, and emitted toward the second projection system 2B.

[0280] On the other hand, the first light emitted from the first position 20c1 of the third surface 20c of the beam splitter 20 is incident on the polarizer 22, and only its S-polarized light component passes through the polarizer 22. The S-polarized light component of the first light that passes through the polarizer 22 is used as measurement light to illuminate the workpiece W and is reflected. Here, the angle of incidence and the angle of reflection of the measurement light involved in the first light relative to the setting part 24 (workpiece W) are the aforementioned angle θ1.

[0281] Subsequently, the measurement light (S-polarized light) involved in the first light reflected by the workpiece W passes through the polarizer 22 again and is incident on the second position 20c2 of the third surface 20c of the beam splitter 20.

[0282] The first light incident from the second position 20c2 of the third surface 20c of the beam splitter 20 involves measurement light that is refracted at a predetermined angle. At the second position 20h2 of the junction surface 20h, a portion (half) of the light is reflected by the junction surface 20h and refracted at the first position 20b1 of the second surface 20b of the beam splitter 20 at a predetermined angle, and emitted toward the second projection system 2B. On the other hand, the remaining portion (half) passes through the junction surface 20h, is refracted at the second position 20a2 of the first surface 20a of the beam splitter 20 at a predetermined angle, and emitted toward the first imaging system 4A.

[0283] That is, at the second position 20h2 of the bonding surface 20h, a reference light (P-polarized light) involving the first light reflected by the bonding surface 20h and a measurement light (S-polarized light) involving the first light transmitted through the bonding surface 20h are synthesized, and a reference light (P-polarized light) involving the first light transmitted through the bonding surface 20h and a measurement light (S-polarized light) involving the first light reflected by the bonding surface 20h are synthesized.

[0284] As a result, the composite light, which combines the reference light (P-polarized light) and the measurement light (S-polarized light) involved in the first light, is emitted as the output light from the second position 20a2 of the first surface 20a of the beam splitter 20 toward the first imaging system 4A, and from the first position 20b1 of the second surface 20b of the beam splitter 20 toward the second projection system 2B. Therefore, the "second position 20a2 of the first surface 20a of the beam splitter 20" constitutes the "first output section" in this embodiment.

[0285] In this system, the composite light (reference light and measurement light) involved in the first light incident on the second projection system 2B is interrupted by the second optical isolator 12B, becoming discarded light. On the other hand, in the composite light involved in the first light incident on the first imaging system 4A, the reference light component and the measurement light component are respectively converted into circularly polarized light and captured as interference light.

[0286] Next, the optical path of the second light will be explained. The second light is emitted from the second projection system 2B into the interference optical system 3.

[0287] The second light emitted from the second projection system 2B is incident on the first position 20b1 of the second surface 20b of the beam splitter 20. Therefore, the "first position 20b1 of the second surface 20b of the beam splitter 20" constitutes the "second input section" in this embodiment.

[0288] In this embodiment, the optical axis (light emission direction) JB1 of the second light-emitting part 11B is tilted upward by an angle θ2 relative to the X-axis direction. This angle θ2 becomes the incident angle of the second light towards the second surface 20b.

[0289] The second light incident from the second surface 20b of the beam splitter 20 is refracted at a predetermined angle of refraction. At the second position 20h2 of the bonding surface 20h, a portion (half) of the light is reflected by the bonding surface 20h and refracted at the second position 20c2 of the third surface 20c at a predetermined angle of refraction, and then emitted toward the polarizer 22. On the other hand, the remaining portion (half) passes through the bonding surface 20h and is refracted at the second position 20d2 of the fourth surface 20d at a predetermined angle of refraction, and then emitted toward the polarizer 21.

[0290] The second light emitted from the second position 20d2 of the fourth surface 20d of the beam splitter 20 is incident on the polarizer 21, with only its P-polarized component passing through the polarizer 21. The P-polarized component of the second light that has passed through the polarizer 21 serves as a reference light and illuminates and is reflected from the reference surface 23. Here, the angle of incidence and the angle of reflection of the reference light (P-polarized light) related to the second light relative to the reference surface 23 are the aforementioned angles θ2 (=θ1).

[0291] Subsequently, the reference light (P-polarized light) involved in the second light reflected by the reference surface 23 passes through the polarizer 21 again and is incident on the first position 20d1 of the fourth surface 20d of the beam splitter 20.

[0292] The reference light incident from the first position 20d1 of the fourth surface 20d of the beam splitter 20 is refracted at a predetermined angle. At the first position 20h1 of the bonding surface 20h, a portion (half) of the light is reflected by the bonding surface 20h and refracted at the first position 20a1 of the first surface 20a of the beam splitter 20 at a predetermined angle, and emitted toward the first projection system 2A. On the other hand, the remaining portion (half) passes through the bonding surface 20h and is refracted at the second position 20b2 of the second surface 20b of the beam splitter 20 at a predetermined angle, and emitted toward the second imaging system 4B.

[0293] On the other hand, the second light emitted from the second position 20c2 of the third surface 20c of the beam splitter 20 is incident on the polarizer 22, and only its S-polarized light component passes through the polarizer 22. The S-polarized light component of the second light that passes through the polarizer 22 is used as measurement light to illuminate the workpiece W and is reflected. Here, the incident angle and reflection angle of the measurement light related to the second light relative to the setting part 24 (workpiece W) are the aforementioned angles θ2 (=θ1).

[0294] Subsequently, the measurement light (S-polarized light) involved by the second light reflected by the workpiece W passes through the polarizer 22 again and is incident on the first position 20c1 of the third surface 20c of the beam splitter 20.

[0295] The second light incident from the first position 20c1 of the third surface 20c of the beam splitter 20 is the measuring light involved. It is refracted at a specified angle. At the first position 20h1 of the bonding surface 20h, a portion (half) of it is reflected by the bonding surface 20h and refracted at the second position 20b2 of the second surface 20b of the beam splitter 20 at a specified angle, and emitted toward the second imaging system 4B. On the other hand, the remaining portion (half) is refracted through the bonding surface 20h from the first position 20a1 of the first surface 20a of the beam splitter 20 at a specified angle and emitted toward the first projection system 2A.

[0296] That is, at the first position 20h1 of the bonding surface 20h, a reference light (P-polarized light) involving the second light reflected by the bonding surface 20h and a measurement light (S-polarized light) involving the second light transmitted through the bonding surface 20h are synthesized, and a reference light (P-polarized light) involving the second light transmitted through the bonding surface 20h and a measurement light (S-polarized light) involving the second light reflected by the bonding surface 20h are synthesized.

[0297] As a result, the composite light, which combines the reference light (P-polarized light) and the measurement light (S-polarized light) involved in the second light synthesis, is emitted as the output light from the first position 20a1 of the first surface 20a of the beam splitter 20 toward the first projection system 2A, and from the second position 20b2 of the second surface 20b of the beam splitter 20 toward the second imaging system 4B. Therefore, the "second position 20b2 of the second surface 20b of the beam splitter 20" constitutes the "second output section" in this embodiment.

[0298] In this system, the composite light (reference light and measurement light) involved in the second light incident on the first projection system 2A is interrupted by the first optical isolator 12A, becoming discarded light. On the other hand, in the composite light involved in the second light incident on the second imaging system 4B, the reference light component and the measurement light component are respectively converted into circularly polarized light and captured as interference light.

[0299] As detailed above, this embodiment achieves the same effects as the first embodiment described above.

[0300] In addition to the structure of this embodiment, it can also be configured as described in the fifth embodiment above, including objective lenses L1 and L2, projection lenses L3A and L3B, and imaging lenses L4A and L4B.

[0301] However, when the beam splitter 20, which refracts light significantly, is equipped with objective lenses L1, L2, etc., the light converged by objective lenses L1, L2, etc. may not be concentrated at a single point. Therefore, when the objective lenses L1, L2, etc. are configured, as an optical unit, it is preferable to use a thin plate-shaped semi-transparent and semi-reflective mirror HM, which can substantially disregard refraction compared to the beam splitter 20.

[0302] [Seventh Implementation Method]

[0303] The following is for reference. Figure 12 The seventh embodiment will be described. This embodiment differs from the first embodiment mainly in the structure and operation method of the interference optical system 3. Therefore, in this embodiment, the features that differ from the first embodiment will be described in detail, the same reference numerals will be used for the same structural parts, and detailed descriptions of those parts will be omitted. Furthermore, in the previous embodiments, the angles formed by the reference plane 23 and the semi-transparent mirror HM, and the angles formed by the reference plane 23 and the junction surface 20h of the beam splitter 20, were 45°, but in this embodiment, they are slightly tilted from 45°. Therefore, the optical path and... Figure 12 While not strictly consistent, the slight inclination angles are so small that any deviations in the positional relationships of the symbols are to the extent that they will not affect the following explanation.

[0304] The interference optical system 3 involved in this embodiment differs from that in the first embodiment, and does not have polarizing plates 21, 22 and quarter-wavelength plates 31A, 31B.

[0305] Cameras 33A and 33B use general CCD and CMOS elements as image sensors, while cameras 70A and 70B are not polarization image sensors.

[0306] The brightness image data captured and acquired by the first camera 33A is converted into a digital signal inside the first camera 33A and then input to the control device 5 (image data storage device 54) in the form of a digital signal.

[0307] Similarly, the brightness image data captured and acquired by the second camera 33B is converted into a digital signal inside the second camera 33B and then input to the control device 5 (image data storage device 54) in the form of a digital signal.

[0308] Next, the optical path of the first ray will be explained. For example... Figure 12 As shown, a first light with wavelength λ1 is emitted from the first light projection system 2A (first light-emitting part 11A) toward the interference optical system 3. Here, the direction of light travel (vector) is tilted at an angle θ1 relative to the Z-axis direction.

[0309] The first light emitted from the first projection system 2A is incident on the first position P1 of the semi-transparent mirror HM. Therefore, the "first position P1 of the semi-transparent mirror HM" constitutes the "first input unit" in this embodiment.

[0310] The first light source only needs to be a light source with a coherence length that can interfere with the image sensor with sufficient contrast even when the reference mirror is tilted at an angle that enables the Fourier transform method described later.

[0311] For the first light incident on the first position P1 of the semi-transparent mirror HM, a portion (half) is reflected by the first surface HMa and emitted toward the reference surface 23, while the remaining portion (half) passes through the semi-transparent mirror HM and is emitted from the second surface HMb toward the setting part 24.

[0312] The first light reflected by the first surface HMa of the semi-transparent mirror HM is used as a reference light to illuminate the reference surface 23 and then reflected. Here, the angle of incidence and the angle of reflection of the reference light with respect to the reference surface 23 are referred to as the aforementioned angle θ1.

[0313] Subsequently, the reference light involved in the first light reflected by the reference surface 23 is incident again on the second position P2 of the semi-transparent mirror HM. For the reference light involved in the first light incident on the second position P2 of the semi-transparent mirror HM, a portion (half) is reflected by the first surface HMa and emitted toward the first imaging system 4A, while the remaining portion (half) passes through the semi-transparent mirror HM and is emitted from the second surface HMb toward the second projection system 2B.

[0314] On the other hand, the first light incident from the first projection system 2A onto the first position P1 of the semi-transparent mirror HM, and passing through the semi-transparent mirror HM, is used as the measurement light to illuminate the workpiece W and is reflected. Here, the angle of incidence and the angle of reflection of the measurement light related to the first light relative to the setting unit 24 (workpiece W) are the aforementioned angle θ1.

[0315] Subsequently, the measurement light involved in the first light reflected by the workpiece W is again incident on the second position P2 of the semi-transparent mirror HM. For the measurement light involved in the first light incident on the second position P2 of the semi-transparent mirror HM, a portion (half) passes through the semi-transparent mirror HM and is emitted from the first surface HMa toward the first imaging system 4A, while the remaining portion (half) is reflected by the second surface HMb and is emitted toward the second projection system 2B.

[0316] That is, at the second position P2 of the semi-transparent mirror HM, a reference light involving the first light reflected by the first surface HMa and a measurement light involving the first light transmitted to the first surface HMa are synthesized, and a reference light involving the first light transmitted to the second surface HMb and a measurement light involving the first light reflected by the second surface HMb are synthesized.

[0317] As a result, the composite light, which combines the reference light and the measurement light involved in the first light, is emitted as the output light from the interferometric optical system 3 from the second position P2 of the semi-transparent mirror HM to the first imaging system 4A and the second projection system 2B, respectively. Therefore, the "second position P2 of the semi-transparent mirror HM" constitutes the "first output unit" in this embodiment.

[0318] Among them, the composite light (reference light and measurement light) involved in the first light incident on the second projection system 2B is interrupted by the second optical isolator 12B and becomes discarded light.

[0319] On the other hand, the composite light (reference light and measurement light) involved in the first light incident on the first imaging system 4A interferes with the image sensor 70A, so the first camera 33A obtains an interference fringe image generated by the first light source.

[0320] As described above, in the previous embodiment, the reference plane 23 formed an angle of 45° with the semi-transparent mirror HM. However, in this embodiment, carrier fringes are generated in the interference fringe image by slightly tilting it from 45°. The direction in which the reference plane (reference mirror) 23 is tilted can be a direction with an angle greater than 45° with the semi-transparent mirror HM, or a direction with an angle less than 45°. Furthermore, based on the properties of the Fourier transform method, if the pixel pitch of the image sensor is set to D, the wavelength used is set to λ, and the tilt angle of the reference plane 23 from 45° is set to θ3, then |θ3| ≤ tan tan θ3. -1(λ / 2D). Furthermore, by tilting the reference plane 23, the optical axes JA2 and JB2 no longer pass through the centers of cameras 33A and 33B, but because the light rays have sufficient width, the reference light is incident on cameras 33A and 33B. In the absence of incident light, adjustments are made by adjusting the tilt angle to the degree of incident light, or by making the light rays thicker, etc. Furthermore, the measurement method based on the Fourier transform method, which generates an interference fringe image of carrier fringes by intentionally tilting the reference plane 23 as described above, to obtain the complex amplitude of the measurement light, is a well-known technique (see, for example, Japanese Patent No. 6271493, paragraphs 372-377), and therefore its detailed description is omitted.

[0321] Next, the optical path of the second ray will be explained. For example... Figure 12 As shown, a second light with wavelength λ2 is emitted from the second light-emitting system 2B (second light-emitting part 11B) toward the interference optical system 3. Here, the direction of light travel (vector) is tilted at an angle θ2 (=θ1) relative to the X-axis direction.

[0322] The second light, like the first light, only needs to be a light source with a coherence length that allows interference with sufficient contrast on the image sensor even when the reference plane (reference mirror) 23 is tilted at an angle that enables the Fourier transform method to be performed.

[0323] The second light emitted from the second projection system 2B is incident on the second position P2 of the semi-transparent mirror HM. Therefore, the "second position P2 of the semi-transparent mirror HM" constitutes the "second input section" in this embodiment.

[0324] For the second light incident on the second position P2 of the semi-transparent and semi-reflective mirror HM, a portion (half) of it passes through the semi-transparent and semi-reflective mirror HM and is emitted toward the reference surface 23, while the remaining portion (half) is reflected by the second surface HMb and is emitted toward the setting part 24.

[0325] The second light, passing through the second position P2 of the semi-transparent mirror HM, is used as a reference light to illuminate the reference surface 23 and is reflected. Here, the incident angle and reflection angle of the reference light relative to the reference surface 23 are the aforementioned angle θ2.

[0326] Subsequently, the reference light involved in the second light reflected by the reference surface 23 is incident again on the first position P1 of the semi-transparent mirror HM. For the reference light involved in the second light incident on the first position P1 of the semi-transparent mirror HM, a portion (half) passes through the semi-transparent mirror HM and is emitted from the second surface HMb toward the second imaging system 4B, while the remaining portion (half) is reflected by the first surface HMa and is emitted toward the first projection system 2A.

[0327] On the other hand, the second light incident from the second projection system 2B onto the second position P2 of the semi-transparent mirror HM and reflected by the second surface HMb is used as measurement light to illuminate the workpiece W and then reflected. Here, the angle of incidence and the angle of reflection of the measurement light related to the second light relative to the setting part 24 (workpiece W) are the aforementioned angle θ2.

[0328] Subsequently, the measurement light involved in the second light reflected by the workpiece W is again incident on the first position P1 of the semi-transparent mirror HM. For the measurement light involved in the second light incident on the first position P1 of the semi-transparent mirror HM, a portion (half) is reflected by the second surface HMb and emitted toward the second imaging system 4B, while the remaining portion (half) passes through the semi-transparent mirror HM and is emitted from the first surface HMa toward the first projection system 2A.

[0329] That is, at the first position P1 of the semi-transparent mirror HM, a reference light involving the second light reflected by the first surface HMa and a measurement light involving the second light transmitted to the first surface HMa are synthesized, and a reference light involving the second light transmitted to the second surface HMb and a measurement light involving the second light reflected by the second surface HMb are synthesized.

[0330] As a result, the composite light, which combines the reference light and the measurement light involved in the second light synthesis, is emitted as the output light from the first position P1 of the semi-transparent mirror HM to the second imaging system 4B and the first projection system 2A, respectively. Therefore, the "first position P1 of the semi-transparent mirror HM" constitutes the "second output unit" in this embodiment.

[0331] Among them, the composite light (reference light and measurement light) involved in the second light incident on the first projection system 2A is interrupted by the first optical isolator 12A and becomes discarded light.

[0332] On the other hand, the composite light (reference light and measurement light) involved in the second light incident on the second imaging system 4B interferes with the image sensor 70B, so the second camera 33B obtains an interference fringe image generated by the second light source.

[0333] Furthermore, the Fourier transform-based measurement method for obtaining the complex amplitude of the measurement light based on the interference fringe image of the carrier fringes generated by intentionally tilting the reference plane 23 as described above is a well-known technique (see, for example, Japanese Patent No. 6271493, paragraphs 372-377), and therefore its detailed description is omitted.

[0334] Thus, the brightness image data (brightness image data involving the first light and brightness image data involving the second light) obtained through one imaging process respectively contain the complex amplitude information of the measurement light required for three-dimensional measurement.

[0335] Furthermore, the control device 5 can calculate the phase of the measurement light of each wavelength using the Fourier transform method based on the brightness image data of the first light and the brightness image data of the second light stored in the image data storage device 54. The surface shape of the workpiece W is measured based on the obtained phase information of the two wavelengths. That is, the height at each measurement position on the surface of the workpiece W is measured. The measurement result (height data) of the workpiece W obtained in this way is stored in the calculation result storage device 55 of the control device 5. Moreover, the measurement method based on the Fourier transform method using two lights of different wavelengths, as described above, is known technology (see, for example, Japanese Patent No. 6271493), therefore its detailed description is omitted.

[0336] As detailed above, in this embodiment, the first and second beams traveling from the projection systems 2A and 2B to the imaging systems 4A and 4B are configured such that their directions (vectors) do not overlap. That is, the first and second beams incident on the interference optical system 3 do not interfere with each other and are emitted separately from the interference optical system 3 in a completely separated state.

[0337] Thus, according to this embodiment, by simply setting the incident positions and incident angles of the first and second beams relative to the interference optical system 3, the first and second beams can be completely separated and processed. Therefore, the number of optical components required for separating and converting polarized light components (P-polarized light and S-polarized light), such as polarizing beam splitters and quarter-wave plates, can be significantly reduced, resulting in a simplified structure. In particular, an optical system that eliminates the need for a quarter-wave plate, which allows polarized light components of two different wavelengths to pass in the same direction along the same optical path, can be realized.

[0338] As a result, the influence of manufacturing errors and other factors from the specified optical components can be eliminated, thereby improving measurement accuracy.

[0339] Furthermore, by using two lights with similar wavelengths as the first and second lights, the measurement range involved in three-dimensional measurement can be further expanded. In addition, since the output light involved in the first light and the output light involved in the second light can be captured simultaneously, the measurement efficiency can be improved.

[0340] Furthermore, in this embodiment, by not using a polarization image sensor as the imaging element of cameras 33A and 33B, the structure can be further simplified.

[0341] In addition to the structure of this embodiment, it can also be configured as described in the fifth embodiment above, including objective lenses L1 and L2, projection lenses L3A and L3B, and imaging lenses L4A and L4B.

[0342] Furthermore, the implementation is not limited to the descriptions of the above embodiments; for example, it can also be implemented as follows. Of course, other application examples and modifications illustrated below can also be made.

[0343] (a) In the above embodiments, specific examples of workpiece W (types of shape, size, material, etc.) are not specifically mentioned, but examples of test objects include, for instance, solder paste printed on a printed circuit board, solder bumps formed on a wafer substrate, etc. Of course, the structure can also be configured to measure different test objects. Furthermore, it can be configured such that a three-dimensional measuring device 1 is included in an inspection device that checks the quality of the test object according to a pre-set pass / fail judgment standard.

[0344] (b) The configuration of the projection systems 2A and 2B, the interference optical system 3, and the imaging systems 4A and 4B is not limited to the above-described embodiments.

[0345] (b-1) For example, in the above embodiments, the incident angle θ1 and reflection angle θ1 of the reference light related to the first light relative to the reference surface 23, the incident angle θ1 and reflection angle θ1 of the measuring light related to the first light relative to the setting part 24 (workpiece W), the incident angle θ2 and reflection angle θ2 of the reference light related to the second light relative to the reference surface 23, and the incident angle θ2 and reflection angle θ2 of the measuring light related to the second light relative to the setting part 24 (workpiece W) are set to the same angle (θ1 = θ2).

[0346] Not limited to this, it is also possible to configure the various angles θ1 involved in the first light and the various angles θ2 involved in the second light to be set to different angles.

[0347] (b-2) In the above embodiments, the structure is configured to take pictures of a workpiece W from different angles using two imaging systems 4A and 4B. Therefore, reducing the angles θ1 and θ2 relative to the axis (Z-axis) orthogonal to the workpiece W and taking pictures of the workpiece W from as close to the same angle as possible is preferred in terms of improving measurement accuracy.

[0348] (b-3) The various angles θ1 involved in the first light and the various angles θ2 involved in the second light are preferably set such that the incident angles of the first light and the second light relative to the semi-transparent and semi-reflective mirror HM are less than the critical angles of total internal reflection of the first light and the second light.

[0349] (b-4) The positions of the “first input” and “second input” of the optical unit, the positions of the “first output” and “second output” of the optical unit, and the combinations of the various angles θ1 and θ2 of the first light and the second light are not limited to the above embodiments. As long as the travel directions (vectors) of the measurement light of the first light and the measurement light of the second light do not overlap, they can be any combination.

[0350] That is, such as Figure 13 (Refer to the thick dashed line) It can also be any combination other than the case where the travel directions (vectors) of the measuring light and reference light involved in the first light toward the workpiece W and reference surface 23 overlap with those of the measuring light and reference light involved in the second light toward the workpiece W and reference surface 23.

[0351] For example, in the above embodiments, the optical paths of the first light and the second light are set to the same XZ plane, but it is not limited to this. It can also be configured such that, in a top view viewed from the Z-axis direction, at least one of the optical paths of the measuring light involving the first light toward the workpiece W and the measuring light involving the second light toward the workpiece W is set along the Y-axis direction.

[0352] In other words, it can also be configured such that at least one of the optical paths of the measuring light involved in the first light toward the workpiece W and the optical paths of the measuring light involved in the second light toward the workpiece W is set to have an inclination toward the Y-axis direction (forward or backward) relative to the Z-axis direction.

[0353] Alternatively, it can be configured such that the optical paths of the first light measuring light and the second light measuring light, which are directed toward the workpiece W, overlap in a top view viewed from the Z-axis direction, and the incident angles θ1 and θ2 of the first light measuring light and the second light measuring light are set to be different.

[0354] (c) The structures involved in the interference optical system (the specified optical system) and the optical unit are not limited to the above-described embodiments.

[0355] (c-1) For example, the optical unit is not limited to the semi-transparent mirror HM and beam splitter 20 of the above embodiments, and other optical components that can split the incident light into two beams may also be used.

[0356] (c-2) such as Figure 14As shown in (a), in the sixth embodiment described above, on the first surface 20a of the beam splitter 20, the first position 20a1 where the incident light K1 of the first light emitted from the first projection system 2A is incident and the second position 20a2 where the emitted light (the composite light of the reference light and the measurement light involved in the first light) K2 of the first light is emitted are arranged in a direction parallel to one side of the square-shaped first surface 20a.

[0357] Instead, such as Figure 14 As shown in (b), the first position 20a1 where the incident light K1 of the first light is incident and the second position 20a2 where the emitted light K2 of the first light is emitted can also be set on the first surface 20a of the beam splitter 20 to be arranged in the diagonal direction of the square-shaped first surface 20a.

[0358] Therefore, comparison Figure 14 of (a), Figure 14 From (b), we know that if the diameters (widths) of the incident light K1 and the emitted light K2 of the first light do not change, then Figure 14 The structure shown in (b) (the structure in which the first position 20a1 and the second position 20a2 are arranged diagonally on the first surface 20a) can use a smaller beam splitter 20 (α1 > α2) with a shorter length on one side of the first surface 20a. As a result, miniaturization of the device can be achieved.

[0359] Of course, not limited to the sixth embodiment (beam splitter 20) described above, in the first to fifth embodiments using a rectangular plate-shaped semi-transparent mirror HM, the first position P1 where the incident light K1 of the first light is incident and the second position P2 where the emitted light K2 of the first light is emitted can also be arranged in the diagonal direction of the semi-transparent mirror HM.

[0360] (d) The structure of the irradiation unit is not limited to the structure of the above-mentioned projection systems 2A and 2B.

[0361] (d-1) For example, in the above embodiments, a structure is illustrated in which light with wavelength λ1 = 1500 nm is irradiated from the first light projection system 2A and light with wavelength λ2 = 1503 nm is irradiated from the second light projection system 2B, but the wavelength of each light is not limited to this. However, in order to expand the measurement range, it is preferable to make the wavelength difference between the two lights smaller.

[0362] (d-2) Furthermore, the light-emitting units 11A and 11B in the above embodiments are configured to emit laser light using a laser light source, but are not limited to this, and other structures may also be used. Any structure capable of emitting light with high coherence (coherent light) that can at least produce interference is acceptable.

[0363] For example, it can also be configured to combine incoherent light sources such as LED light sources with bandpass filters or special filters that allow only specific wavelengths to pass through in order to improve coherence and emit coherent light.

[0364] (e) The structures of the imaging unit and imaging element are not limited to the embodiments described above.

[0365] (e-1) For example, in the above embodiments, a CCD image sensor is listed as an example of the light-receiving element array 71, but the light-receiving element array 71 is not limited to this, and may also have a semiconductor element structure such as a CMOS image sensor.

[0366] (e-2) The polarization image sensors 70A and 70B described in the above embodiments are configured to include a light-receiving element array 71, a polarizer array 72, and a microlens array 73, but are not limited thereto. For example, the microlens array 73 may be omitted.

[0367] (e-3) The arrangement of polarizers 75 in the polarizer array 72 is not limited to the above embodiments.

[0368] For example, in the above embodiments, four types of polarizers 75a, 75b, 75c, and 75d, which are configured such that the set angles of the transmission axis differ by 45°, are arranged in a predetermined order, but they may also be arranged in a different order.

[0369] Alternatively, it can be configured as three polarizers with different transmission axis angles arranged in a predetermined order. For example, it can also be configured as three polarizers with transmission axis angles differing by 60° or 45°, arranged in a predetermined order.

[0370] (f) The structure involved in the phase shift that changes the phase difference between the reference light and the measurement light is not limited to the above embodiments.

[0371] (f-1) In the above embodiments, the configuration is such that by using polarization image sensors 70A and 70B as imaging elements of cameras 33A and 33B, multiple sets of brightness data required for measuring the height of workpiece W based on the phase shift method are simultaneously acquired by taking a single shot by each camera 33A and 33B. In the polarization image sensors 70A and 70B, four types of polarizers 75 with a set angle of 45° different from the transmission axis are arranged in a predetermined manner and corresponding to each light-receiving element 74.

[0372] Not limited to this, for example, a conventional image sensor that omits the polarizer array 72 may be used as the imaging element instead of polarizer image sensors 70A and 70B, and the imaging systems 4A and 4B may have a polarizer capable of changing the transmission axis direction.

[0373] Through this polarizing plate, the components of the first and second light rays, which are converted into circularly polarized light by the quarter-wave plates 31A and 31B, can be selectively transmitted, and the reference light components and measurement light components of the first and second light rays with different rotation directions can interfere with a specific phase.

[0374] More specifically, the first imaging system 4A may also be configured to include: a quarter-wave plate 31A that converts the composite light (reference light component and measurement light component) involving the first light into circularly polarized light; a rotating first polarizing plate that selectively allows a predetermined component of the light transmitted through the quarter-wave plate 31A to pass through (causing interference between the reference light and the measurement light); and a first camera 33A that captures the light transmitted through the first polarizing plate. The second imaging system 4B may also be configured to include: a quarter-wave plate 31B that converts the composite light (reference light component and measurement light component) involving the second light into circularly polarized light; a rotating second polarizing plate that selectively allows a predetermined component of the light transmitted through the quarter-wave plate 31B to pass through (causing interference between the reference light and the measurement light); and a second camera 33B that captures the light transmitted through the second polarizing plate.

[0375] Alternatively, the following structure can be used: the reference surface 23 is moved in the normal direction of the reference surface 23 by means of a piezoelectric element, so that the optical path length is physically changed, thereby performing phase shift.

[0376] However, the structure that performs phase shift by changing the transmission axis direction of the polarizer and the structure that performs phase shift by moving the reference plane 23 require multiple shots to acquire all the image data required for three-dimensional measurement. Therefore, from the viewpoint of shortening the shooting time, a structure that can capture all image data in one shot, as described in the above embodiments, is more preferable. Furthermore, in the above structures, not only is the measurement time longer, but the measurement accuracy may also be reduced due to the influence of air fluctuations, vibrations, etc.

[0377] (f-2) In the above embodiments, when measuring the height of workpiece W by the phase-shifting method, the phase-shifting method is performed on the brightness image data of four sets of interference lights with a phase difference of 90° (brightness image data involving the first light and brightness image data involving the second light) for the first light and the second light, respectively. However, the number of phase shifts and the amount of phase shift are not limited to these. For example, the height measurement of workpiece W based on the phase-shifting method can also be performed on the brightness image data of three sets of interference lights with a phase difference of 120° (or 90°).

[0378] (f-3) can also be applied to structures that are measured in three dimensions using methods different from phase-shifting and Fourier transform methods.

[0379] (g) In the seventh embodiment described above ( Figure 12In the example, the tilt angle θ3 of the reference plane 23 is expressed as the rotation angle about the Y-axis. However, this tilt angle is an example. The actual tilt angle can also be tilted to the angle about the Z-axis, or tilted to the combined angle about the Y-axis and about the Z-axis.

[0380] 1…Three-dimensional measuring device;

[0381] 2A…First projection system;

[0382] 2B…Second projection system;

[0383] 3…interference optical systems;

[0384] 4A…First Shooting System;

[0385] 4B…Second shooting system;

[0386] 5…control devices;

[0387] 11A…First light-emitting part;

[0388] 11B…Second light-emitting part;

[0389] 21, 22… polarizing plates;

[0390] 23…Reference plane;

[0391] 24…Setup Department;

[0392] 31A…1 / 4 wavelength plate;

[0393] 31B…1 / 4 wavelength plate;

[0394] 33A…First Camera;

[0395] 33B…Second camera;

[0396] 70A…polarization image sensor;

[0397] 70B…polarization image sensor;

[0398] HM… Semi-transparent and semi-reflective mirror;

[0399] W…workpiece.

Claims

1. A three-dimensional measuring device, characterized in that, have: A defined optical system having an optical unit capable of splitting a defined incident light into two beams, the optical system being able to use at least a portion of the split beam as a measurement beam to illuminate an object under test, and use at least a portion of the other beam as a reference beam to illuminate a reference surface, and to combine and emit at least a portion of the measurement beam reflected by the object under test and at least a portion of the reference beam reflected by the reference surface. The first irradiation unit is capable of emitting a first wavelength of light incident on the first input portion of the optical unit; The second irradiation unit is capable of emitting a second wavelength of light that is incident on the second input section of the optical unit; The first imaging unit is capable of capturing a predetermined output light related to the first light emitted from the first output section of the optical unit by the first light incident on the first input section; The second imaging unit is capable of capturing a predetermined output light related to the second light emitted from the second output of the optical unit by the second light incident on the second input unit; as well as An image processing unit is capable of performing a three-dimensional measurement of the object under test based on image data acquired by the first and second imaging units. The measurement light involved in the first light from the optical unit towards the object under test and the measurement light involved in the second light from the optical unit towards the object under test have different travel directions, and the reference light involved in the first light from the optical unit towards the reference surface and the reference light involved in the second light from the optical unit towards the reference surface have different travel directions. The measurement light involved in the first light reflected by the object under test and directed toward the optical unit and the measurement light involved in the second light reflected by the object under test and directed toward the optical unit have different travel directions, and the reference light involved in the first light reflected by the reference surface and directed toward the optical unit and the reference light involved in the second light reflected by the reference surface and directed toward the optical unit have different travel directions. The optical unit is configured to combine a portion of the measurement light involved in the first light reflected by the object under test and a portion of the reference light involved in the first light reflected by the reference surface and emit them from the first output unit, and to combine a portion of the measurement light involved in the second light reflected by the object under test and a portion of the reference light involved in the second light reflected by the reference surface and emit them from the second output unit.

2. The three-dimensional measuring device according to claim 1, characterized in that, have: A first polarizing plate is disposed between the optical unit and the reference surface, allowing the first polarized light to pass through; A second polarizing plate is disposed between the optical unit and the object to be tested, allowing the second polarized light to pass through; A first quarter-wavelength plate, disposed between the first output section of the optical unit and the first imaging unit, converts the first polarized light and the second polarized light involved in the first light into circularly polarized light, respectively. A second 1 / 4 wavelength plate, disposed between the second output section of the optical unit and the second imaging unit, converts the first polarized light and the second polarized light involved in the second light into circularly polarized light, respectively.

3. The three-dimensional measuring device according to claim 1 or 2, characterized in that, When viewed from a predetermined axial direction orthogonal to the object under test, the optical paths of the first light beam from the optical unit toward the object under test and the optical paths of the second light beam from the optical unit toward the object under test are symmetrical about this axis. and, When viewed from a predetermined axial direction orthogonal to the reference plane, the optical paths of the reference light involving the first light from the optical unit toward the reference plane and the optical paths of the reference light involving the second light from the optical unit toward the reference plane are symmetrical about this axis.

4. The three-dimensional measuring device according to any one of claims 1 to 3, characterized in that, The angle of incidence of the first light relative to the object under test and the angle of incidence of the second light relative to the object under test are the same. and, The angle of incidence of the reference light of the first light relative to the reference surface and the angle of incidence of the reference light of the second light relative to the reference surface are the same.

5. The three-dimensional measuring device according to any one of claims 1 to 4, characterized in that, The optical unit is a semi-transparent and semi-reflective mirror.

6. The three-dimensional measuring device according to claim 1, characterized in that, The device is configured to perform three-dimensional measurement of the object under test by using the Fourier transform method to obtain the complex amplitude of the measurement light based on the image data, wherein the image data is obtained by capturing carrier fringes generated by positioning the optical unit in a predetermined positional relationship with the reference plane.

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