JP2013174577A - Surface shape measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface shape measuring device having a configuration more simple than a conventional device.SOLUTION: A surface shape measuring device 10 is equipped with: a light source 12 which irradiates a surface to be measured 26 with light; a light receiver 20 which receives reflection light from the surface to be measured 26; and an arithmetic section 22. Further, the device is also equipped with a first optical element G1 having a first grating 28a and a second optical element G2 having a second grating 28b which are provided on an optical path between the light source 12 and the surface to be measured 26. The arithmetic section 22 calculates angle θ of the surface to be measured 26 based on the first grating 28a and the second grating 28b, the positions of the first grating 28a and the second grating 28b, and brightness corresponding to the positions.

Description

  The present invention relates to a surface shape measuring apparatus.

  Conventionally, a surface shape measuring apparatus for measuring the surface shape of a measurement object is known. As such a device, a device that projects a pattern such as moire fringes on a surface to be measured is known. This apparatus captures an image of the pattern projected on the surface to be measured and calculates the shape of the surface to be measured from the image data. For example, in Non-Patent Document 1, a pattern reflected on a surface to be measured is captured using two cameras, and a normal vector of the surface to be measured is calculated based on imaging data of each camera. .

  Patent Document 1 discloses a surface shape measuring device that displaces a screen having a pattern to be projected onto a surface to be measured in the vertical and horizontal directions. The apparatus extracts a data set that minimizes the difference in pixel values from a plurality of imaging data acquired for each displacement. Furthermore, the path of light received by the image sensor is estimated based on screen position information when the extracted data is captured.

JP 2008-39767 A

MCKnauer and 2 others, “Phase measuring deflectometry: a new approach to measure specular free-form surfaces”, light in production engineering Measurement Conference Report (Proc. Optical Metrology in Production Engineering) (USA), The International Society for Optical Engineering (SPIE), 2004, Vol. 5457, p. 366-376 A. Livnat, O. Kafri, “Moire technique for measuring liquid level”, Applied Optics, 1982, Vol. 21, Vol. 16, p. 2868-2870 K Patorski, M Kujawinska, "Handbook of the Moire Fringe Technique", 1st edition, Elsevier, January 1993, p. 295- 322

  By the way, when moving the screen in the vertical and horizontal directions, means for moving the screen in the biaxial direction is required. Therefore, an object of the present invention is to provide a surface shape measuring device having a simpler configuration than the conventional one.

  The present invention relates to a surface shape measuring apparatus. The apparatus includes a light source that irradiates light to a surface to be measured and a light receiver that receives reflected light from the surface to be measured. A first optical element provided on an optical path between the light source and the surface to be measured, and having a first grating; and an optical path between the light source and the surface to be measured, and a second grating. A second optical element. Furthermore, a first acquisition means for acquiring the light reception luminance of the light receiver as the first luminance when the first optical element is at the first position and the second optical element is at the second position; and And a second acquisition means for acquiring the light reception luminance of the light receiver as the second luminance when the second optical element is at the fourth position. Further, the angle of the surface to be measured based on the first grating, the second grating, the first luminance, the second luminance, the first position, the second position, the third position, and the fourth position. And an arithmetic unit for calculating. Furthermore, in this configuration, the distance from the first position to the second position is smaller than the distance from the third position to the fourth position.

  In the above invention, the distance from the first position to the second position is a first distance, the distance from the third position to the fourth position is a second distance, and the first lattice is The first grating is a one-dimensional grating in which parallel lines are arranged at a first pitch, the second grating is a one-dimensional grating in which parallel lines are arranged at a second pitch, and the first grating is parallel to the second grating. Preferably it is. In this case, it is preferable that the calculation unit calculates an angle of the surface to be measured based on the first pitch, the second pitch, the first distance, and the second distance.

  In the above invention, a third optical element having a third grating provided on an optical path between the light source and the surface to be measured and arranged with parallel lines orthogonal to the first grating at a third pitch. A fourth optical element provided on an optical path between the light source and the surface to be measured and having a fourth grating in which parallel lines orthogonal to the second grating are arranged at a fourth pitch. Is preferred. Further, third acquisition means for acquiring the light reception luminance of the light receiver as the third luminance when the third optical element is at the fifth position and the fourth optical element is at the sixth position, and the third optical element is the first 7th position, It is suitable to provide the 4th acquisition means which acquires the light-receiving brightness of the above-mentioned photoreceiver as the 4th brightness when the 4th optical element is the 8th position. Further, the calculation unit is based on the third grid, the fourth grid, the third brightness, the fourth brightness, the fifth position, the sixth position, the seventh position, and the eighth position, It is preferable to calculate the angle of the surface to be measured. In this case, it is preferable that the distance from the fifth position to the sixth position is larger than the distance from the seventh position to the eighth position.

  In the above invention, the distances from the first position to the fifth position, the sixth position, the seventh position, and the eighth position are the pitch Λ of the grating moving on the optical path, and the distance from the first position, respectively. It is preferably larger than the value Λ / 2γ using the aperture angle γ of the light receiver. Furthermore, it is preferable that the distances from the eighth position to the first position, the second position, the third position, and the fourth position are each greater than the value Λ / 2γ.

  Further, in the above invention, third acquisition means for acquiring the light reception luminance of the light receiver as the fifth luminance when the first optical element is at the ninth position and the second optical element is at the tenth position; It is preferable that a fourth obtaining unit obtains the light reception luminance of the light receiver as the sixth luminance when the optical element is in the eleventh position and the second optical element is in the twelfth position. In this case, the ninth position is located in a direction orthogonal to the parallel lines of the first grating from the first position, and the tenth position is parallel lines of the second grating from the second position. The eleventh position is located in a direction perpendicular to the parallel line of the first grating from the third position, and the twelfth position is located from the fourth position to the It is preferable that it is located in a direction orthogonal to the parallel lines of the second grating.

  Further, the surface shape measuring apparatus according to the present invention includes a light source that irradiates a surface to be measured, a light receiver that receives reflected light from the surface to be measured, and an optical path between the light source and the surface to be measured. A first optical element having a first grating, and a second optical element having a second grating provided on an optical path between the light source and the surface to be measured. Furthermore, a plurality of the light receivers corresponding to a plurality of distances from the first optical element to the second optical element, and displacement means for changing the distance from the first optical element to the second optical element. And calculating the angle of the surface to be measured based on the change period of the received light brightness acquired by the first grating, the second grid, and the fifth acquiring means with respect to the distance. And an arithmetic unit.

  In the above invention, the first grating is a one-dimensional grating in which parallel lines are arranged at a first pitch, and the second grating is a one-dimensional grating in which parallel lines are arranged at a second pitch. Is preferred. In this case, it is preferable that the first grating is parallel to the second grating, and the calculation unit calculates an angle of the surface to be measured based on the first pitch and the second pitch.

  In the above invention, a third optical element having a third grating provided on an optical path between the light source and the surface to be measured and arranged with parallel lines orthogonal to the first grating at a third pitch. A fourth optical element provided on an optical path between the light source and the surface to be measured and having a fourth grating in which parallel lines orthogonal to the second grating are arranged at a fourth pitch. Is preferred. Furthermore, a displacement means for changing the distance from the third optical element to the fourth optical element, and a plurality of distances corresponding to a plurality of distances from the light receiver to the first optical element to the second optical element It is suitable to provide the 6th acquisition means which acquires the received light intensity. In this case, the calculation unit may calculate an angle of the surface to be measured based on a change period with respect to the distance of the light reception luminance acquired by the third grating, the fourth grating, and the sixth acquisition unit. Is preferred.

  Further, in the above invention, the fifth acquisition means is configured such that the distances from the first optical element to the third optical element and the fourth optical element are the pitch Λ of the grating moving on the optical path and the light reception, respectively. A light receiving luminance is obtained when the value is larger than the value Λ / 2γ using the aperture angle γ of the device, and the sixth obtaining means obtains the light from the fourth optical element to the first optical element and the second optical element. It is preferable to obtain the received light luminance when the distances are respectively larger than the value Λ / 2γ.

  In the above invention, it is preferable that the second optical element is disposed adjacent to the third optical element.

  In the above invention, the distance from the first optical element to the second optical element is preferably not more than a value Λ / 2γ using an aperture angle γ of the light receiver and a pitch Λ of the grating. .

  In the above invention, the distance from the third optical element to the fourth optical element is preferably not more than a value Λ / 2γ using an aperture angle γ of the light receiver and a pitch Λ of the grating. .

  In the above invention, it is preferable that the first pitch is equal to the second pitch.

  In the above invention, it is preferable that the third pitch is equal to the first pitch, and the third pitch is equal to the fourth pitch.

  Moreover, in the said invention, it is suitable that the opening angle (gamma) of the said light receiver is 10 mrad or less.

  Further, in the above invention, the light receiver includes a first light receiver and a second light receiver, and the arithmetic unit calculates an angle of the surface to be measured based on light reception luminance of the first light receiver and the second light receiver. It is preferable to calculate.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the surface shape measuring apparatus of a simpler structure than before.

It is a figure which illustrates the surface shape measuring apparatus which concerns on this Embodiment. It is a figure explaining the opening angle of the image pick-up device. It is a figure explaining the means to obtain | require the angle difference between different to-be-inspected surfaces. It is a figure explaining the means to obtain | require the angle difference between different to-be-inspected surfaces. It is a figure explaining the means to obtain | require the angle difference between different to-be-inspected surfaces. It is a figure explaining the means to obtain | require the angle difference between different to-be-inspected surfaces. It is a figure explaining the means to specify reflected light. It is a figure explaining the means to specify reflected light. It is a figure explaining the means to obtain | require the angle difference between different to-be-inspected surfaces. It is a figure explaining the means to obtain | require the angle difference between different to-be-inspected surfaces. It is a figure explaining the means to obtain | require the angle difference between different to-be-inspected surfaces. It is a figure which illustrates the flowchart of surface shape measurement. It is a figure which illustrates the imaging data of a to-be-inspected surface. It is a figure which illustrates the flowchart of surface shape measurement. It is a figure which illustrates the flowchart of surface shape measurement. It is a figure which illustrates the flowchart of surface shape measurement. It is a figure which illustrates the flowchart of surface shape measurement. It is a figure which illustrates the normal vector distribution of a to-be-inspected surface. It is a figure which illustrates the three-dimensional shape of the calculated to-be-inspected surface. It is a figure explaining the means to specify the position of a reflective point. It is a figure explaining the means to specify the position of a reflective point. It is a figure explaining the arithmetic processing using Hilbert transform. It is a figure explaining the phase difference of the luminance change according to an incident angle. It is a figure which illustrates the attenuation process of the amplitude of a brightness | luminance. It is a figure which illustrates the surface shape measuring apparatus which concerns on other embodiment. It is a figure which illustrates the surface shape measuring apparatus which concerns on other embodiment. It is a figure which illustrates the surface shape measuring apparatus which concerns on other embodiment. It is a figure which illustrates the surface shape measuring apparatus which concerns on other embodiment.

  A surface shape measuring apparatus according to the present embodiment is illustrated in FIG. The surface shape measuring apparatus 10 includes a light source 12, a grating element G, a grating element stage 16, a measurement object stage 18, an imager 20, and an information processor 22.

  The light source 12 irradiates light toward the measurement surface 26 of the measurement object 24. In order to prevent shadows from appearing when the image pickup device 20 images the measurement target surface 26, the light source 12 is preferably a light source that can irradiate the entire measurement target surface 26. For example, the light source 12 can be composed of a surface light source.

  The grating element G is an optical element including the optical grating 28. The lattice element G is obtained by forming a lattice pattern by evaporating a non-translucent material on the surface of a translucent substrate such as glass or quartz. The lattice pattern of the lattice element G is preferably set according to the characteristics of light emitted from the light source 12 used in the surface shape measuring apparatus 10 and the reflection characteristics of the measurement object 24. For example, the lattice element G can be a Ronchi lattice element including a one-dimensional lattice 28 in which parallel lines are arranged at a pitch of 59 lines / cm (150 lines / inch).

  A plurality of grating elements G are provided. For example, the grating elements G1 and G2 are provided on the optical path between the light source 12 and the measured surface 26. The lattice patterns and pitches of the plurality of lattice elements G1 and G2 may be the same or different.

  The lattice element stage 16 is a displacement means for changing the intervals on the optical path of the plurality of lattice elements G. The grid element stage 16 may move the position of each grid element G, or may move only one of the grid elements G, and may fix the remaining grid elements G. For example, the lattice element stage 16 includes a fixed stage 30 and a moving stage 32. The moving stage 32 only needs to be movable in the uniaxial direction, and may be a uniaxial stage, for example.

  In FIG. 1, the lattice element G <b> 1 is held on the fixed stage 30, and the lattice element G <b> 2 is held on the moving stage 32. Further, the lattice element stage 16 may be fixed so that the lattices 28a and 28b of the respective lattice elements G1 and G2 are parallel, or may be fixed in a non-parallel state. As will be described later, it is preferable to hold the grating elements G1 and G2 with the gratings 28a and 28b in parallel in order to reduce the calculation load when calculating the angle change of the measured surface 26. Here, “parallel” is not limited to a perfect parallel relationship, that is, not only when the angle between the lattices is 0 °, but the effect of the angle deviation between the lattices on the angle difference obtained by measurement is substantially a problem. Including cases that do not.

  In addition, as the moving stage 32 moves, the interval between the lattice element G1 and the lattice element G2 is changed. At this time, the moving direction of the moving stage 32 may be perpendicular to the grating 28a of the grating element G1 fixed to the fixed stage 30, or may be different from the vertical direction. As will be described later, it is preferable to move the moving stage 32 in a direction perpendicular to the grating 28a in order to reduce the calculation load when calculating the angle change of the measurement surface 26. Here, the term “vertical” is not limited to the complete vertical relationship, and includes the case where the influence of the angular deviation from the vertical is not a problem with respect to the angular difference obtained by measurement.

  Returning to FIG. 1, the measurement object stage 18 is a member for fixing the measurement object 24. In order to finely adjust the initial position of the measurement object 24, a moving mechanism may be provided.

  The imaging device 20 is a device that images the measurement surface 26 of the measurement object 24. For example, as shown in FIG. 2, the imager 20 includes a light receiving surface 40 in which a plurality of light receiving elements such as a CCD sensor and a CMOS sensor are arranged in an array. Here, if light is incident on one light receiving element 34 with a wide aperture angle, the periodicity of luminance change described later may be reduced. Therefore, it is preferable to narrow down the aperture angle γ of the imager 20. For example, the opening angle γ is preferably 10 mrad or less. The imager 20 may include an angle adjustment stage or the like in order to make the reflected light from the measurement object 24 enter the light receiving element 34 through the aperture that has been narrowed down.

  The information processor 22 is connected to the grid element stage 16 and the imaging device 20. The information processor 22 is a device that performs arithmetic processing on signals sent from these devices and transmits control signals to these devices. The information processor 22 includes a storage unit 36 and a calculation unit 38.

  The storage unit 36 is a device that stores a moving pitch of the moving stage 32, image data captured by the imaging device 20, a program for performing arithmetic processing on the image data, and the like. The memory | storage part 36 should just be an apparatus which can memorize | store these information, for example, can be comprised from 1 or multiple combinations, such as ROM, RAM, EPROM, a hard disk drive.

  The calculation unit 38 performs a calculation process on the image data captured by the imaging device 20. By this calculation process, the angle between the different measured surfaces 26 is calculated. In addition, the calculation unit 38 transmits a drive signal for a predetermined movement pitch (for example, 0.1 mm) to a driving unit such as a motor (not shown) that drives the moving stage 32. The calculation unit 38 may be any device capable of performing these calculation processes, and may be configured to include, for example, a microcomputer unit.

  Next, surface shape measurement according to the present embodiment will be described. FIG. 3 illustrates a schematic diagram when light is irradiated from the light source 12 to the measurement surface 26a. The light emitted from the light source 12 is reflected by the measured surface 26 a and enters the light receiving surface 40 of the imager 20. Here, when attention is paid to the reflected light 43 received by the light receiving element 34 on the light receiving surface 40 and the incident light 42a corresponding to the reflected light 43, the incident angle and the reflection angle are equal from the law of reflection.

  Furthermore, FIG. 4 shows a schematic diagram when light is irradiated to the measured surface 26b having an angle different from that of the measured surface 26a. The angle formed between the measured surface 26a and the measured surface 26b is represented by θ. As shown in FIG. 4, the incident angle of the incident light corresponding to the reflected light 43 received by the light receiving element 34 is different between when the measurement target is the measurement target surface 26a and when the measurement target is the measurement target surface 26b. It will be different. The angle formed by the incident light 42a corresponding to the reflected light 43 and the axis along the displacement direction x of the grating element G2 when the measurement target is the measurement target surface 26a is represented by β1. Further, β2 represents an angle formed between the incident light 42b corresponding to the reflected light 43 and the axis along the displacement direction x of the lattice element G2 when the measurement target is the measurement target surface 26b. 4 and 5, it can be derived that the angle θ formed between the measured surface 26a and the measured surface 26b is equal to the half value Δβ / 2 of the difference Δβ between the angles β1 and β2 (θ = Δβ / 2). Using this relationship, the calculation unit 38 calculates the angle β between the different measured surfaces 26 by obtaining the angle β.

  Next, calculation of the angle β will be described with reference to FIG. In FIG. 6, the lattice elements G1 and G2 are arranged so that the lattices 28a and 28b of the lattice elements G1 and G2 are parallel to each other. The displacement direction of the lattice element G2 is set to be perpendicular to the lattice 28a of the lattice element G1.

  When the grating element G2 is displaced from the initial position x0, the luminance of the incident light 42 directed from the light source 12 toward the measured surface 26 changes with the displacement of the grating element G2. For example, when the position of the grating element G2 is x1, the incident light 42 is blocked by the grating element G2, and the luminance becomes a minimum value. Furthermore, as the grating element G2 is displaced in a direction away from the grating element G1, the luminance of the incident light increases. Furthermore, after taking the maximum value of the luminance, the luminance tends to decrease, and when the position of the grating element G2 becomes x2, the incident light 42 is again blocked by the grating element G2, and the luminance becomes the minimum value. . Thus, the luminance of the incident light 42 changes according to the change in the interval between the lattice elements G1 and G2. Here, as the luminance of the incident light 42 changes, the luminance of the reflected light 43 also changes. Therefore, the luminance change of the incident light 42 can be obtained based on the luminance change of the light receiving element 34 that receives the reflected light 43.

  The period L of the luminance change can be obtained from the interval between the lattice elements G1 and G2 corresponding to the adjacent minimum value or maximum value in the intensity change of the reflected light 43. Here, the following formula (1) can be derived by using the period L of the luminance change, the incident angle β, and the grating pitch Λ (of the grating element to be moved) of the grating element G2.

In Equation (1), the lattice pitch Λ can be acquired in advance. The angle β is obtained by substituting the known lattice pitch Λ and the period L acquired from the luminance change into β = tan ⁻¹ (Λ / L) obtained by modifying Equation (1) or Equation (1). Can do.

  For example, in FIG. 5, β1 is obtained from the period L1 of the luminance change of the reflected light from the measured surface 26a and the formula (1). Similarly, β2 is obtained from the period L2 of the luminance change of the reflected light from the measured surface 26b and the formula (1).

Subsequently, by obtaining the difference Δβ between the angles β1 and β2 and obtaining the half value Δβ / 2, the angle θ between the measured surfaces 26a and 26b can be obtained (Δβ / 2 = θ). Alternatively, Δβ may be directly obtained from Δβ = [tan ⁻¹ (Λ / L ₁ ) −tan ⁻¹ (Λ / L ₂ )] using the period L1 and the period L2.

  Note that, in order to obtain the period L1 and the period L2, it is necessary to obtain the luminance change curve in the lower part of FIG. In order to obtain an accurate change curve, it is preferable to obtain a luminance plot according to the displacement x based on a so-called sampling theorem. That is, it is preferable to perform sampling at an interval smaller than ½ of the period of the change curve. Specifically, since the period L of the change curve is obtained by L = Λ / tan β, the sampling interval is preferably less than Λ / 2 tan β. That is, it is preferable that Δx <Λ / 2 tan β be set for the movement pitch Δx in the x direction of the grating element stage 16. Here, since the value of β is not known at the time of measurement, the maximum value of β acquired at the previous measurement may be used.

  Although only incident light 42 is shown in FIG. 6, incident light 142 other than incident light 42 can be considered as incident light that can take the angle β and the luminance distribution in the lower stage of FIG. 6. For example, when considering a concave surface and a convex surface having the same curvature, the incident light incident on one surface may become the incident light 42 and the incident light incident on the other surface may become the incident light 142. In order to accurately measure the shape of the measurement object, it is preferable to specify whether the incident light incident on the measurement surface is the incident light 42 or the incident light 142. Therefore, as shown in FIG. 8, the positions of the grid element G1 and the grid element G2 may be shifted to perform measurement again.

  First, the relative positions of the lattice element G1 and the lattice element G2 are changed along a direction different from the displacement direction x. For example, the lattice element G2 is moved in a direction orthogonal to the displacement direction x with respect to the lattice element G1. The moving distance is preferably less than the lattice pitch Λ, for example, Λ / 4 is preferable. When the lattice element G2 is displaced and then displaced in the x direction, the timing at which the incident light 42 and the incident light 142 are blocked by the lattice element G2 is different. Along with this, the phases of the respective luminance change curves are shifted. For example, as shown in the lower part of FIG. 8, the change curve 146 of the incident light 42 has a leading phase and the change curve 148 of the incident light 142 has a lagging phase as compared to the change curve 144 before shifting the grating element G2. Based on this phase change, it is possible to specify whether the incident light corresponding to the reflected light 43 is the incident light 42 or the incident light 142.

  As shown in FIG. 9, when the lattice 28b of the lattice element G2 is not parallel to the lattice 28a of the lattice element G1, it is preferable to obtain the angle β in consideration of the angular difference. Here, in FIG. 9, the displacement direction of the lattice element G2 is a direction perpendicular to the lattice 28a of the lattice element G1. When the angle of the lattice 28b of the lattice element G2 with respect to the lattice 28a of the lattice element G1 is expressed by ε, the following formula (2) can be derived.

  In the above formula (2), the lattice pitch Λ and the angle ε can be obtained in advance by actual measurement or the like. Therefore, the angle β can be obtained by substituting these values and the obtained period L into Equation (2).

  Also, as shown in FIG. 10, when the displacement direction of the lattice element G2 is different from the perpendicular direction to the lattice 28a of the lattice element G1, the angle β is obtained in consideration of the angular difference between the vertical direction and the displacement direction. Is preferred. When the angle between the perpendicular of the lattice element G1 to the lattice 28a and the axis along the displacement direction of the lattice element G2 is represented by η, the following formula (3) can be derived.

  In the above formula (3), the lattice pitch Λ and the angle η can be obtained in advance by actual measurement or the like. Therefore, the angle β can be obtained by substituting these values and the obtained period L into Equation (3).

  In addition, as shown in FIG. 11, when the lattice elements G1 and G2 are not parallel to each other, and the displacement direction of the lattice element G2 is different from the direction perpendicular to the lattice 28a of the lattice element G1. Therefore, it is preferable to obtain the angle β in consideration of these angular differences. From FIG. 11, the following formula (4) can be derived.

  As described above, the lattice pitch Λ, the angle ε, and the angle η can be obtained in advance by actual measurement or the like. Therefore, the angle β can be obtained by substituting these values and the obtained period L into Equation (4).

  Next, the measurement process of the measured surface 26 in the surface shape measuring apparatus 10 will be described. The surface shape measurement process is roughly divided into a reference surface data acquisition step S100 (FIGS. 12 and 14), a data acquisition step S200 (FIGS. 15 and 16) of the surface 26 to be measured, and a comparison step S300 (FIG. 17). ). In addition, you may perform process S200 before process S100.

In step S100, the calculation unit 38 acquires reference plane data whose surface shape is known. First, as shown in FIG. 1, the lattice elements G1 and G2 are arranged on the lattice element stage 16 so that the lattice patterns of the lattice elements G1 and G2 are parallel to the Z axis (S101). As shown in FIGS. 3 to 5, the angle difference θ _xy between the reference surface and the measured surface 26 in the XY cross section can be obtained by making the lattice pattern parallel to the Z axis. Further, a standard material having a reference surface is fixed to the measurement object stage 18 (S102). Next, the calculation unit 38 transmits a control signal to the moving stage 32 to move the position of the lattice element G2 to the initial position x0 (S104).

  Subsequently, light is emitted from the light source 12. Here, the light output from the light source 12 reaches the reference plane via the lattice elements G1 and G2. At this time, as shown in FIG. 13, moiré fringes due to the shift of the lattice patterns of the lattice elements G1 and G2 are projected onto the reference plane. The imager 20 images the reference plane (S106). The imaging data is stored in the storage unit 36.

Next, the calculation unit 38 determines whether or not the lattice element G2 has reached a predetermined end point position x _max (S108). If not reached, the predetermined movement pitch Δx-divided lattice element G2 is moved. (S110). Further, step S106 is repeated until the end point position _xmax is reached.

When the end point position _xmax is reached, the calculation unit 38 obtains the luminance change of the imaging data for each coordinate point. As shown in FIG. 13, the imaging data is processed so that data of an arbitrary coordinate point can be extracted by two axes of the s axis and the t axis. Calculation unit 38 calls the luminance I _xy in the initial coordinates (s0, t0) (s0, t0, x0) ··· I xy (s0, t0, x max) from the storage unit 36 (S112). Further, the luminance change period L1 _xy is obtained from the luminance change corresponding to the change of x (S114).

Further, as described above, the calculation unit 38 uses the period L1 _xy and the lattice pitch Λ of the lattice element G2 and, if necessary, the angle ε and angle η as described above, the angle β1 _xy (s0, t0 in the XY section). ) Is obtained (S116). Further, the calculation unit 38 determines whether or not the coordinates to be calculated have reached the end point coordinates (sn, tn) (S118). If not reached, the coordinates are changed (S120), and the angle β1 _xy (sk, tk) is calculated until the end point position is reached.

Next, as illustrated in FIG. 14, the calculation unit 38 obtains an angle β1 _xz in the XZ cross section orthogonal to the XY cross section. First, the lattice elements G1 and G2 are arranged on the lattice element stage 16 so that the lattice patterns of the lattice elements G1 and G2 are parallel to the Y axis (S122). Next, the calculation unit 38 transmits a control signal to the moving stage 32 to move the position of the grating element G2 to the initial position x0 (S124). Hereinafter, similarly to S106 to S110, the imaging unit 20 until it reaches the end position x _max to image the moiré fringes of the reference surface (S126~S130). The imaging data is stored in the storage unit 36.

Subsequently, the calculation unit 38 obtains a luminance change of the imaging data for each coordinate point. Calculation unit 38 calls the luminance I _xz in the initial coordinates (s0, t0) (s0, t0, x0) ··· I xz (s0, t0, x max) from the storage unit 36 (S132). Further, the luminance change period L1 _xz is obtained from the luminance change corresponding to the change of _x (S134).

Further, as described above, the calculation unit 38 uses the period L1 _xz and the lattice pitch Λ of the lattice element G2 and, if necessary, the angle ε and angle η as described above, the angle β1 _xz (s0, t0 in the XZ section). ) Is obtained (S136). Further, the calculation unit 38 determines whether or not the coordinates to be calculated have reached the end point coordinates (sn, tn) (S138). If not reached, the coordinates are changed (S140), and the angle β1 _xz (sk, tk) is calculated until the end point position is reached.

Next, as illustrated in FIGS. 15 and 16, the calculation unit 38 acquires data of the measurement target surface 26 of the measurement object 24 in step S <b> 200. First, the operator arranges the lattice elements G1 and G2 on the lattice element stage 16 so that the lattice pattern of the lattice elements G1 and G2 is parallel to the Z axis (S201). Further, the measurement object 24 is fixed to the measurement object stage 18 (S202). Subsequently, light is irradiated from the light source 12 to the measurement surface 26 via the lattice elements G1 and G2. Hereinafter, in the same manner as the acquisition of image data of the reference surface, imaging the surface to be measured 26 every movement pitch Δx from the initial position x0 of the grating G2 to the end position x _max (S204-S210). Furthermore, the calculation unit 38 calculates the luminance change period L2 _xy (sk, tk, sk) from the luminance I _xy (sk, tk, X0)... I _xy (sk, tk, x _max ) at the coordinates (sk, tk) of the imaging data. tk). Furthermore, the angle β2 _xy (sk, tk) of the XY cross section corresponding to the cycle L2 _xy (sk, tk) is calculated. This is performed from the initial coordinates (s0, t0) to the end coordinates (sn, tn) (S212-220).

Next, the lattice elements G1 and G2 are arranged on the lattice element stage 16 so that the lattice patterns of the lattice elements G1 and G2 are parallel to the Y axis (S222). Subsequently, light is irradiated from the light source 12 to the measurement surface 26 via the lattice elements G1 and G2. Hereinafter, in the same manner as the acquisition of image data of the reference surface, imaging the surface to be measured 26 every movement pitch Δx from the initial position x0 of the grating G2 to the end position x _max (S224-S230). Further, the calculation unit 38 calculates the luminance change period L2 _xz (sk, tk, sk) from the luminance I _xz (sk, tk, X0)... I _xz (sk, tk, x _max ) at the coordinates (sk, tk) of the imaging data. tk). Further, the angle β2 _xz (sk, tk) of the XZ section corresponding to the cycle L2 _xz (sk, tk) is calculated. This is performed from the initial coordinates (s0, t0) to the end coordinates (sn, tn) (S232-240).

Next, in step S300 (FIG. 17), the calculation unit 38 determines the angle θ _xy of the measured surface 26 with respect to the reference plane in the XY cross section and the measured surface 26 with respect to the reference plane in the XZ cross section. _{Is obtained} for each coordinate point (s, t). The calculation unit 38 includes an angle β1 _xy (s0, t0) corresponding to the initial coordinates (s0, t0) of the reference surface and an angle β2 _xy (s0, t0) corresponding to the initial coordinates (s0, t0) of the measured surface 26. ) From the storage unit 36 (S302). Next, the calculation unit 38 obtains a difference Δβ _xy between the angle β1 _xy (s0, t0) and the angle β2 _xy (s0, t0). Further, Δβ _xy / 2 is obtained and set as an angle θ _xy (s0, t0) (S304). Subsequently, the calculation unit 38 determines whether or not the coordinates to be calculated are end point coordinates (sn, tn) (S306). When the end point coordinates have not been reached, the calculation unit 38 changes the coordinates (S308), and obtains the angle difference θ _xy (sk, tk) until the end point coordinates are reached.

Next, the calculation unit 38 obtains the angle θ _xz of the surface to be measured 26 with respect to the reference plane in the XZ plane for each coordinate point (s, t). The calculation unit 38 calculates the angle β1 _xz (s0, t0) corresponding to the initial coordinates (s0, t0) of the reference surface and the angle β2 _xz (s0, t0) corresponding to the initial coordinates (s0, t0) of the measured surface 26. ) From the storage unit 36 (S310). Next, the calculation unit 38 obtains a difference Δβ _xz between the angle β1 _xz (s0, t0) and the angle β2 _xz (s0, t0). Further, Δβ _xz / 2 is obtained and set as an angle θ _xz (s0, t0) (S312). Subsequently, the calculation unit 38 determines whether or not the coordinates to be calculated are end point coordinates (sn, tn) (S314). If the end point coordinates have not been reached, the calculation unit 38 changes the coordinates (S316) and obtains the angle difference θ _xz (sk, tk) until the end point coordinates are reached.

  As described above, the angle θ of the measured surface 26 with respect to the reference surface is obtained for all coordinates. The computing unit 38 calculates the surface shape of the measured surface 26 based on the angle θ. For example, as shown in FIG. 18, the calculation unit 38 obtains a normal vector distribution of each coordinate based on the angle θ. Further, as shown in FIG. 19, the three-dimensional shape of the measurement target surface 26 is calculated by using this normal vector distribution by using a known method, for example, Frankot-Chelappa algorithm.

  In the measurement method described above, only the calibration of the camera (imaging device) and the reference plane needs to be performed, and it is not necessary to determine the position of the Ronchi grating that forms the moire fringes. Therefore, unlike the prior art, there is no need to perform calibration for determining the positions of a plurality of cameras with respect to the reference plane and calibration for determining the positions of the liquid crystal display with respect to the cameras. In addition, when using a plurality of cameras, calibration such as brightness adjustment between the cameras is necessary to compare the captured image data with each other. However, in the above measurement method, measurement can be performed with only one camera. is there. Therefore, calibration such as brightness adjustment between cameras is not necessary.

When calculating the angle difference θ _xy (sk, tk) or θ _xz (sk, tk), the calculation unit 38 overlaps the reflection point on the reference surface and the reflection point on the surface to be measured, as shown in FIG. The calculation is performed under the assumption that However, as shown in FIG. 20, when the distance between the reference surface 126a and the measured surface 126b is large, the shape of the measured surface 126b can be accurately measured by performing the calculation under the above assumption. It can be difficult.

  In FIG. 20, the reference surface 126a is a flat surface, and the measured surface 126b is a curved surface. The reflection point of the reflected light 130a is the reflection point 132a on the reference surface 126a, and the reflection point 134a on the measured surface 126b. The reflection point 134a is located at a position shifted in the y ′ direction shown in FIG. 20 with respect to the reflection point 132a. On the other hand, if the calculation is performed under the assumption that the reflection point on the reference surface and the reflection point on the surface to be measured overlap, the calculation is performed assuming that the positions of the reflection point 134a and the reflection point 132a are equal in the y ′ direction. Done. That is, the reflection point 134a is treated as the point 136a below the reflection point 132a. Similarly, for the reflected lights 130b to 130d, the reflection points 134b to 134d are treated as points 136b to 136d below the reflection points 132b to 132d, respectively. As a result of the reflection point being treated as a point at a position different from the actual reflection point, the shape formed by connecting the normal vectors at each reflection point may be significantly different from the surface to be measured.

  Therefore, when the distance between the reference surface 126a and the measured surface 126b is long, an actual reflection point may be obtained. A configuration for obtaining an actual reflection point is shown in FIG. The surface shape measuring apparatus 10 includes two imagers 120a and 120b.

Here, a reflection point corresponding to the reflected light 130 a received by the predetermined light receiving element 122 a ₁ of the imager 120 a is represented by a reflection point 134. In addition, incident light that is incident on the reflection point 134 and that corresponds to the reflected light 130a is represented by incident light 138a. Furthermore, an angle of incident light 138a (hereinafter simply referred to as an incident angle) with respect to the displacement direction x of the grating element G2 is an angle β _1a , and an angle of reflected light 130a with respect to the reference surface 126a (hereinafter simply referred to as a reflection angle) is an angle β. Represented by _2a .

A light receiving element of the imager 120b that receives the reflected light 130b from the reflection point 134 is represented by a light receiving element 122b ₁ . Further, incident light that is incident on the reflection point 134 and that corresponds to the reflected light 130b is represented by incident light 138b. Further, the incident angle of the incident light 138b is represented by an angle β _1b , and the reflection angle of the reflected light 130b is represented by an angle β _2b . In this case, as shown in FIG. 21, the angle β _M formed by the incident light 138a and the incident light 138b is equal to the angle β _C formed by the reflected light 130a and the reflected light 130b.

The calculation unit 38 specifies the position of the reflection point 134 using the above relationship. Description will be given of a case where a predetermined light-receiving element 122a ₁ of the imaging device 120a to identify the position of the reflection point 134 of the reflected light 130a that is received. As described above, since the aperture angle of the imaging device 120a is narrowed, the reflection angle β _2a of the reflected light 130a received by the light receiving element 122a ₁ is known. Further, by performing the above-described calculation, the incident angle β _1a of the incident light 138a corresponding to the reflected light 130a can be obtained.

Further, the calculation unit 38 obtains the reflection angle β _2bk of the reflected light 130b received by the arbitrary light receiving element 122b _k of the imaging device 120b and the incident angle β _1bk of the incident light 138b corresponding to the reflected light 130b. Next, the calculation unit 38 obtains an angle β _M formed by the incident light 138a and the incident light 138b and an angle β _C formed by the reflected light 130a and the reflected light 130b. _{Specifically, β M = β 1a + β} 1bk, by performing calculation between _{β C = β 2a -β 2bk,} β M, obtaining the beta _C. Further, the calculation unit 38 compares the angle β _M with the angle β _C. If β _M = β _C, it is recognized that the reflected light 130a and the reflected light 130b are reflected from the same reflection point 134. Therefore, the intersection of the two is obtained and set as the position of the reflection point 134. If β _M ≠ β _C , the light receiving element 122b _k of the imager 120b is changed to another light receiving element, and the above calculation is performed again.

  After obtaining the reflection point 134, the calculation unit 38 specifies the reflection point 132 of the reference surface 126a having the same y′-axis coordinate as the reflection point 134. Further, the angle difference θ between the minute surface including the reflection point 134 and the minute surface including the reflection point 132 is obtained. When the reference surface 126a is a plane parallel to the y ′ axis, the step of obtaining the reflection point of the reference surface 126a corresponding to the reflection point 134 may be omitted.

  According to the above embodiment, even a curved surface having a large curvature can be accurately obtained. In the conventional measurement method and the embodiment in FIG. 1, the curved surface capable of measuring the shape is limited to a curved surface having a relatively small curvature with a radius of curvature of 100 mm or more. Even a curved surface having a curvature can be obtained accurately.

In the above-described embodiment, when obtaining the angle β, each value of the luminance I (s0, t0, x0)... I (sn, tn, _xmax ) may be corrected. As shown in the upper part of FIG. 22, when the moving pitch Δx of the lattice element G2 is a large value, the luminance change plot is discrete, and it may be difficult to accurately detect the minimum value or the maximum value. In this case, the luminance change period L cannot be obtained accurately, and it may be difficult to calculate the accurate angle β. On the other hand, when the movement pitch Δx is reduced, another problem that the measurement time increases is caused. Therefore, it is preferable to perform Hilbert transform on the luminance data so that the angle β can be calculated without reducing the movement pitch Δx.

  When the luminance I (x) at an arbitrary coordinate (sk, tk) is subjected to Hilbert transform, the phase φ of the luminance change can be obtained as in the following formula (5).

  In Equation (5), H represents an Hilbert transform operator, and Im represents an imaginary part. A graph of the phase change of the luminance I (x) converted by the equation (5) is shown in the lower part of FIG. In this graph, the vertical axis is the phase, and the horizontal axis is the displacement x of G2 with respect to the lattice element G1. In this graph, the value is added as it is without returning to 0 when the phase exceeds 2π. In the lower graph of FIG. 22, the line connecting the plots can be approximated to a linear function. Here, when the phase changes from 0 to 2π, the amount of change of x is equal to the period L. That is, if the slope of the approximated linear function is ξ, ξ × L = 2π. Further, from the formula (1), since L = Λ / tan β, the above formula can be expressed as the following formula (6).

  As described above, since the lattice pitch Λ is known, the angle β can be obtained by substituting the slope ξ of the straight line obtained by the Hilbert transform into the above equation (6).

  Further, as will be described below, the amplitude of the luminance received by the image pickup device 20 is attenuated as the distance between the grid element G1 and the grid element G2 increases. Therefore, it is preferable to determine the change range of the interval between the lattice elements G1 and G2 in consideration of the attenuation tendency of the amplitude.

  As shown in FIG. 2, light beams having various incident angles are incident on the light receiving element 34 in the range of the opening angle γ. That is, the luminance of the light receiving element 34 is a superposition of the luminances of these rays. As shown in FIG. 23, these light beams have a slight phase difference due to the difference in incident angles. As will be described below, as the distance between the grating element G1 and the grating element G2 increases, the influence of this phase difference increases, and the luminance amplitude attenuates.

  The intensity (luminance) of the light imaged on the light receiving element 34 can be expressed as the following formula (7).

  Here, when β >> φ and φ≈0, tan (β + φ) can be expressed as the following formula (8).

  Substituting equation (8) into equation (7) yields equation (9).

The intensity (luminance) waveform of Equation (9) is shown in FIG. In the graph of FIG. 24, the position of the lattice element G1 is the origin, and the displacement of the lattice element G2 relative to the lattice element G1 is represented by x. The amplitude of intensity attenuates as the distance between the grating elements G1 and G2 increases. The position x _D where the amplitude of the intensity becomes 0 is a position where the sin term of the formula (9) becomes 0, so that x _D = Λ / 2γ from πγX / Λ = π / 2. For this reason, it is preferable to set the change range of the interval between the lattice elements G1 and G2 so as to include a range of x _D = Λ / 2γ or less.

  In the above-described embodiment, a one-dimensional lattice is used as the lattice element G. However, the present invention is not limited to this. For example, as shown in FIG. 25, lattice elements G10 and G12 provided with two-dimensional lattices 28c and 28d in which parallel lines extend vertically and horizontally (Y-axis direction and Z-axis direction) may be used. Here, the pitch Λ1 of the parallel lines in the vertical direction (Z-axis direction) is preferably different from the pitch Λ2 of the parallel lines in the horizontal direction (Y direction). In this embodiment, the luminance change is affected by both the vertical pattern and the horizontal pattern. Here, due to the difference in pitch, the luminance change period due to the vertical pattern and the luminance change period due to the horizontal pattern are different. Therefore, by separating the brightness change data by frequency by Fourier transform, it is possible to separate the brightness change due to the vertical pattern and the brightness change due to the horizontal pattern.

  In the above-described embodiment, a plurality of lattice elements G are used. However, the present invention is not limited to this. For example, as shown in FIG. 26, it is possible to project moire fringes on the measured surface 26 even with a single grating element G by using a reflecting mirror 46. That is, the light source 12, the measured surface 26, and the reflecting mirror 46 are arranged so that the light from the light source 12 is reflected by the reflecting mirror 46 and the reflected light is irradiated on the measured surface 26. Next, a single grating element G is disposed on the optical path between the light source 12 and the reflecting mirror 46 and on the optical path between the reflecting mirror 46 and the surface to be measured 26. At this time, the light output from the light source 12 is reflected by the reflecting mirror 46 after passing through the lattice element G. Further, the light reflected by the reflecting mirror 46 passes through the grating element G again and reaches the measurement surface 26. The light output from the light source 12 passes through the grating element G twice, and moire fringes due to the deviation of the grating pattern between the grating element G passing through the first time and the grating element G passing through the second time are measured surface 26. Projected on. Furthermore, by moving the grating element G with respect to the reflecting mirror 46, the distance on the optical path between the grating element G passing through the first time and the grating element G passing through the second time is changed. With this change, the brightness of the reflected light received by the imager 20 changes. Thereafter, similarly to the above-described embodiment, the angle difference θ between the measured surface 26 and the reference surface can be obtained based on the luminance change.

  In the above-described embodiment, for example, as shown in FIGS. 12 to 16, after the lattice patterns of the lattice elements G1 and G2 are arranged so as to be parallel to the Z axis, the lattice element G2 is displaced, Thereafter, the lattice elements G1 and G2 are rotated by 90 ° and rearranged so as to be parallel to the Y axis, and then the lattice element G2 is displaced again. However, this is not a limitation. For example, a plurality of lattice elements whose lattice pattern is parallel to the Z axis and a plurality of lattice elements whose lattice pattern is parallel to the Y axis may be arranged on the same optical path.

  FIG. 27 illustrates lattice elements G3 and G4 in addition to the lattice elements G1 and G2 illustrated in the above embodiment. The grating elements G3 and G4 are arranged on the optical path from the light source 12 to the measured surface 26 together with the grating elements G1 and G2. The patterns of the lattices 28c and 28d of the lattice elements G3 and G4 may be the same pattern as the parallel line pattern of the lattices 28a and 28b of the lattice elements G1 and G2. Moreover, the pitch of each pattern of the grating | lattices 28a-28d may be the same, and may differ.

  The lattice elements G3 and G4 may be fixed to the lattice element stage 216. One of the lattice elements G 3 and G 4 may be fixed to the fixed stage 230 of the lattice element stage 216, and the other may be fixed to the moving stage 232. Further, the moving direction of the moving stage 232 may be the same as the moving direction of the moving stage 32.

The intervals between the lattice elements G1 to G4 are preferably as follows. That is, a set of lattice elements G1 and G2 (hereinafter referred to as a set of vertical stripes) and a set of lattice elements G3 and G4 (hereinafter referred to as a set of horizontal stripes) are separated from X _D (= Λ / 2γ). In addition, the distance between one lattice element of the set of vertical stripes and the set of horizontal stripes is set to X _D or less, and the distance between the lattice elements of the other set is separated from X _D.

As described above, when the spacing between the grid elements are separated from X _D, also by changing the relative position of the grating element to each other, it becomes zero amplitude of the reflected light intensity caused thereby. Thus, even a plurality of grating elements are lined in the same optical path, if their spacing is away from the X _D, it is displaced these lattice elements among, basically whereby reflected light luminance It does not change.

Taking advantage of this characteristic, when the interval between the lattice elements G1 and G2 is equal to or less than X _D , the interval between the lattice elements G3 and G4 with respect to the lattice elements G1 and G2 is made larger than X _D. The distance between the grating elements G3 and G4 also a larger than X _D. If ask the spacing of the grating elements G1, G2 in this state is changed within a range of X _D, without being affected by the grating element G3 and G4, measuring changes in the reflected light intensity due to distance changes of the grid elements G1 and G2 can do.

Further, when the interval between the lattice elements G3 and G4 is X _D or less, the interval between the lattice elements G1 and G2 with respect to the lattice elements G3 and G4 is set to be larger than X _D. The distance between the grating elements G1 and G2 are also a larger than X _D. If ask the spacing of the grating elements G3, G4 in this state is changed within a range of X _D, without being affected by the grating element G1 and G2, measuring changes in the reflected light intensity due to distance changes of the grid elements G3 and G4 can do.

  For example, lattice elements G1 to G4 may be arranged as shown in FIG. FIG. 28 illustrates a diagram when the lattice elements G <b> 1 to G <b> 4 are viewed from the measured surface 26 toward the light source 12. The lattice elements to be displaced are lattice elements G2 and G4. In addition, after obtaining a change in reflected light luminance due to a change in the spacing between the grating elements G1 and G2, a change in reflected light luminance due to a change in the spacing between the grating elements G3 and G4 is obtained. The displacement width of the lattice element G2 is d1.

The initial value of the interval between the grid element G1 and the grid element G2 is set to be X _D −d1 or less. The initial value of the interval between the lattice element G2 and the lattice element G3 is set so as to exceed X _D + d1. Furthermore, the initial value of the distance between the grating elements G3 and grating element G4 is set to exceed X _D.

The lattice element G2 is moved by d1 in a direction away from the lattice element G1. When the grating element G2 moves, the light receiving element 34 receives the reflected light and the information processor 22 measures the change in luminance. At this time, since the grating element G2 and the grating element G3 are separated from X _D + d1, even if the grating element G2 moves by d1, the influence of the grating element G3 is excluded when measuring the change in reflected light luminance. Further, since the lattice element G4 is separated from the lattice element G3 by _XD or more, the influence of the lattice element G4 is also eliminated.

After the lattice element G2 is displaced by d1, the lattice element G3 is moved to the lattice element G4 side. When the lattice element G3 moves, the light receiving element 34 receives the reflected light and the information processor 22 measures the change in luminance. At this time, since apart from the X _D is the grating element G2 and the lattice element G3, the influence of the grating element G2 is eliminated. Further, since the lattice element G1 is separated from the lattice element G2 by X _D + d1 or more, the influence of the lattice element G1 is also eliminated.

Based on the change in reflected light luminance based on the displacement of the grating elements G1 and G2, as shown in the flow of FIGS. 12 and 15, the angle difference θ between the reference surface and the measured surface 26 in the XY cross section. _xy can be determined. Similarly, based on the change in the reflected light luminance based on the displacement of the grating elements G3 and G4, as shown in the flow of FIGS. 14 and 16, the reference plane and the measured surface 26 in the XZ section are shown. The angle difference θ _xz can be obtained.

  DESCRIPTION OF SYMBOLS 10 Surface shape measuring apparatus, 12 Light source, 16 Grating element stage, 18 Measuring object stage, 20 Imaging device, 22 Information processing device, 24 Measuring object, 26 Surface to be measured, 28 Lattice, 30 Fixed stage, 32 Movement Stage, 34 Light receiving element, 36 Storage part, 38 Operation part, 40 Light receiving surface, 42 Incident light, 43 Reflected light, 44 Aperture, 46 Reflecting mirror, G Grating element.

Claims (16)

A light source that irradiates the surface to be measured with light;
A light receiver for receiving reflected light from the surface to be measured;
A first optical element provided on an optical path between the light source and the surface to be measured and having a first grating;
A second optical element provided on an optical path between the light source and the surface to be measured and having a second grating;
First acquisition means for acquiring, as the first luminance, the light reception luminance of the light receiver when the first optical element is in the first position and the second optical element is in the second position;
Second acquisition means for acquiring the light reception luminance of the light receiver as the second luminance when the first optical element is in the third position and the second optical element is in the fourth position;
The angle of the measured surface is calculated based on the first grid, the second grid, the first brightness, the second brightness, the first position, the second position, the third position, and the fourth position. An arithmetic unit to perform,
With
The surface shape measuring apparatus, wherein a distance from the first position to the second position is smaller than a distance from the third position to the fourth position. A distance from the first position to the second position is a first distance;
A distance from the third position to the fourth position is a second distance;
The first grating is a one-dimensional grating in which parallel lines are arranged at a first pitch;
The second grating is a one-dimensional grating in which parallel lines are arranged at a second pitch,
The first grating is parallel to the second grating;
The computing unit calculates an angle of the surface to be measured based on the first pitch, the second pitch, the first distance, and the second distance;
The surface shape measuring apparatus according to claim 1. A third optical element having a third grating provided on an optical path between the light source and the surface to be measured and arranged with parallel lines orthogonal to the first grating at a third pitch;
A fourth optical element having a fourth grating provided on an optical path between the light source and the surface to be measured and arranged with parallel lines orthogonal to the second grating at a fourth pitch;
Third acquisition means for acquiring the light reception luminance of the light receiver as the third luminance when the third optical element is in the fifth position and the fourth optical element is in the sixth position;
Fourth acquisition means for acquiring the light reception luminance of the light receiver as the fourth luminance when the third optical element is in the seventh position and the fourth optical element is in the eighth position;
With
The computing unit is configured to measure the measurement target based on the third grid, the fourth grid, the third brightness, the fourth brightness, the fifth position, the sixth position, the seventh position, and the eighth position. Calculate the angle of the face,
The surface shape measuring apparatus according to claim 2, wherein a distance from the fifth position to the sixth position is larger than a distance from the seventh position to the eighth position. The distances from the first position to the fifth position, the sixth position, the seventh position, and the eighth position are the pitch Λ of the grating moving on the optical path and the aperture angle γ of the light receiver, respectively. Is greater than the value Λ / 2γ using
The distances from the eighth position to the first position, the second position, the third position, and the fourth position are each greater than the value Λ / 2γ,
The surface shape measuring apparatus according to claim 3. Third acquisition means for acquiring the received light luminance of the light receiver as the fifth luminance when the first optical element is at the ninth position and the second optical element is at the tenth position;
Fourth acquisition means for acquiring the received light luminance of the light receiver as the sixth luminance when the first optical element is in the eleventh position and the second optical element is in the twelfth position;
With
The ninth position is located in a direction perpendicular to the parallel lines of the first grating from the first position;
The tenth position is located in a direction perpendicular to the parallel lines of the second grating from the second position,
The eleventh position is located in a direction perpendicular to the parallel lines of the first grating from the third position,
The twelfth position is located in a direction perpendicular to the parallel lines of the second grating from the fourth position.
The surface shape measuring apparatus according to claim 2. A light source that irradiates the surface to be measured with light;
A receiver that receives the reflected light from the surface to be measured;
A first optical element provided on an optical path between the light source and the surface to be measured and having a first grating;
A second optical element provided on an optical path between the light source and the surface to be measured and having a second grating;
Displacement means for changing a distance from the first optical element to the second optical element;
5 acquisition means for acquiring a plurality of received light luminances of the light receiver corresponding to a plurality of distances from the first optical element to the second optical element;
A calculation unit that calculates an angle of the surface to be measured based on a change period of the light reception luminance acquired by the first grating, the second grating, and the fifth acquisition unit with respect to the distance;
A surface shape measuring device. The first grating is a one-dimensional grating in which parallel lines are arranged at a first pitch;
The second grating is a one-dimensional grating in which parallel lines are arranged at a second pitch,
The first grating is parallel to the second grating, and the calculation unit calculates an angle of the surface to be measured based on the first pitch and the second pitch.
The surface shape measuring apparatus according to claim 6. A third optical element having a third grating provided on an optical path between the light source and the surface to be measured and arranged with parallel lines orthogonal to the first grating at a third pitch;
A fourth optical element having a fourth grating provided on an optical path between the light source and the surface to be measured and arranged with parallel lines orthogonal to the second grating at a fourth pitch;
Displacement means for changing a distance from the third optical element to the fourth optical element;
Sixth acquisition means for acquiring a plurality of received light luminances corresponding to a plurality of distances from the first optical element to the second optical element from the light receiver;
With
The calculation unit calculates an angle of the surface to be measured based on a change period of the light reception luminance acquired by the third grating, the fourth grating, and the sixth acquisition unit with respect to the distance.
The surface shape measuring apparatus according to claim 7. The fifth acquisition means is configured so that the distances from the first optical element to the third optical element and the fourth optical element are the pitch Λ of the grating moving on the optical path and the aperture angle γ of the light receiver, respectively. When it is larger than the used value Λ / 2γ, the received light intensity is obtained,
The sixth acquisition means acquires the received light brightness when the distances from the fourth optical element to the first optical element and the second optical element are each greater than the value Λ / 2γ;
The surface shape measuring apparatus according to claim 8.   The surface shape measuring apparatus according to claim 3, wherein the second optical element is disposed adjacent to the third optical element. The distance from the first optical element to the second optical element is not more than a value Λ / 2γ using an aperture angle γ of the light receiver and a pitch Λ of the grating,
The surface shape measuring apparatus according to claim 1. The distance from the third optical element to the fourth optical element is not more than a value Λ / 2γ using an aperture angle γ of the light receiver and a pitch Λ of the grating,
The surface shape measuring device according to claim 3, 4, 8 or 9.   The surface shape measuring apparatus according to claim 2, wherein the first pitch is equal to the second pitch.   The surface shape measuring apparatus according to claim 3, wherein the third pitch is equal to the first pitch, and the third pitch is equal to the fourth pitch.   The surface shape measuring apparatus according to claim 1, wherein an aperture angle γ of the light receiver is 10 mrad or less. The light receiver includes a first light receiver and a second light receiver,
The surface shape measurement apparatus according to claim 1, wherein the calculation unit calculates an angle of the surface to be measured based on light reception luminance of the first light receiver and the second light receiver.