JP2005077390A - Method and instrument for measuring position and attitude - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a position and attitude measuring instrument capable of measuring precisely six axes of a position and an attitude of a measuring face at the same time. <P>SOLUTION: A plurality of grooves is formed on the measuring face 4 to serve as a diffraction part 7. Light is emitted from a light source 3 toward the diffraction part 7 to detect primary diffraction light generated by the diffraction part 7, by photoreception elements 1, 2. A relative distance between the photoreception elements 1, 2 and the measuring face is changed to detect the diffraction lights at least twice. A computation processing part 61 computes the center brightness position of the diffraction light detected in each of the relative distances, optical axes of the diffraction lights incident into the photoreception elements 1, 2 are found respectively based on the center brightness positions, and the position and attitude of the measuring face 4 are calculated based on the two obtained optical axes and an irradiation (emission) axis of the light source 3. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a position and orientation measurement method and a position and orientation measurement apparatus that measure the position and orientation of a micro surface.

  In recent years, the use of micromachine parts called micromachines and MEMS (Micro Electro Mechanical System) has been advanced. For example, a micromirror array called DMD (Digital Micro-mirror Device) used for a projector is well known. The DMD is a structure in which a small mirror with a side of several microns is laid out by the MEMS technology (see, for example, Patent Document 1).

  Conventional projectors project images by transmitting light from a light source through a transmissive liquid crystal panel. However, since the transmittance of the liquid crystal is not so high, a large light source is required for use in a high-brightness projector, which has been a bottleneck in reducing the size.

  On the other hand, in a projector using a DMD, the inclination of a minute mirror is controlled independently to control whether or not the light reflected by the mirror is projected onto a screen through a lens. By repeating this tilt control several thousand times per second, the image projected on the screen appears as a smooth moving image to human eyes. Since the projector using DMD is a reflection type, it is possible to provide a small projector with high brightness and very little light loss.

  As another application example of the DMD, the DMD is used for an optical switch for optical communication (see, for example, Patent Document 2). In this method, light output from an optical fiber is reflected by a micromirror and incident on another optical fiber, and the optical fibers can be directly optically connected without electrical conversion. In this case, if the accuracy of the angle reflected by the micromirror is poor, all the emitted light cannot be made incident on the optical fiber, and the light coupling efficiency deteriorates. Therefore, high accuracy is required for the position and inclination (hereinafter referred to as posture) of a micromirror whose side is about several hundred microns.

JP 2003-215495 A JP 2003-43384 A

  By the way, the method of measuring the position and orientation can be roughly divided into a triangulation method and a confocal method as measurement principles. In the triangulation method, for example, the measurement surface 100 is irradiated with light such as laser light as shown in FIG. 2A, and the reflected light is detected by the light receiving element 101. When the measurement surface 100 moves in parallel with respect to the light source 102 from α to β, the light receiving point at the light receiving element 101 moves from A ′ to B ′. The principle of the triangulation method is to obtain the displacement amount α-β from the movement amount A′-B ′. However, even when the inclination of the measurement surface 100 changes as in β ′ in FIG. 2B, the light receiving point position on the light receiving element 101 moves similarly from A ′ to B ′. Therefore, there is a drawback that the position and orientation cannot be measured separately.

On the other hand, the confocal method is a method of measuring the position of the measurement surface from the in-focus position. FIG. 3 is a diagram for explaining the principle of the confocal method. The light emitted from the light source 110 passes through the half mirror 111 and the lens 112 and is then collected on the measurement surface 113. At this time, the light is condensed so that the following expression (1) is satisfied. S is the distance from the light source 110 to the lens 112, and f is the focal length of the lens 112.
1 / S + 1 / S ′ = 1 / f (1)

  The light reflected by the measurement surface 113 is transmitted again through the lens 112 and then reflected by the half mirror 111 in the direction of the pinhole 114. In the confocal method, the pinhole 114 is disposed at a position optically conjugate with the light source 110. That is, the pinhole 114 is disposed at a position where the distance from the principal point on the half mirror side of the lens 112 is S. And the light which permeate | transmitted this pinhole 114 is detected with the photon detection element 115, for example, the photodiode which is a photoelectric conversion element.

4A and 4B are diagrams for explaining a position detection method using a confocal method, where FIG. 4A is an optical path diagram, and FIG. 4B is a diagram illustrating a relationship between a focus position and a received light amount detected by the light detection element 115. is there. An optical path 116 indicated by a solid line in FIG. 4A indicates an optical path when the measurement surface 113 is at the in-focus position as in FIG. It is known that the hole diameter d of the pinhole 114 can be appropriately set from Expression (2).
d = 0.61 × (wavelength of light source light) / (numerical numerical aperture of lens) (2)

  When the measurement surface 113 is at the in-focus position, the light is condensed at the pinhole position, so that the amount of light received by the light detection element 115 is the largest value Lmax. On the other hand, when the lens 112 in FIG. 3 is moved in the direction of the half mirror 111, the focus position is shifted from the measurement surface 113 as an optical path 117 as indicated by a dotted line in FIG. Therefore, the light is not collected at the pinhole position, much light is blocked by the shielding portion of the pinhole 114, and only a small part of the light is detected by the light detection element 115. As a result, the received light amount L ′ at that time is a smaller value than Lmax.

  Further, when the lens 112 is moved to the measurement surface side, the amount of received light is similarly small. That is, the amount of light received detected by the light detection element 115 is the largest when the measurement surface 113 is at the in-focus position. From this, by searching for the maximum value Lmax of the amount of received light when the lens 112 is moved by a piezo element or the like, the in-focus position can be known and the position of the measurement surface 113 can be measured. .

  In such a confocal method, even if the measurement surface 113 is inclined, the position of the measurement surface 113 can be measured as long as the reflected light is within an angle range where the reflected light is incident on the lens 112. This is a very superior advantage compared to the triangulation method, but there is a disadvantage that the posture cannot be measured at the same time even if the displacement of one axis can be measured.

  Thus, when the measurement is performed by either the triangulation method or the confocal method alone, the position and orientation cannot be measured simultaneously. In addition, if both measurement methods are used simultaneously, it is possible to measure the position and orientation at the same time. However, since a plurality of measurement devices are required, the measurement device itself is increased in size and applied to a micromachine having a size of several millimeters or less. It was very difficult. Furthermore, there is a drawback that the measuring device is expensive.

In the position and orientation measurement method according to the first aspect of the present invention, light is applied to the diffraction portion provided on the measurement surface, and the measurement is performed based on the light irradiation direction and the emission direction of the diffracted light of a predetermined order emitted from the diffraction portion. It is characterized by measuring the position and orientation of the surface.
According to a second aspect of the present invention, there is provided a position / orientation measurement apparatus comprising: a diffractive part provided on a measurement surface; a light source that irradiates light to the diffractive part; It is characterized by comprising direction detection means and calculation means for calculating the position and orientation of the measurement surface based on the emission direction detected by the emission direction detection means and the light irradiation direction of the light source.
According to a third aspect of the present invention, in the position / orientation measurement apparatus according to the second aspect, the diffractive portion includes one or a plurality of grooves, and the emission direction detecting means detects the emission direction of the diffracted light included in the reflected light of the diffractive portion. To do.
According to a fourth aspect of the present invention, in the position / orientation measurement apparatus according to the second aspect, the diffractive portion includes one or a plurality of slits, and the emission direction detecting means detects the emission direction of the diffracted light included in the transmitted light of the diffractive portion. To do.
According to a fifth aspect of the present invention, in the position / orientation measuring apparatus according to any one of the second to fourth aspects, the emission direction detecting means includes a photoelectric conversion element that receives diffracted light, and a relative distance between the photoelectric conversion element and the measurement surface. And a distance changing means for changing the light intensity, and detecting the emission direction based on the light receiving position of the diffracted light and the change in the relative distance.
According to a sixth aspect of the present invention, in the position / orientation measuring apparatus according to the fifth aspect, the photoelectric conversion element and the light source are arranged on the same substrate and integrated.

  According to the present invention, the position and orientation of the measurement surface can be easily and simultaneously measured by detecting the diffracted light from the diffraction section provided on the measurement surface.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing a schematic configuration of a position and orientation measurement apparatus according to the present invention. In FIG. 1, reference numeral 4 denotes a measurement surface whose position and orientation are to be measured, and corresponds to the surface of a micro component such as a MEMS. A diffraction portion 7 is formed on the measurement surface 4. The diffracting unit 7 reflects and diffracts the irradiated light, and is composed of, for example, one or a plurality of grooves. In the example shown in FIG. 1, a plurality of grooves 71 extending in the x-axis direction are formed on the measurement surface 4.

  Reference numeral 3 denotes a light source that emits laser light, and the laser light from the light source 3 is applied to the diffraction section 7 provided on the measurement surface 4. The diffracted light generated by the diffraction unit 7 is detected by the light receiving elements 1 and 2 arranged along the y-axis direction with the light source 3 interposed therebetween. For the light receiving elements 1 and 2, for example, a CCD camera is used. The light receiving elements 1 and 2 are held by the moving device 5. The moving device 5 can be moved up and down in the z direction by an actuator such as a piezo element. The detection results of the light receiving elements 1 and 2 are input to the arithmetic processing unit 61 of the control device 6, and arithmetic processing relating to the position and orientation is performed. Further, the moving device 5 is controlled by the movement control unit 62 of the control device 6.

  FIG. 5 is a diagram illustrating the diffracted light generated by the diffracting unit 7. As shown in FIG. 5 (a), when the light L from the light source 3 is irradiated onto the diffractive portion 7 of the measurement surface 4 from above, the light is reflected with a predetermined intensity distribution as schematically shown in FIG. 5 (b). The In general, it is known that light transmitted through a plurality of slits interfere with each other to generate an intensity distribution, which is called Fraunhofer diffraction. In the present invention, it is used that the same intensity distribution is obtained when the reflected light from the minute grooves 71 interfere with each other.

  Light having a reflection angle equal to the incident angle is called zero-order light. Light having strong intensity generated on both sides is called first-order diffracted light, and sequentially called second-order diffracted light and third-order diffracted light. Further, these lights other than the 0th-order light are collectively referred to as high-order diffracted light. In the present invention, since these diffracted lights are used as probes, the diffracted lights used as probes are hereinafter referred to as diffracted light probes.

  Note that when zero-order light is used as the diffracted light probe, it becomes difficult to measure the rotation in the plane of the measurement surface 4. This is because, when the measurement surface 4 in which the groove 71 is formed is illuminated almost vertically upward (incident angle ≈ 0 degrees), even if the measurement surface 4 is rotated in the plane, it is only rotated around the 0th order light as the central axis. This is because there is no change in the emission direction of the zero-order light. Therefore, it is desirable to use higher-order diffracted light after the first-order diffracted light as the diffracted light probe, and the higher the order, the easier it is to ensure posture measurement accuracy. However, since the light intensity of the higher order diffracted light is weaker, it is necessary to consider the SN ratio with respect to the electric noise of the photoelectric conversion element used for the light receiving elements 1 and 2. In the present embodiment, a case where first-order diffracted light is used as a diffracted light probe will be described.

<Description of measurement method>
Next, a measurement method will be described. First, as shown in FIG. 6, the light receiving elements 1 and 2 are arranged at _a predetermined position z _a with respect to the measurement surface 4 by the moving device 5. The light source 3 illuminates the diffractive portion 7, and the first-order diffracted light emitted from the diffractive portion 7 is detected by the light receiving elements 1 and 2. When a CCD camera is used as the light receiving elements 1 and 2, an image as shown in FIG. 7 is obtained. 7A shows an image obtained by the light receiving element 1, and FIG. 7B shows an image obtained by the light receiving element 2. The circular areas 10 and 11 are bright areas that receive the first-order diffracted light, and the luminance distribution is such that the luminance becomes higher at the centers 10a and 11a of the areas. Hereinafter, the centers 10a and 11a are referred to as luminance center positions 10a and 11a.

  The arithmetic processing unit 61 calculates the coordinates of the luminance center positions 10a and 11a using the luminance data of the images obtained by the light receiving elements 1 and 2. For example, when a CCD camera is used, the coordinate values in the CCD camera coordinate system of the luminance center positions 10a and 11a are obtained by calculating the center of gravity using the luminance value of each pixel and the pixel coordinates. Since the CCD camera coordinate system is a local coordinate whose origin is, for example, the lower left corner of the imaging area, a parameter for converting the local coordinate into a world coordinate whose origin is the apparatus reference position is obtained in advance by calibration. Then, the local coordinate values of the luminance center positions 10a and 11a are converted into coordinate values on the world coordinates using the above parameters.

Then, by moving the light receiving elements 1, 2 in the z-direction by the moving device 5 is disposed at a position z _b. As in the case of the position z _a , the coordinate values in the world coordinate system of the luminance center positions 10a and 11a of the images obtained by the light receiving elements 1 and 2 are obtained. Here, the world coordinate values of the luminance center positions 10a and 11a obtained at the detector position z _a are (x ₁ , y ₁ , z ₁ ), (x ₂ , y ₂ , z ₂ ), and the detector position z. The world coordinate values of the luminance center positions 10a and 11a obtained at _b are expressed as (x ₁ ′, y ₁ ′, z ₁ ′), (x ₂ ′, y ₂ ′, z ₂ ′).

<< Calculation of position >>
FIG. 8 shows measured values of the luminance center positions 10a and 11a. A straight line passing through the world coordinate values (x ₁ , y ₁ , z ₁ ), (x ₁ ′, y ₁ ′, z ₁ ′) of the luminance center position 10 a is the optical axis J 1 of the first-order diffracted light detected by the light receiving element 1. The linear equation of the optical axis J1 can be obtained from the measured coordinate values (x ₁ , y ₁ , z ₁ ), (x ₁ ′, y ₁ ′, z ₁ ′). Similarly, the straight line passing through the world coordinate values (x ₂ , y ₂ , z ₂ ) and (x ₂ ′, y ₂ ′, z ₂ ′) of the luminance center 11 a is the light of the first-order diffracted light detected by the light receiving element 2. The axis J2 is represented, and a linear equation of the optical axis J2 can be obtained from the measured coordinate values (x ₂ , y ₂ , z ₂ ), (x ₂ ′, y ₂ ′, z ₂ ′).

  As shown in FIG. 8, the intersection J3 of these two optical axes J1 and J2 is on the center line 72 of the minute groove group constituting the diffractive portion 7. Therefore, the x coordinate, the y coordinate, and the z coordinate of the intersection of the center line 72 and the incident optical axis J4 of the light source 3 can be calculated from the linear equation of the optical axes J1 and J2. However, even when the measurement surface 4 moves in the longitudinal direction (x direction) of the minute groove 71, the coordinate value (x, y, z) of the intersection J3 does not change, and the same coordinate value is obtained. You need to be careful.

《Calculation of posture》
Next, a method for calculating the posture will be described. First, as shown in FIG. 9, a bisector J5 (hereinafter referred to as a diffracted optical axis bisector) between the optical axis J1 and the optical axis J2 of the diffracted light is obtained. When light from the light source 3 is incident on the measurement surface 4 perpendicularly, the incident optical axis J4 and the normal line n of the measurement surface 4 coincide, but as shown in FIG. . In this case, based on the law of reflection, the angle (incident angle) θ1 between the incident optical axis J4 and the normal line n, and the angle (exit angle) θ2 between the normal line n and the diffracted optical axis bisector J5, Are equal.

  That is, by obtaining a bisector between the diffracted optical axis bisector J5 and the incident optical axis J4, an equation of the normal n of the measurement surface 4 can be obtained. Since the surface perpendicular to the normal line n is the measurement surface 4, the inclinations θx, θy, and θz of the measurement surface 4 can be calculated from the equation of the normal line n. Since the linear equation on the world coordinate of the incident optical axis J4 is known by prior calibration, the posture (by calculating the equation of the diffracted optical axis bisector J5 from the linear equation of the optical axis J1 and the optical axis J2) θx, θy, θz) can be calculated.

  In the measurement method described above, in order to measure the linear equation of the diffracted optical axes J1, J2, the moving device 5 changes the relative distance between the light receiving elements 1, 2 and the measurement surface 4 to change the diffracted optical axes J1, J2. Although two of the points are measured, of course, measurement accuracy can be improved by measuring a plurality of points in each of the diffracted optical axes J1 and J2 and calculating the diffracted optical axes J1 and J2.

  As described above, according to the measurement method of the present embodiment, it is possible to simultaneously measure six axes that combine the position (x, y, z) and the posture (θx, θy, θz). Furthermore, since it is only necessary to form one or a plurality of minute grooves 71 constituting the diffraction section 7 on the measurement surface 4, even a minute measurement surface such as a DMD can be easily measured.

  Note that, as described above, when the measurement surface 4 moves in the longitudinal direction of the groove 71, no change is observed in the position measurement value, and thus the displacement of the measurement surface 4 cannot be measured. Therefore, measurement can be made possible by configuring the diffractive portion 7 with a pair of micro groove groups 73 and 74 orthogonal to each other as shown in FIG. Of course, even if the angle at which the minute groove groups 73 and 74 intersect is not orthogonal, if the angle is known, the measurement can be performed by correcting based on the angle.

  When a pair of minute groove groups 73 and 74 are used, four light receiving elements 31, 32, 33, and 34 are disposed around the light source 3 as shown in FIG. Although not shown, these light receiving elements 31 to 34 are provided in the moving device 5 (see FIG. 1), and can be moved together in the z direction. In the apparatus shown in FIG. 10, for example, using a pair of light receiving elements 31 and 34, the equation of the center line 73 a of the minute groove group 73 is obtained in the same manner as the center line 72 described above. Further, using the remaining pair of light receiving elements 32 and 33, an equation of the center line 74a of the minute groove group 74 is obtained.

  The position (x, y, z) of the measurement surface 4 can be obtained by obtaining the intersection of the center lines 73a and 74a from the equation of the center line 73a and the equation of the center line 74a. Further, by obtaining an equation of a plane including the center line 73a and the center line 74a from the equation of the center line 73a and the equation of the center line 74a, a plane constituted by the two center lines 73a and the center line 74a. The posture (θx, θy, θz) of the measurement surface 4 can be obtained from the equation That is, regardless of the direction in which the measurement surface 4 moves, the six axes of position (x, y, z) and posture (θx, θy, θz) can be measured simultaneously.

<Optimization of intensity distribution>
Next, a method for optimizing the shape of the diffracted light probe, that is, the intensity distribution will be described. In the optimization, the following three items are examined.

  The first is sharpening of the intensity distribution. When the intensity distribution is gentle, it is difficult to detect the intensity change as the measurement surface 4 is slightly displaced, and the measurement accuracy deteriorates. This is similar to the fact that in the case of a surface shape measuring instrument using a mechanical probe, a fine surface shape cannot be accurately measured if the probe tip is thick.

  The second is to improve the SN ratio. Since the intensity of the diffracted light becomes weaker as the higher order component is used, the diffracted light intensity is increased by using the diffracted light having the lowest order as much as possible, as in the case of the first embodiment.

  The third is to secure an interval between adjacent diffracted lights. As described above, when a CCD camera is used as the light receiving elements 1 and 2, it can be dealt with by devising the brightness center calculation. For example, when a PSD (Position Sensitive Detector) is used for the light receiving elements 1 and 2, for example. If the adjacent diffracted light enters the PSD together with the diffracted light probe, the luminance center cannot be measured accurately. Therefore, it is necessary to configure the diffractive portion 7 so as to ensure a sufficient interval between adjacent diffracted lights.

  When setting the diffraction part 7 mentioned above, it is necessary to optimize the groove width of the groove 71, the space | interval of the groove | channel 71, and the number of the grooves 71 so that these three items may be satisfy | filled. As described above, it is known that the intensity distribution of light emitted from one or a plurality of grooves can be modeled as Fraunhofer diffraction. Using this diffracted light distribution model, (a) the SN ratio is improved when the width of each minute groove 71 is narrowed, and (b) the distance between adjacent diffracted lights is widened when the distance between the minute grooves 71 is narrowed. (C) It can be seen that the intensity distribution is sharpened when the number of the minute grooves 71 is increased.

  FIG. 11 illustrates how the intensity distribution changes according to the procedures (a) to (c). In the case of the intensity distribution as shown in FIG. 11A, when the groove width is narrowed, it changes as shown in FIG. 11B and the SN ratio is improved. Further, when the groove interval is narrowed, the peak interval is widened as shown in FIG. 11 (c), and the peak is sharpened as shown in FIG. 11 (d) by increasing the number of grooves.

  For example, a theoretical value and an actual measurement value of the diffracted light intensity distribution when a laser (He-Ne laser, wavelength: 633 nm) is irradiated onto the diffractive portion 7 having a width of 2 μm, an interval of 5 μm, and 41 fine grooves 71. Is shown in FIG. In FIG. 12, the broken line is the measured value, and it has been confirmed that the theoretical value (solid line) is in good agreement with the Fraunhofer diffraction theory that indicates the diffracted light intensity distribution after transmission through the transmission-type slit.

  Further, when the groove cross-sectional shape is rectangular, the theoretical value is better matched. The actual measurement values shown in FIG. 12 show an example in which the Si substrate is deep-etched with an ICP-RIE (reactive ion etching) apparatus so that the cross-sectional shape is rectangular. For example, when the microgroove 71 is formed by anisotropic etching using a Si substrate, the cross-sectional shape becomes a triangle, so that the diffracted light intensity distribution obtained is strictly the theoretical value calculated from the Fraunhofer diffraction equation. Will not fit. However, it is possible to apply the above optimization flow, and it can be used as a guideline for designing a minute groove necessary for obtaining a predetermined measurement accuracy.

  Also, in order to optimize using the Fraunhofer diffraction formula, it is difficult to handle all the grooves 71 having the same width and the same groove interval. However, even if the groove width is different from one line to another, and the groove interval is different, the diffracted light intensity distribution can be simulated, and there is no problem in applying the present invention.

  In the measurement method described above, a parameter for converting the local coordinate values related to the light receiving elements 1 and 2 into the world coordinate value is obtained in advance, or an equation on the world coordinate of the incident optical axis J4 from the light source 3 is obtained. Calibration was required. However, in the apparatus shown in FIG. 13, since the light receiving elements 200 to 203 and the light source 210 are provided on the same substrate 211 and their relative positions are fixed, they are arranged on the substrate 211 with high accuracy. This facilitates calibration, and can also eliminate the need for calibration.

  In the apparatus shown in FIG. 1, it is necessary to define world coordinates by separately preparing a high-precision stage and to obtain the coordinates of the light receiving elements 1 and 2 within the world coordinates. On the other hand, in the apparatus of FIG. 13, for example, the world coordinates can be defined using the substrate surface of the substrate 211 on which the four light receiving elements 200 to 203 are mounted and the optical axis J4 of the emitted light 212 of the light source 210. . Of course, also in the apparatus of FIG. 13, the number of light receiving elements can be two as in the apparatus of FIG.

  In the above-described embodiment, the reflection type diffraction unit 7 is used. However, as shown in FIG. 14, a transmission type diffraction unit 700 may be used. A plurality of slits 701 are formed in the diffractive portion 700 provided on the measurement surface 4, and light is emitted from the light source 3 provided below the measurement surface 4 to the diffractive portion 700, and the transmitted light is received by the light receiving element. 1 and 2 are detected. 1 and 14, the relative distance is changed by moving the light receiving elements 1 and 2 with respect to the measurement surface 4, but conversely, the relative distance may be changed by moving the measurement surface 4. .

  In the above-described embodiment, the position and orientation measurement of a micro component such as MEMS has been described as an example. However, the measurement method of the present invention can measure the straightness of movement of a high-precision moving stage of a sequential exposure apparatus (stepper) or a robot joint. It can be widely applied to applications such as angle measurement where multiple axes of position and orientation (tilt) are separated with high accuracy. In addition, the present invention is not limited to the above embodiment as long as the characteristics of the present invention are not impaired.

  In the correspondence between the embodiment described above and the elements of the claims, the arithmetic processing unit 61 is an arithmetic unit, the light receiving elements 1 and 2, the moving device 5 and the arithmetic processing unit 61 are an emission direction detecting unit, and a moving device. 5 and the movement control unit 62 constitute distance changing means, respectively.

It is a schematic diagram which shows schematic structure of the position and orientation measuring apparatus by this invention. It is a figure explaining a triangulation method, (a) shows the case where the measurement surface 4 moves in parallel, (b) shows the case where the measurement surface 4 inclines, respectively. It is a figure explaining the principle of a confocal method. It is a figure explaining the position detection method by a confocal method, (a) is an optical path figure, (b) is a figure which shows the relationship between a focus position and light reception amount. It is a figure explaining the diffracted light which the diffraction part 7 generate | occur | produces, (a) shows incident light, (b) shows diffracted light. It is a figure explaining a measuring method. It is a figure which shows the image by the light receiving elements 1 and 2, (a) shows the image by the light receiving element 1, (b) shows the image by the light receiving element 2, respectively. It is a figure which shows the positional relationship of the measured value of the luminance center position 10a, 11a. FIG. 5 is a diagram showing a relationship between an incident optical axis J4, a diffraction axis bisector J5, and a normal line n of a measurement surface 4; It is a figure which shows the structure of the light receiving element at the time of forming the micro groove groups 73 and 74 in a measurement surface. It is a figure which shows the optimization procedure of intensity distribution, (a) shows the diffracted light intensity distribution before optimization, (b)-(d) shows the diffracted light intensity distribution in each step of optimization. It is a figure which shows the theoretical value and measured value of diffracted light intensity distribution by Fraunhofer diffraction theory. It is a figure which shows the light receiving elements 200-203 and the light source 210 which are arrange | positioned on the same board | substrate 211. FIG. It is a schematic diagram which shows schematic structure of the position and orientation measurement apparatus at the time of using the transmissive | pervious diffraction part 700. FIG.

Explanation of symbols

1, 2, 31 to 34, 200 to 203 Light receiving element 3,210 Light source 4 Measurement surface 5 Moving device 6 Control device 6
7,700 Diffraction unit 10a, 11a Luminance center position 61 Arithmetic processing unit 62 Movement control unit 71 Groove 73, 74 Micro groove group 701 Slit J1, J2 Optical axis J3 Intersection J4 Incident optical axis J5 Diffraction axis 2 bisector

Claims (6)

  Irradiating light to a diffraction part provided on a measurement surface, and measuring the position and orientation of the measurement surface based on the irradiation direction of the light and the emission direction of a predetermined order of diffracted light emitted from the diffraction part A position and orientation measurement method characterized by A diffraction part provided on the measurement surface;
A light source for irradiating the diffraction part with light;
An emission direction detecting means for detecting an emission direction of diffracted light of a predetermined order emitted from the diffraction unit;
A position / orientation measurement apparatus comprising: an operation unit that calculates the position and orientation of the measurement surface based on the emission direction detected by the emission direction detection unit and the light irradiation direction of the light source. In the position and orientation measurement apparatus according to claim 2,
The diffraction part is composed of one or a plurality of grooves,
The position / orientation measurement apparatus characterized in that the emission direction detecting means detects an emission direction of the diffracted light included in the reflected light of the diffraction unit. In the position and orientation measurement apparatus according to claim 2,
The diffraction part is composed of one or a plurality of slits,
The position / orientation measurement apparatus characterized in that the emission direction detecting means detects an emission direction of the diffracted light included in the transmitted light of the diffraction unit. In the position and orientation measurement apparatus according to any one of claims 2 to 4,
The emission direction detecting unit includes a photoelectric conversion element that receives the diffracted light, and a distance changing unit that changes a relative distance between the photoelectric conversion element and the measurement surface, and a light reception position of the diffracted light and the relative distance. A position and orientation measurement apparatus that detects the emission direction based on a change in the position. In the position and orientation measurement apparatus according to claim 5,
The position / orientation measurement apparatus characterized in that the photoelectric conversion element and the light source are arranged on the same substrate and integrated.

Images