JP2010243438A - Apparatus and method for three-dimensional shape measurement - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce measurement errors caused by principles of pattern-projection-type three-dimensional shape measurements. <P>SOLUTION: A three-dimensional shape measuring apparatus in one mode includes a projection means (13) for projecting a fringe pattern onto an object to be measurement; an imaging means (14) for acquiring luminance-change data from each position on the object to be measured, by repeatedly imaging the object to be measured, while making it change the phase of the fringe pattern projected onto the object to be measured; a control means (101) for acquiring a plurality of items of luminance change data from each position on the object to be measured, by repeatedly executing acquisition of luminance change data, while making the focal position of the fringe pattern to the object to be measured change ; a selection means (100) for performing such selection processings as to select high-reliabiility luminance change data from among the plurality of items of luminance change data acquired by the control means at each position on the object to be measured; and a shape computation means (100) for determining the coordinates of each position, indicated by luminance change data selected at each position on the object to be measured as the surface shape of the object to be measured. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a pattern projection type three-dimensional shape measuring apparatus and a three-dimensional shape measuring method using a phase shift method.

  As a method for measuring the surface shape (three-dimensional shape) of a measurement object in a non-contact manner, a pattern projection type three-dimensional shape measuring apparatus using a phase shift method is known. In this three-dimensional shape measuring apparatus, a fringe pattern having a sinusoidal intensity distribution is projected onto a measurement object, and the measurement object is repeatedly imaged while changing the phase of the fringe pattern. By applying the image (luminance change data) to a predetermined calculation formula, the phase distribution (phase image) of the stripes deformed according to the surface shape of the measurement object is obtained, and the phase image is unwrapped (phase connection) To the height distribution (height image) of the measurement object.

  Incidentally, the three-dimensional shape measuring apparatus disclosed in Patent Document 1 acquires luminance change data under two types of imaging conditions with different amounts of projection light and prevents two types of luminance change data in order to prevent measurement errors caused by saturated pixels. The brightness change data having a low contrast value is excluded from the calculation target.

JP-A-2005-214653

  However, the measurement error that occurs in the three-dimensional shape measuring apparatus is not limited to that caused by saturated pixels. In particular, measurement errors due to the principle of pattern projection type three-dimensional shape measurement need to be suppressed in order to make the pattern projection type three-dimensional shape measurement more practical.

  Accordingly, an object of the present invention is to provide a three-dimensional shape measuring apparatus and a three-dimensional shape measuring method capable of suppressing measurement errors caused by the principle of pattern projection type three-dimensional shape measurement.

  One aspect exemplifying the three-dimensional shape measuring apparatus of the present invention includes a projecting unit that projects a fringe pattern onto a measurement object, and a measurement object while changing the phase of the fringe pattern projected onto the measurement object. An imaging unit that acquires brightness change data from each position on the measurement object by repeating imaging of the object, and acquisition of the brightness change data while changing a focus position of the fringe pattern with respect to the measurement object. By repeatedly executing the control means for acquiring a plurality of brightness change data from each position on the measurement object, and selecting a reliable one from the plurality of brightness change data acquired by the control means It is represented by selection means for performing processing for each position on the measurement object, and brightness change data selected for each position on the measurement object. The height position, and a shape calculation means for calculating a surface shape of the measurement object.

  One aspect exemplifying the three-dimensional shape measurement method of the present invention includes a projection procedure for projecting a fringe pattern onto a measurement object, and a measurement object while changing the phase of the fringe pattern projected onto the measurement object. An imaging procedure for acquiring brightness change data from each position on the measurement object by repeating imaging of the object, and acquiring the brightness change data while changing a focus position of the fringe pattern with respect to the measurement object. By repeatedly executing, a control procedure for acquiring a plurality of brightness change data from each position on the measurement object, and a selection for selecting a highly reliable one from the plurality of brightness change data acquired by the control procedure It is represented by a selection procedure for performing processing for each position on the measurement object, and luminance change data selected for each position on the measurement object. The height position, and a shape calculation process for obtaining the surface shape of the measurement object.

  ADVANTAGE OF THE INVENTION According to this invention, the three-dimensional shape measuring apparatus and three-dimensional shape measuring method which can suppress the measurement error resulting from the principle of pattern projection type three-dimensional shape measurement are implement | achieved.

Configuration diagram of 3D shape measuring device Operation flowchart of control device 101 Operation flowchart of CPU 15 of arithmetic device 100 (first half) Operation flowchart of CPU 15 of arithmetic device 100 (second half) Examples of fringe images I _k1 , I _k2 , I _k3 , I _k4 Example of initial phase distribution φ _k (i) Example of phase distribution ψ _k (i) after unwrapping Example of height distribution Z _k (i) Example of height candidate Z _ki and evaluation value γ _ki Example of elected height Z _i Example of calculating the contrast value C _ki

[First Embodiment]
Hereinafter, a first embodiment of the present invention will be described. This embodiment is an embodiment of a three-dimensional shape measuring apparatus.

  FIG. 1 is a configuration diagram of the three-dimensional shape measuring apparatus of the present embodiment. As shown in FIG. 1, the three-dimensional shape measurement apparatus includes a stage 12 on which a measurement object 11 is placed, a projection unit 13, an imaging unit 14, a light source device 21, a control device 101, and a calculation device 100. Prepare. Among these, the projection unit 13, the imaging unit 14, and the light source device 21 are each connected to the control device 101, and are connected to the arithmetic device 100 via the control device 101.

  The projection unit 13 is arranged in such a posture that the optical axis is inclined with respect to the reference plane of the stage 12, and irradiates the measurement target 11 of the stage 12 with pattern light. The projection unit 13 includes an illumination element 22, a pattern formation unit 23, and a projection optical system 24.

  The light emitted from the light source device 21 is guided to the illumination element 22 of the projection unit 13 by the optical fiber 21 ′. The illumination element 22 converts the light into an illumination light beam in an appropriate state, and illuminates the pattern forming unit 23 with substantially uniform intensity.

  The pattern forming unit 23 is a panel (liquid crystal display element or the like) having a variable transmittance distribution, and gives a distribution to the cross-sectional intensity of the illumination light beam incident from the illumination element 22. The pattern forming unit 23 displays a striped pattern (sinusoidal lattice pattern) having a sinusoidal transmittance change in one direction, thereby making the cross-sectional intensity distribution of the illumination light beam sinusoidal.

  The illumination light beam emitted from the pattern forming unit 23 enters the measurement object 11 on the stage 12 through the projection optical system 24. As a result, a sinusoidal lattice pattern is projected onto the measurement object 11. In addition, since the sine lattice pattern projected on the measuring object 11 is deformed according to the surface shape of the measuring object 11, the surface shape of the measuring object 11 can be known from the deformation amount.

  The imaging unit 14 is disposed so that the optical axis is perpendicular to the reference surface of the stage 12, and an imaging optical system 25 that forms an image of reflected light from the measurement object 11 and an imaging optical system 25. And an image pickup device 26 for picking up an image of the measurement object 11 formed. The imaging optical system 25 is provided with a filter mechanism 25 ′ that is equipped with a plurality of filters having different characteristics and switches the filters inserted in the optical path between these filters. When the filter mechanism 25 ′ is driven, the state of light that can enter the image sensor 26 (for example, a combination of wavelength components and polarization states) changes.

  When the stage 12 is in the reference state, the optical axis of the projection unit 13 and the optical axis of the imaging unit 14 intersect at a certain position (reference position) on the reference plane of the stage 12, and these optical axes are The existing plane intersects the lattice line of the sine lattice pattern substantially perpendicularly, and the reference position on the pattern forming unit 23 and the reference position of the stage 12 are conjugate with respect to the projection optical system 24, and the reference of the stage 12 is present. The position and the reference position on the image sensor 26 are conjugate with respect to the imaging optical system 25.

  The control device 101 includes a CPU, a storage unit used during the operation of the CPU, and various drive circuits that operate under the control of the CPU. The storage unit stores an operation program for the CPU, and the operation of the CPU (that is, the operation of the control device 101) follows the operation program. Specifically, the control device 101 projects the sine lattice pattern onto the measurement object 11 by driving the light source device 21 and the pattern forming unit 23, and drives the imaging element 26 in this state to drive the measurement object 11. An image (stripe image) is acquired and sent to the arithmetic device 100.

  Note that the control device 101 can shift the phase of the sine lattice pattern projected onto the measurement object 11 by controlling the display pattern on the pattern forming unit 23. In addition, the control device 101 can change the focus position of the sine lattice pattern with respect to the measurement object 11 by displacing the stage 12 in the optical axis direction (Z direction) of the imaging unit 14. Further, the control device 101 can adjust the exposure amount of imaging by adjusting the charge accumulation time per frame of the imaging element 26. Further, the control device 101 can adjust the amount of projection light of the sine lattice pattern by adjusting the power of the light source device 21. Further, the control device 101 can adjust the state of light that can be detected by the image sensor 26 (for example, a combination of the wavelength component and the polarization state) by driving the filter mechanism 25 ′.

  Therefore, the control apparatus 101 can set various measurement conditions with different combinations of the following states (1) to (4) in the three-dimensional shape measurement apparatus.

  (1) The focus position of the sine lattice pattern.

  (2) Imaging exposure amount.

  (3) Projected light quantity of sine lattice pattern.

  (4) The state of light that can be detected.

Hereinafter, in the present embodiment, the settable measurement conditions in step S12 that the control unit 101 will be described _later, and _{k max} kinds of measurement conditions, between them _{k max} type of measurement condition states (2) to (4) Are common and states (1) are different from each other.

  The arithmetic device 100 includes a CPU 15, a storage unit 16, a monitor 17, and an input unit 18. The CPU 15 analyzes the fringe image sent from the control device 101 and acquires the surface shape data of the measurement object 11.

  The storage unit 16 is configured by a non-volatile storage medium such as a flash memory, and can store fringe image data sent from the control device 101 and surface shape data acquired by the CPU 15. The storage unit 16 stores an operation program for the CPU 15 in advance, and the operation of the CPU 15 follows the operation program.

  The monitor 17 displays the surface shape of the measurement object 11 according to the instruction from the CPU 15. The input unit 18 receives various instructions including a measurement start instruction from the user.

  FIG. 2 is an operation flowchart of the control apparatus 101. Hereinafter, each step will be described in order.

  Step S11: The control device 101 sets the condition number k to the initial value 1.

  Step S12: The control device 101 sets the measurement condition of the three-dimensional shape measurement apparatus as the kth measurement condition.

  Step S13: The control device 101 sets the image number m to the initial value 1.

  Step S14: The control device 101 sets the phase shift amount of the sine grating pattern to (m−1) π / 2.

Step S15: The control device 101 turns on the light source device 21 to project a sine lattice pattern having a phase shift amount of (m−1) π / 2 onto the measurement object 11, and in that state, the measurement object 11 The fringe image I _km is acquired, and the fringe image I _km is sent to the arithmetic device 100.

Step S16: The control apparatus 101 determines whether or not the current image number m has reached the maximum value m _max . If not, the control apparatus 101 proceeds to step S17, and if it has reached, the process proceeds to step S18.

Step S17: The control apparatus 101 increments the image number m, and then returns to step S14. In the present embodiment, it is assumed that the determination criterion (maximum value m _max ) in step S16 described above is set to 4. Therefore, the loop of steps S14 to S17 is repeated four times, and four striped images (stripe images I _{k1 to} I _k4 ) are acquired. In addition, _what is shown in FIG. 5 is an example of the fringe images I _{k1 to} I _k4 .

Step S18: The control device 101 determines whether or not the current condition number k has reached the maximum value k _max, and if not reached, proceeds to step S19, and if it has reached, ends the flow.

Step S19: The control device 101 increments the condition number k, and then returns to step S12. In the present embodiment, it is assumed that the discrimination criterion (maximum value k _max ) in step S18 described above is set to 3. Thus, the loop of steps S12~S19 are repeated three times, three types of four copies of the fringe image under measuring condition, i.e., 24 pieces of fringe images in total (fringe image _{I 11 ~I 14, I 21 ~I} 24 , I _{31 to} I ₃₄ ) are acquired.

FIG. 3 is an operation flowchart (first half) of the CPU 15 of the arithmetic device 100. Hereinafter, each step will be described in order. At the start of the flow, all the 24 striped images I _{11 to} I ₁₄ , I _{21 to} I ₂₄ , and I _{31 to} I ₃₄ acquired by the control device 101 are already stored in the storage unit 16 of the arithmetic device 100. is there.

  Step S21: The CPU 15 sets the condition number k to the initial value 1.

  Step S22: The CPU 15 sets the pixel number i to an initial value 1.

Step S23: The CPU 15 reads the four striped images I _{k1 to} I _k4 acquired under the k th measurement condition from the storage unit 16, and among the striped images I _{k1 to} I _k4 , four luminances related to the i th pixel. Reference is made to the values I _{k1i to} I _k4i . Then, the CPU 15 calculates the initial phase φ _ki by applying these four luminance values I _{k1i to} I _k4i to the equation (1) of the 4-bucket method as luminance change data during phase shift. Then, the CPU 15 stores the initial phase φ _ki in the storage unit 16 as the initial phase of the i-th pixel under the k-th measurement condition.

Step S24: The CPU 15 determines whether or not the current pixel number i has reached the maximum value i _max . If not, the process proceeds to step S25, and if it has reached, the process proceeds to step S26.

Step S25: The CPU 15 increments the pixel number i and then returns to step S23. The discrimination criterion (maximum value i _max ) in step S24 described above is set to be equivalent to the number of pixels of the image sensor 26 (the actual number of pixels is 40000 or more, but in the following, the number of pixels is set to 20 for simplicity. To do.) Therefore, the loop of steps S23 to S25 is repeated 20 times, and the distribution of the initial phase φ _ki (initial phase distribution φ _k (i)) is acquired. FIG. 6 shows an example of the initial phase distribution φ _k (i).

Step S26: The CPU 15 determines whether or not the current condition number k has reached the maximum value k _max (here, 3). If not, the process proceeds to step S27, and if it has reached, the process proceeds to step S28. .

Step S27: The CPU 15 increments the condition number k and then returns to step S22. Since the discrimination criterion (maximum value k _max ) in step S26 described above is 3, the loop of steps S22 to S27 is repeated three times, and the initial phase distribution for each of the three types of measurement conditions, that is, 3 in total. Two initial phase distributions (initial phase distributions φ ₁ (i), φ ₂ (i), φ ₃ (i)) are acquired.

  Step S28: The CPU 15 sets the condition number k to the initial value 1.

Step S29: CPU 15, the initial phase distribution of the k measurement condition phi _k (i) is read out from the storage unit 16, unwrapping (phase unwrapping by adding the offset distribution delta (i) in the initial phase distribution phi _k (i) ) To obtain the unwrapped phase distribution ψ _k (i) (Note that the offset distribution Δ (i) is separately measured and stored in the storage unit 16 in advance, or is automatically set by phase jump detection) ). FIG. 7 shows an example of the phase distribution ψ _k (i) after unwrapping. Furthermore, the CPU 15 converts the unwrapped phase distribution ψ _k (i) into a height distribution Z _k (i), and stores the height distribution Z _k (i) as a height distribution under the k-th measurement condition. Store in unit 16. FIG. 8 shows an example of the height distribution Z _k (i).

Step S30: The CPU 15 determines whether or not the current condition number k has reached the maximum value k _max (here, 3). If not, the process proceeds to step S31, and if it has reached, step S32 in FIG. Proceed to

Step S31: The CPU 15 increments the condition number k and then returns to step S29. Since the discrimination criterion (maximum value k _max ) in step S30 described above is 3, the loop of steps S29 to S31 is repeated three times, and the height distribution for each of the three types of measurement conditions, that is, 3 in total. Height distribution (height distribution Z ₁ (i) under the first measurement condition, height distribution Z ₂ (i) under the second measurement condition, height distribution Z ₃ (i) under the third measurement condition) Will be acquired.

Of the height distribution Z ₁ (i) under the first measurement condition, the height distribution Z ₂ (i) under the second measurement condition, and the height distribution Z ₃ (i) under the third measurement condition, The three heights Z _1i , Z _2i , and Z _3i related to the i pixel are used as height candidates related to the i-th pixel in the steps described later. Therefore, in the following, the three heights Z _1i , Z _2i , and Z _3i related to the i-th pixel are respectively expressed as “first height candidate Z _1i ”, “second height candidate Z _2i ”, and “third height candidate”. Z _3i ".

  FIG. 4 is an operation flowchart (second half) of the CPU 15 of the arithmetic device 100. Hereinafter, each step will be described in order.

  Step S32: The CPU 15 sets the condition number k to the initial value 1.

  Step S33: The CPU 15 sets the pixel number i to an initial value 1.

Step S34: The CPU 15 reads out the four striped images I _{k1 to} I _k4 acquired under the k th measurement condition from the storage unit 16, and among the striped images I _{k1 to} I _k4 , four luminance values related to the i th pixel. Referring to _{I k1i} ~I k4i, they luminance value _I k1i _{~I k4i} following equation (2) to calculate the evaluation value gamma _ki by fitting to the through (4). Then, the CPU 15 stores the evaluation value γ _ki in the storage unit 16 as the evaluation value of the k-th height candidate Z _ki of the i-th pixel. In the following description, it is _assumed that the evaluation value γ _ki is _assigned to the kth height candidate Z _ki .

Note that the evaluation value γ _ki calculated by the equations (2) to (4) is the luminance change data (here, the four luminance values I _{k1i to} I _k4i ) that is the calculation source of the k-th height candidate Z _ki . Contrast value. Therefore, the evaluation value gamma _ki, along with an evaluation value of the k-th height candidate _{Z ki,} luminance variation data that is the first k calculated original height candidate _{Z ki} (here four luminance values _I k1i _{~I k4i} ). As the evaluation value γ _ki is higher, the reliability of the luminance change data (here, the four luminance values I _{k1i to} I _k4i ) is higher, and the reliability of the kth height candidate Z _ki is also higher.

Step S35: The CPU 15 determines whether or not the current pixel number i has reached the maximum value i _max (here, 20). If not, the process proceeds to step S36, and if it has reached, the process proceeds to step S37. .

Step S36: The CPU 15 increments the pixel number i and then returns to step S34. Since the discrimination criterion (maximum value i _max ) in step S35 described above is set to 20, the loop of steps S34 to S36 is repeated 20 times to evaluate the evaluation value (evaluation value γ) for all pixel height candidates. _{k1 to} γ _k20 ). In addition, the left table of FIG. 9 is an example of evaluation values given to the first height candidates of all pixels. The “Z coordinate” in the table indicates the height candidate Z _ki , and the “γ value” indicates the evaluation value γ _ki of the height candidate Z _ki . The “X coordinate” and “Y coordinate” in the table are obtained by converting the position of each pixel into coordinates on the measurement object 11.

Step S37: The CPU 15 determines whether or not the current condition number k has reached the maximum value k _max . If not, the process proceeds to step S38, and if it has reached, the process proceeds to step S39.

Step S38: The CPU increments the condition number k and then returns to step S33. Since the discrimination criterion (maximum value k _max ) in step S37 described above is 3, the loop of steps S33 to S38 is repeated three times, and evaluation values (evaluation values γ _{11 to} γ ₁₂₀₎ for all height candidates of all pixels. , Γ _{21 to} γ ₂₂₀ , γ _{31 to} γ ₃₂₀ ). The left table in FIG. 9 is an example of evaluation values given to the first height candidates for all pixels, and the middle table in FIG. 9 shows the evaluation values given to the second height candidates for all pixels. FIG. 9 is an example, and the right table of FIG. 9 is an example of evaluation values given to the third height candidates of all pixels.

  Step S39: The CPU 15 sets the pixel number i to an initial value 1.

Step S40: The CPU 15 reads the first height candidate Z _1i , the second height candidate Z _2i , and the third height candidate Z _3i of the i-th pixel from the storage unit 16, and the first height candidate Z _1i , second Among the height candidates Z _2i and the third height candidates Z _3i , the one with the largest evaluation value is selected and stored in the storage unit 16 as the height Z _i of the i-th pixel.

Step S41: The CPU 15 determines whether or not the current pixel number i has reached the maximum value i _max . If not, the process proceeds to step S42, and if it has reached, the process proceeds to step S43.

Step S42: The CPU 15 increments the pixel number i and then returns to step S40. Since the discrimination criterion (maximum value i _max ) in step S41 described above is set to 20, the loop of steps S40 to S42 is repeated 20 times, and the heights of all pixels (heights Z _{1 to} Z ₂₀ ) are set. Will be elected.

  If the evaluation values of the first height candidate, the second height candidate, and the third height candidate of all the pixels are as shown in the left table, the middle table, and the right table of FIG. 9, respectively, The selected height is as shown in the table of FIG. In each table of FIG. 9, the height candidates given a circle are height candidates that have a larger evaluation value than the other two height candidates. The set of heights shown in the table of FIG. 10 matches the set of height candidates given a circle in each table of FIG.

Step S43: CPU 15, the set of height _Z 1 _{to Z 20} that is selected in the loop of steps S40～S42, i.e. height distribution Z a (i), the height distribution of the measurement object 11 Z (X, Y) And is stored in the storage unit 16 as surface shape data of the measurement object 11, and the flow ends. At this time, the CPU 15 may display the height distribution Z (X, Y) on the monitor 17.

As described above, the measurement apparatus of the present embodiment repeatedly acquires the luminance change data (here, the four luminance values I _{k1i to} I _k4i ) of each pixel while changing the focus position of the sine lattice pattern (steps S11 to S19). Among the plurality of luminance change data (luminance values I _{11i to} I _14i , luminance values I _{21i to} I _24i , luminance values I _{31i to} I _34i ) acquired for each pixel, derived from highly reliable luminance change data. The height candidate Z _ki is selected as the height Z _i of the pixel (steps S32 to S43).

  Therefore, according to the measurement apparatus of the present embodiment, it is possible to accurately measure a measurement object that is difficult to focus on the sine lattice pattern, such as a measurement object having a large surface height difference.

[Supplement to the embodiment]
In the above embodiment, as a method of changing the focus position of the sine lattice pattern, a method of displacing the stage 12 in the Z direction is adopted. However, other methods, for example, the projection unit 13 and the entire imaging unit 14 may be changed to Z. A method of displacing in the direction may be adopted.

  In the above embodiment, the contrast value γ of the luminance change data (here, four luminance values) from which the height candidate is calculated is used as the height candidate evaluation value. The amplitude value A of the luminance change data (here, four luminance values) may be used instead of the contrast value γ of four luminance values. The amplitude value A can be calculated by equation (2). A height candidate having a larger amplitude value A can be regarded as having higher reliability.

  In the above embodiment, the contrast value γ of the luminance change data (here, four luminance values) from which the height candidate is calculated is used as the height candidate evaluation value. The offset value B of the luminance change data (here, four luminance values) may be used instead of the contrast value γ of the four luminance values. The offset value B can be calculated by the equation (3). It can be considered that the height candidate with the smaller offset value B has higher reliability.

In the above embodiment, the contrast value γ of the luminance change data (here, four luminance values) that is the calculation source of the height candidate is used as the evaluation value of the height candidate. Instead of the contrast value γ, a contrast value C in the spatial direction may be used. Note that the contrast value C _{ki in the} spatial direction related to a certain pixel I _ki can be calculated by, for example, the following procedures (a) to (c) performed by the CPU 15.

(A) As shown by the arrows in FIG. 11, among the four striped images I _{k1 to} I _k4 , regions having sufficiently high luminance are connected to create one composite image I _k .

(B) A local area A _i centered on the pixel I _ki is set in the composite image I _k .

(C) calculating a difference between adjacent pixels in the local region A _i, the sum values in the local region A _i of the difference (or average value) calculated, the contrast value C _ki pixels I _ki that value And

  Moreover, in the said embodiment, although only one evaluation value was used for evaluation of a height candidate, you may use a some evaluation value. For example, both the contrast value γ and the contrast value C described above may be used. However, when a plurality of evaluation values are used, the reliability of the height candidate is determined based on the weighted average value of these evaluation values.

  Moreover, in the said embodiment, the procedure of the arithmetic unit 100 was made into the following (A)-(C).

  (A) A plurality of height candidates for all pixels are calculated from a plurality of luminance change data for all pixels (steps S21 to S31).

  (B) A highly reliable one is selected from a plurality of height candidates for each pixel (steps S32 to S42).

  (C) Surface shape data is created only with the height candidates selected for each pixel (step S43).

  However, the procedure of the arithmetic device 100 may be changed to the following (A ′) and (B ′).

  (A ′) Reliable luminance change data is selected for each pixel from a plurality of luminance change data for all pixels.

  (B ′) Surface shape data is created only from the luminance change data selected for each pixel.

  Incidentally, according to the procedures (A ′) and (B ′), the target of the phase calculation (calculation for calculating the phase from the luminance change data) can be limited to only necessary pixels, which is efficient.

  In the above embodiment, the measurement conditions that can be set in step S12 are the three measurement conditions different from each other in the state (1). However, the two measurement conditions different from each other in the state (1), or the state (1) It is good also as four or more different measurement conditions.

  In the above embodiment, the measurement conditions that can be set in step S12 are a plurality of measurement conditions that are different from each other only in the state (1). However, only one of the above-described states (2) to (4) is mutually connected. A plurality of different measurement conditions may be used.

  For example, when the measurement conditions that can be set in step S12 are a plurality of measurement conditions that are different from each other only in the state (2) or the state (3), even a measurement object with non-uniform surface reflectance can be accurately obtained. It can be measured well.

  For example, when the measurement conditions that can be set in step S12 are a plurality of measurement conditions that differ only in the state (4), even a measurement object with a non-uniform surface color or material can be measured with high accuracy. can do.

  In the above embodiment, the measurement conditions that can be set in step S12 are three measurement conditions that differ only in the state (1), but there are many different combinations of the states (2) to (4) described above. It is good also as measurement conditions.

  For example, when the measurement conditions that can be set in step S12 are various measurement conditions in which the combination of the state (1) and the state (2) is different from each other, the surface height difference is large and the reflectance is not uniform. Such a measurement object can be measured with high accuracy.

  In addition, for example, when the measurement conditions that can be set in step S12 are various measurement conditions in which the combination of the state (1) and the state (3) is different from each other, the surface height difference is large and the reflectance is high. A non-uniform measurement object can be measured with high accuracy.

  Further, for example, when the measurement conditions that can be set in step S12 are various measurement conditions in which the combination of the state (1) and the state (4) is different from each other, the difference in height of the surface is large, and the color or material However, it is possible to accurately measure a non-uniform measurement object.

  In the above-described embodiment, the arrangement of the filter mechanism 25 ′ is the projection optical system 24.

  In the above embodiment, the 4-bucket method in which the number of fringe images necessary for calculating the initial phase φ is 4, but the 3-bucket method in which the number is 3 and the number is 7 is used. Other phase shift methods, such as some 7-bucket methods, may be applied.

  Further, the program stored in the storage unit of the above embodiment may be a firmware program updated by version upgrade or the like. In other words, the measurement processing and analysis processing of this embodiment may be provided by updating the firmware program of the existing measurement processing and analysis processing.

  In the above embodiment, all of the measurement processing shown in FIG. 2 and the analysis processing shown in FIG. 3 and FIG. 4 are realized by software by the CPU. It may be realized in hardware by an ASIC.

  DESCRIPTION OF SYMBOLS 11 ... Measuring object, 12 ... Stage, 13 ... Projection part, 14 ... Imaging part 14, 21 ... Light source device, 101 ... Control apparatus, 100 ... Arithmetic unit

Claims (10)

Projecting means for projecting a fringe pattern onto the measurement object;
Imaging means for acquiring luminance change data from each position on the measurement object by repeating imaging of the measurement object while changing the phase of the fringe pattern projected on the measurement object;
Control means for acquiring a plurality of brightness change data from each position on the measurement object by repeatedly executing the acquisition of the brightness change data while changing the focus position of the stripe pattern with respect to the measurement object;
Selection means for selecting a highly reliable one from among a plurality of brightness change data acquired by the control means for each position on the measurement object;
Shape calculation means for obtaining the coordinates of each position represented by the luminance change data selected for each position on the measurement object as the surface shape of the measurement object;
A three-dimensional shape measuring apparatus comprising: The three-dimensional shape measuring apparatus according to claim 1,
The control means includes
The three-dimensional shape measuring apparatus, wherein the luminance change data is repeatedly acquired while changing the combination of the light state detectable by the imaging means and the focus position of the fringe pattern. The three-dimensional shape measuring apparatus according to claim 1,
The control means includes
The three-dimensional shape measuring apparatus, wherein the luminance change data is repeatedly acquired while changing a combination of a projected light amount of the fringe pattern or an exposure of the imaging unit and a focus position of the fringe pattern. In the three-dimensional shape measuring apparatus according to any one of claims 1 to 3,
The selection means is:
A three-dimensional shape measuring device characterized in that brightness change data with higher contrast is considered more reliable. In the three-dimensional shape measuring apparatus according to any one of claims 1 to 3,
The selection means is:
A three-dimensional shape measuring device characterized in that brightness change data with larger amplitude is considered to be more reliable. A projection procedure for projecting a fringe pattern onto the measurement object;
An imaging procedure for acquiring luminance change data from each position on the measurement object by repeating imaging of the measurement object while changing the phase of the fringe pattern projected on the measurement object;
A control procedure for acquiring a plurality of brightness change data from each position on the measurement object by repeatedly executing the acquisition of the brightness change data while changing the focus position of the stripe pattern with respect to the measurement object;
A selection procedure for selecting a highly reliable one from a plurality of brightness change data acquired in the control procedure, for each position on the measurement object,
A shape calculation procedure for obtaining the height of each position represented by the luminance change data selected for each position on the measurement object as a surface shape of the measurement object;
A three-dimensional shape measuring method comprising: In the three-dimensional shape measuring method according to claim 6,
In the control procedure,
The three-dimensional shape measurement method characterized by repeatedly acquiring the luminance change data while changing a combination of a light state detectable by the imaging procedure and a focus position of the stripe pattern. In the three-dimensional shape measuring method according to claim 6,
In the control procedure,
The three-dimensional shape measurement method, wherein the acquisition of the luminance change data is repeatedly executed while changing a combination of a projected light amount of the fringe pattern or an exposure of the imaging procedure and a focus position of the fringe pattern. In the three-dimensional shape measuring method according to any one of claims 6 to 8,
In the selection procedure,
A three-dimensional shape measurement method characterized in that brightness change data with higher contrast is considered more reliable. In the three-dimensional shape measuring apparatus as described in any one of Claims 6-8,
In the selection procedure,
A three-dimensional shape measurement method characterized in that brightness change data with larger amplitude is considered to be more reliable.

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