JP4398277B2 - 3D measuring device, 3D measuring method, and 3D measuring program - Google Patents

Description

  The present invention relates to a three-dimensional measurement technique, and more particularly to a three-dimensional measurement apparatus, a three-dimensional measurement method, and a three-dimensional measurement program for measuring the surface of a three-dimensional measurement object.

  There are a lattice pattern projection method and a lattice projection type moire method for measuring the three-dimensional shape of an object. The “lattice pattern projection method” refers to a method of projecting a lattice pattern and obtaining the height of each point on the surface of the object to be measured from the phase (see, for example, Non-Patent Document 1). In the grid pattern projection method, accuracy can be improved by reducing the pitch of the grid pattern.

On the other hand, the “grid projection type moire method” is a method in which a periodic lattice pattern projected onto an object to be measured is first imaged, and the obtained image is multiplied by a virtual lattice model in a computer to obtain a moire pattern. Is a method (see, for example, Non-Patent Document 2). Since the moire obtained at this time includes the spatial frequency component of the lattice and the spatial frequency component of the difference between the sum of the respective lattices and the spatial frequency component of the difference, the spatial frequency of the difference of each lattice using a spatial low-pass filter Extract only the ingredients. In the lattice projection type moire method, by adjusting the pitch of the lattice in the computer, the range of the spatial frequency component of the difference between the respective lattices can be narrowed, so that the phase jump can be reduced.
Toru Yoshizawa, “Lattice pattern projection type 3D measurement system”, 3D optics, Volume 1, Optical Technology Communications, 1993, p. 83-99 Junichi Kato and Ichiro Yamaguchi, “Real-time processing of fringe images using phase shift electronic moire”, Sensor Technology, Vol. 12, No. 7, 1992, p. 39-44

  However, the lattice pattern projection method has a problem that if the pitch of the lattice pattern is reduced, a large number of phase jumps occur in the height calculation results in proportion. Further, since many phase jumps occur, there is a problem that it takes time to connect the phases. On the other hand, in the lattice projection type moire method, since a spatial frequency filter is used, there is a problem that the spatial resolution is remarkably impaired and a fine shape cannot be measured.

  In view of the above problems, an object of the present invention is to provide a three-dimensional measurement apparatus, a three-dimensional measurement method, and a three-dimensional measurement program capable of significantly reducing phase jumps without impairing resolution.

In order to achieve the above object, the first feature of the present invention is that (a) a sinusoidal periodic bright / dark pattern having a first pitch is projected onto the object to be measured, and the phases of the objects to be measured are different. And (b) the same value as the vibration term that vibrates the light intensity of the pixels included in each of the plurality of captured images at the first frequency determined by the first pitch. It is assumed that there are multiple light intensity functions with different phases, including those with a phase difference of 180 degrees, including multiple sinusoidal functions that are expressed as the sum of the bias component terms that determine the center value of the vibration. And (c) generating a plurality of combinations of two light intensity functions whose phases are different from each other by 180 degrees from a plurality of light intensity functions , subtracting each of the combinations to remove a bias component term , A bar that calculates multiple basic functions And Ass erasing operation section, to each of the (d) a plurality of basis functions, a function of the sinusoidal different phases 90 degrees from each other, a plurality of memory grating functions which oscillates each at a second frequency determined by the second pitch The product of each is converted into a form expressed by the sum of the frequency component term of the difference between the first frequency and the second frequency and the frequency component term of the sum of the first frequency and the second frequency. and, a moire generation calculator for calculating a plurality of moire function to generate a plurality of combinations of the two moire functions the same absolute value of the term of the frequency components of the sum from each other from (e) a plurality of moire functions, the sum in this combination and removal by an operation cancel each other out to the section of the frequency components, from terms of the frequency components of the remaining difference by this calculation, three-dimensional measurement and a phase calculator for calculating the initial phase to reduce the number of phase unwrapping Is a device The gist of the door.

The second feature of the present invention is: (a) imaging that projects a sinusoidal periodic bright and dark pattern having a first pitch on a measured object and obtains a plurality of captured images having different phases of the measured object (B) The light intensity of the pixels included in each of the plurality of captured images has the same value as the vibration term that vibrates at the first frequency determined by the first pitch, and determines the center value of vibration. A light intensity extracting unit that assumes a plurality of sinusoidal functions each expressed by the sum of the bias component term and a plurality of light intensity functions that are different in phase, including those that are 180 degrees different from each other , (C) A memory grid memory that stores a first memory grid function group and a second memory grid function group that are sinusoidal functions that are 90 degrees out of phase with each other and that vibrate at a second frequency determined by the second pitch. Equipment and (d) multiple light intensity functions For each, the product obtained by multiplying each of the plurality of memory grating function included in each of the first memory grating function group and the second memory grating function group, the frequency component of the difference between the first frequency and the second frequency To a form represented by the sum of the term of the frequency component of the sum of the first frequency and the second frequency and the term of the second frequency component having the bias component as the amplitude, and a plurality of cosine functions and A positive cosine function calculation unit that calculates a plurality of sine functions, and (e) a second frequency component term that takes the sum of a plurality of cosine functions and uses the sum frequency component and bias component included in the plurality of cosine functions as amplitudes. The real part function is calculated by removing the sine function, the sum of multiple sine functions is added, and the frequency component of the sum included in the multiple sine functions and the second frequency component term whose amplitude is the bias component are removed. Real part calculation part that calculates function and (f) Imaginary part function with real part function The gist of the present invention is a three-dimensional measurement apparatus including an initial phase calculation unit that calculates an initial phase for reducing the number of phase unwrapping from the term of the frequency component of the difference by dividing and taking an arctangent.

The third feature of the present invention is that (a) a plurality of images in which a phase of the object to be measured is different is projected by projecting a sinusoidal periodic bright and dark pattern having a first pitch onto the object to be measured. (B) the light intensity extraction unit vibrates the light intensity of the pixels included in each of the plurality of captured images at a first frequency determined by the first pitch. A plurality of sinusoidal functions each represented by the sum of a vibration term and a bias component term that has the same value and determines the center value of vibration, including phases that are 180 degrees different from each other. Assuming multiple light intensity functions that are different from each other, the step of storing in the data storage device, and (c) the bias elimination operation unit generates a plurality of combinations of two light intensity functions whose phases are different from each other by 180 degrees. in and then, this combination Removing the section running respectively subtraction bias component, calculates a plurality of basic functions, and storing in the data storage device, respectively (d) moire generation operation unit of the plurality of basic functions, each other phase Is a sinusoidal function that differs by 90 degrees, and the product of each of a plurality of memory lattice functions that vibrate at the second frequency determined by the second pitch is the difference between the first frequency and the second frequency. Converting to a form represented by the sum of the frequency component term and the sum of the frequency component term of the first frequency and the second frequency, calculating a plurality of moire functions, and storing the data in a data storage device; (E) The phase calculation unit generates a plurality of combinations of two moire functions having the same absolute value of the sum frequency component terms from the plurality of moire functions, and cancels the sum frequency component terms from each other in this combination. Remove this operation And a step of calculating an initial phase for reducing the number of times of phase unwrapping from the term of the frequency component of the difference remaining by the above.

The fourth feature of the present invention is (a) a plurality of images in which a sine wave-like periodic bright and dark pattern having a first pitch is projected onto a measured object, and the captured image input unit has different phases of the measured object. (B) the light intensity extraction unit vibrates the light intensity of the pixels included in each of the plurality of captured images at a first frequency determined by the first pitch. A plurality of sinusoidal functions each represented by the sum of a vibration term and a bias component term that has the same value and determines the center value of vibration, including phases that are 180 degrees different from each other. Assuming a plurality of different light intensity functions and storing them in the data storage device, and (c) a sine wave function whose phase is 90 degrees different from each other for each of the plurality of light intensity functions. And decided on the second pitch The product of each of the plurality of memory lattice functions included in each of the first memory lattice function group and the second memory lattice function group that respectively vibrate at the second frequency is the first frequency and the second frequency. Convert to a format expressed by the sum of the difference frequency component term, the frequency component term of the sum of the first frequency and the second frequency, and the second frequency component term whose amplitude is the bias component, Calculating a cosine function and a plurality of sine functions, and storing them in a data storage device; and (d) a real part calculation unit taking a sum of a plurality of cosine functions and a plurality of sine functions to obtain a plurality of cosine functions. And calculating the real part function and the imaginary part function by removing the term of the second frequency component having the amplitude of the sum frequency component and the bias component included in the sine function, and storing them in the data storage device; (E) The initial phase calculation unit calculates the imaginary part function Divided in parts function by taking the arctangent, the term frequency component of the difference, is summarized in that a three-dimensional measurement method including the step of calculating the initial phase to reduce the number of phase unwrapping.

A fifth feature of the present invention is a three-dimensional measurement program for driving and controlling a three-dimensional measurement apparatus that measures the surface shape of the object to be measured. The three-dimensional measurement apparatus includes: projecting a sinusoidal periodic light-dark pattern having a pitch, and instructions for the phase of the measured object to obtain a different plurality of captured images, the light intensity of the pixels included in each of (b) a plurality of captured images A plurality of sinusoidal functions each represented by the sum of a vibration term that vibrates at a first frequency determined by the first pitch and a bias component term that has the same value and determines the center value of the vibration. And a command that assumes a plurality of light intensity functions with different phases, including those that are 180 degrees out of phase , and (c) a combination of two light intensity functions that are 180 degrees out of phase from each other. It generates a plurality, its in this combination Each performs subtraction to remove the section of the bias component, and instructions for calculating a plurality of basic functions, each of (d) a plurality of basis functions, a function of the sinusoidal phase are different from each other by 90 degrees, the second The product obtained by multiplying each of the plurality of memory lattice functions that vibrate at the second frequency determined by the pitch of the first frequency and the second frequency difference term, the first frequency and the second frequency An instruction for calculating a plurality of moire functions by converting the sum to the frequency component terms of the sum of frequencies and (e) absolute values of the sum frequency component terms from the plurality of moire functions are equal to each other. In order to reduce the number of phase unwrapping from the difference frequency component terms remaining by this calculation, by generating multiple combinations of two moire functions and removing the sum frequency component terms from each other in this combination. calculating the initial phase The gist is that it is a three-dimensional measurement program that executes a command to be executed.

A sixth aspect of the present invention is a three-dimensional measurement program for controlling driving the three-dimensional measurement apparatus for measuring the surface shape of the object to be measured, the three-dimensional measuring device, a first object to be measured (a) A command for projecting a periodic sinusoidal bright and dark pattern having a pitch and acquiring a plurality of captured images with different phases of the object to be measured; and (b) the light intensity of the pixels included in each of the plurality of captured images. A plurality of sinusoidal functions each represented by the sum of a vibration term that vibrates at a first frequency determined by the first pitch and a bias component term that has the same value and determines the center value of the vibration. There, the command phase assumed different light intensity function respectively include those different phases by 180 degrees to each other, (c) for each of the plurality of light intensity function, the phase is 90 degrees different from sinusoidal each other Function, at the second pitch A product obtained by multiplying each of a plurality of memory lattice functions included in each of the first memory lattice function group and the second memory lattice function group that respectively vibrate at a determined second frequency is obtained by multiplying the product of the first frequency and the second frequency by Convert to a format expressed by the sum of the difference frequency component term, the frequency component term of the sum of the first frequency and the second frequency, and the second frequency component term whose amplitude is the bias component, A command to calculate a cosine function and a plurality of sine functions, and (d) a sum of a plurality of cosine functions and a sum of a plurality of sine functions to obtain frequency components and biases of the sums included in the cosine functions and the sine functions. instructions for calculating the respective real part function and an imaginary part function component by removing the second term of the frequency component amplitude, divided by the real part function (e) the imaginary part function, by taking the arctangent From the difference frequency component term, the phase unwrap time And summarized in that a three-dimensional measurement program for executing instructions and calculating the initial phase to reduce.

  According to the present invention, it is possible to provide a three-dimensional measurement apparatus, a three-dimensional measurement method, and a three-dimensional measurement program capable of significantly reducing phase jumps without impairing resolution.

  Embodiments of the present invention will be described below. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, the drawings are schematic. Therefore, specific dimensions and the like should be determined in light of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

(First embodiment)
The moire three-dimensional shape measurement system according to the first embodiment of the present invention includes a central processing unit (CPU) 300, an imaging device 350, a memory grid storage device 332, an input device 340, and an output device 341 as shown in FIG. A program storage device 330 and a data storage device 331. Further, the CPU 300 includes an imaging device control unit 200, a captured image input unit 309, a light intensity extraction unit 310, a bias erasure calculation unit 311, a moire generation calculation unit 312, a phase calculation unit 313, a phase connection calculation unit 314, and an inclination correction calculation unit 315. And a height conversion operation unit 316.

  As shown in FIG. 2, the imaging device 350 includes a light source 10 that irradiates light to the measurement target object 5 to be measured, a first lens 11 that converts the light emitted from the light source 10 into parallel light, and parallel light. Is irradiated with the grating 3, the stage 80 on which the measured object 5 irradiated with the light transmitted through the grating 3 is mounted, the second lens 21 for collecting the reflected light from the measured object 5, and the reflected light A spatial filter 23 arranged near the focal point of light, an image sensor 20 that receives reflected light that has passed through the spatial filter 23, a stage drive unit 42 that moves the arrangement position of the stage 80, and a grating that moves the arrangement position of the grating 3 A drive unit 15 is provided.

Here, a linear light source such as a fluorescent discharge tube, a low-pressure mercury lamp, or a xenon lamp can be used as the light source 10. A cylindrical lens or the like can be used as the first lens 11, and a telecentric lens or the like can be used as the second lens 21. FIG. 3 (a) schematically shows the surface of the grating 3, and the surface of the grating 3 has a periodic transmittance distribution as shown in FIG. 3 (b). By irradiating light to the grating 3 from the light source 10, on the surface of the object to be measured 5, periodic light and dark pattern with a first pitch P _d is projected. The image sensor 20 can use a charge-coupled device (CCD) camera, etc., and the photoelectric conversion function of the CCD camera converts the brightness of the reflected light into the magnitude of the voltage, in the vertical (x) direction and the horizontal (y) direction. A digital image composed of a plurality of pixels arranged in a matrix is transmitted to the captured image input unit 309 shown in FIG.

  The imaging apparatus control unit 200 controls the stage driving unit 42 illustrated in FIG. 2 and the arrangement position of the stage 80 by supplying a control signal and the like to the imaging apparatus 350. Similarly, the grating driving unit 15 is controlled to move the arrangement position of the grating 3 in the periodic pattern direction of the grating 3. Further, the imaging device control unit 200 performs adjustment of the light intensity of the light source 10, control of the shutter speed of the image sensor 20, and the like.

A captured image input unit 309 illustrated in FIG. 1 irradiates the grating 3 illustrated in FIG. 2 arranged at a predetermined position with the light source 10, and the digital image of the measured object 5 captured by the image sensor 20 is a first image. It is defined as a captured image. Further, with respect to the first captured image and the grating 3 is moved by the grid driver 15 to move the quarter of the distance the light and dark pattern on the surface of the object to be measured 5 first pitch P _d imaging The obtained digital image is defined as a second captured image. Similarly, the light-dark pattern on the surface of the object to be measured 5, and the digital image are sequentially captured by moving a quarter of the length of the first pitch P _d third captured image, the fourth captured image Define each.

The light intensity extraction unit 310 illustrated in FIG. 1 includes a plurality of pixels arranged in a line in the x direction from each of the first to fourth captured images including a plurality of pixels arranged in the x direction and the y direction. Extract. Here, each pixel has light intensity data, and FIG. 4 shows an example of the light intensity distribution reproduced from the pixel extracted from the first captured image. It is assumed that the light intensity I ₁ (x) of the pixel at the coordinate x shown in FIG. 4 is expressed by the following equation (1). Similarly, FIG. 5 shows an example of the light intensity distribution reproduced from the second captured image, and the light intensity I ₂ (x) of the pixel at the coordinate x shown in FIG. 5 is expressed by the following equation (2). It is assumed. An example of the light intensity distribution reproduced from the third captured image is shown in FIG. 6, and the light intensity I ₃ (x) of the pixel shown in FIG. 6 is assumed to be expressed by the following equation (3). An example of the light intensity distribution reproduced from the fourth captured image is shown in FIG. 7, and it is assumed that the light intensity I ₃ (x) of the pixel shown in FIG. 7 is expressed by the following equation (4). :
I ₁ (x) = A × cos (2 πx / P _d + φ (x)) + B… (1)
I ₂ (x) = A × cos (2 πx / P _d + φ (x) + π / 2) + B… (2)
I ₃ (x) = A × cos (2 πx / P _d + φ (x) + π) + B… (3)
I ₄ (x) = A × cos (2 πx / P _d + φ (x) + 3 × π / 2) + B… (4)
Here, A and B are constants in each pixel, A is an amplitude, and B is a bias term. The value of A is determined by the reflectance of the optical system such as a lens and the surface of the object to be measured 5. The value of B is determined by factors such as stray light in addition to the reflectance of the optical system such as a lens and the surface of the object 5 to be measured. φ (x) indicates the phase.

1 subtracts the _third light intensity function I ₃ (x) from the first light intensity function I ₁ (x) calculated by the light intensity extraction section 310 and having phases different from each other by 180 degrees. The first basic function E ₁ (x) without the bias term B shown in FIG. 8 is calculated. Further, the second light intensity function I ₂ (x) is subtracted from the fourth light intensity function I ₄ (x) that is 180 degrees out of phase with each other, and the second basic function E ₂ without the bias term B shown in FIG. Calculate (x). Each of the first basic function E ₁ (x) and the second basic function E ₂ (x) is expressed by the following equations (5) and (6). :
E ₁ (x) = I ₁ (x)-I ₃ (x)
= 2A × cos (2πx / P _d + φ (x))… (5)
E ₂ (x) = I ₄ (x)-I ₂ (x)
= 2A × sin (2πx / P _d + φ (x))… (6)
The memory grid storage device 332 shown in FIG. 1 includes a first memory grid function G ₁ (x) and a second memory grid function G that are expressed by the following formulas (7) and (8) that are 90 degrees out of phase with each other. ₂ Save each of (x). :
G ₁ (x) = cos (2πx / P _m )… (7)
G ₂ (x) = sin (2πx / P _m )… (8)
Note that P _m is the second pitch set in the virtual lattice model stored in the memory lattice storage device 332 with respect to the first pitch P _d . The value of P _m can be input to an arbitrary value from the input device 340 shown in FIG. Note that the value of P _m uses the same system of units as P _d. For example, if the [mu] m is a unit of P _d, also units of P _m are set at [mu] m.

The moiré generation calculation unit 312 adds the first memory lattice function G ₁ (x) stored in the memory lattice storage device 332 to the first basic function E ₁ (x) calculated by the bias elimination calculation unit 311. The calculation shown in the following equation (9) and the calculation shown in the following equation (10) multiplied by the second memory lattice function G ₂ (x) are respectively performed, and the first moire function M ₁ (x ) And the second moire function M ₂ (x) shown in FIG. Further, the moire generation calculation unit 312 performs the calculation shown in the following equation (11) by multiplying the second basic function E ₂ (x) by the first memory lattice function G ₁ (x), and the second memory lattice function G _2. Each of the calculations shown in the following equation (12) multiplied by (x) is performed, and the third moire function M ₃ (x) shown in FIG. 12 and the fourth moire function M ₄ (x) shown in FIG. calculate. Further, the second term of each of the _{first to} fourth moire functions M ₁ (x) to M ₄ (x) is defined as a sum frequency component. :
M ₁ (x) = E ₁ (x) × G ₁ (x)
= 2A × cos (2πx / P _d + φ (x)) × cos (2πx / P _m )
= A × (cos (2πx (P _m -P _d ) / (P _m × P _d ) + φ (x)) + cos (2πx × (P _m + P _d ) / (P _m × P _d ) + φ (x))}… (9)
M ₂ (x) = E ₁ (x) × G ₂ (x)
= 2A × cos (2πx / P _d + φ (x)) × sin (2πx / P _m )
= A × (-sin (2πx (P _m -P _d ) / (P _m × P _d ) + φ (x)) + sin (2πx × (P _m + P _d ) / (P _m × P _d ) + φ (x))}… (10)
M ₃ (x) = E ₂ (x) × G ₁ (x)
= 2A × sin (2πx / P _d + φ (x)) × cos (2πx / P _m )
= A × (sin (2πx (P _m -P _d ) / (P _m × P _d ) + φ (x)) + sin (2πx × (P _m + P _d ) / (P _m × P _d ) + φ (x))}… (11)
M ₄ (x) = E ₂ (x) × G ₂ (x)
= 2A × sin (2πx / P _d + φ (x)) × sin (2πx / P _m )
= A × (cos (2πx (P _m -P _d ) / (P _m × P _d ) + φ (x))-cos (2πx × (P _m + P _d ) / (P _m × P _d ) + φ (x))}… (12)
The phase calculation unit 313 illustrated in FIG. 1 calculates the first moire function M ₁ (x) and the fourth moire function M ₄ (x ) To obtain the first difference frequency function L ₁ (x) shown in FIG. Further, the second moire function M ₂ (x) is subtracted from the _third moire function M ₃ (x) having the same sum frequency component, and the second difference frequency function L ₂ (x) shown in FIG. 15 is obtained. calculate. The frequency function L ₁ (x) of the first difference and the frequency function L ₂ (x) of the _second difference are expressed by the following expressions (13) and (14), respectively. :
L ₁ (x) = M ₁ (x) + M ₄ (x)
= 2 × A × cos (2πx (P _m -P _d ) / (P _m × P _d ) + φ (x)) (13)
L ₂ (x) = M ₃ (x)-M ₂ (x)
= 2 × A × sin (2πx (P _m -P _d ) / (P _m × P _d ) + φ (x)) (14)
Further, the phase calculation unit 313 divides the frequency function L ₂ (x) of the _second difference by the frequency function L ₁ (x) of the _first difference and takes the arc tangent thereof, thereby obtaining FIG. 16 and the following (15) The initial phase δ shown in the equation is calculated. :
δ = tan ^-1 (L ₂ (x) / L ₁ (x))
= 2 π × x / P _d -2 π × x / P _m + φ (x)… (15)
Since the initial phase δ is discontinuous in units of 2π as shown in FIG. 16, the phase connection calculation unit 314 shown in FIG. 1 phase-connects the initial phase δ by “phase unwrapping”. Phase unwrapping refers to connecting phases by adding or subtracting 2πn (n is an integer other than 0) so as to be continuous from surrounding phase data. The “phase unwrap start point” is where the phase calculation is first performed. Therefore, assuming that the measurement object 5 does not exist as a measurement start point, moire fringes do not exist, and phase unwrapping cannot be performed. By designating where the measured object 5 is present as the measurement start point, phase unwrapping without failure can be performed. By phase unwrapping, a connected phase function C (x) that is a continuous function is obtained as shown in FIG.

  The inclination correction calculation unit 315 shown in FIG. 1 approximates the post-connection phase function C (x) to a linear function by the least square method, and defines this as a correction expression V (x). Further, inclination correction is performed by subtracting the correction formula V (x) from the post-connection phase function C (x), and a post-correction phase function F (x) shown in FIG. 18 is calculated.

The height conversion calculation unit 316 shown in FIG. 1 converts the unit system of the corrected phase function F (x), and calculates the height function H (x) at the y-intercept of the measured object 5 shown in FIG. Here, if the angle between the direction perpendicular to the stage 80 in FIG. 2 and the traveling direction of the parallel light transmitted through the grating 3 is θ, the measurement range of the imaging device 350 is given by P _d / tan θ, which is Equivalent to 2π. Therefore, the unit system is converted by substituting the corrected phase function F (x) calculated by the inclination correction calculation unit 315 into the following equation (16), and the height H of the measured object 5 at the coordinate x ( x) is calculated. :
H (x) = (F (x) / 2π) × P _d / tanθ… (16)
Note that the data storage device 331 sequentially stores the calculation results by the CPU 300. The program storage device 330 stores an operating system that controls the CPU 300 and the like. As the data storage device 331 and the program storage device 330, for example, a recording medium for recording a program such as a semiconductor memory, a magnetic disk, an optical disk, a magneto-optical disk, and a magnetic tape can be used. As the input device 340, for example, a keyboard, a mouse, a voice device, or the like can be used. As the output device 341, a printer, a liquid crystal display (LCD), a CRT display, or the like can be used.

  Next, a three-dimensional measurement method according to the first embodiment of the present invention will be described with reference to the flowchart of FIG. Note that the calculation results by the CPU 300 shown in FIG. 1 are sequentially stored in the data storage device 331.

 (a) First, in step S90, the lattice 3 and the object to be measured 5 used for the three-dimensional measurement shown in FIG. 2 are prepared. The object to be measured 5 is placed on the stage 80. Next, in step S91, a control signal is sent from the imaging device control unit 200 shown in FIG. 1 to the stage drive unit 42 shown in FIG. 2, and the stage 80 is moved to a place where 3D measurement of the object 5 to be measured is suitably performed. Let Further, a control signal is sent from the imaging device control unit 200 to the light source 10 to adjust the light intensity of the light emitted from the light source 10. Proceeding to step S92, measurement conditions for performing three-dimensional measurement are set. The setting of the measurement condition refers to setting of the phase unwrapping method, setting of the phase unwrapping start point, setting of automatically detecting a place where the measured object 5 does not exist, and deleting the data at that place.

(b) In step S93, light is emitted from the light source 10 toward the first lens 11. The light incident on the first lens 11 becomes parallel light and enters the grating 3. Collimated light transmitted through the grating 3 forms a sinusoidal periodic light-dark pattern having a first pitch P _d to the object to be measured 5 surface. Here, a control signal is sent from the imaging device control unit 200 to the image sensor 20, and the image sensor 20 opens the shutter and captures a surface image of the measured object 5 on which a light and dark pattern is formed. Next, the control signals to the grid driver 15 is transmitted from the imaging apparatus control unit 200, by moving the grating 3, sinusoidal periodic brightness having a first pitch P _d of the surface of the object to be measured 5 the pattern is moved a quarter of the length of the first pitch P _d in the same direction as the first pitch P _d, imaging the surface image of the object to be measured 5. Further, the movement and imaging of the lattice 3 are repeated to obtain a total of four captured images.

(c) The acquired four captured images are sequentially captured in the captured image input unit 309 shown in FIG. 1 in step S95, and the first captured image, the second captured image, the third captured image, It is defined as 4 captured images. Next, in step S100, the light intensity extraction unit 310 extracts the light intensity from each of the first to fourth captured images, and each of the extracted light intensities is the first light intensity shown in the above equation (1). Function I ₁ (x), second light intensity function I ₂ (x) shown in equation (2) above, third light intensity function I ₃ (x) shown in equation (3) above, (4 ) It is assumed that each of the fourth light intensity functions I ₄ (x) shown in the equation is expressed.

(d) In step S101, the bias erasure calculation unit 311 subtracts the _third light intensity function I ₃ (x) from the _first light intensity function I ₁ (x), and the bias term shown in the above equation (5) Get the first basic function E ₁ (x) without B. In addition, the bias erasure calculation unit 311 subtracts the _second light intensity function I ₂ (x) from the _fourth light intensity function I ₄ (x), so that the second without the bias term B shown in the above equation (6) is obtained. To obtain the basic function E ₂ (x).

(e) In step S102, the value of the second pitch P _m stored in the memory grid storage device 332 from the input device 340 is related to P _m > P _d / 2 with respect to the first pitch P _d . Set to a value that satisfies. The reason why the relationship between P _m and P _d is set in this way will be described later. Next, the moire generation calculation unit 312 stores the first memory lattice function G ₁ (x) shown in the above equation (7) stored in the memory lattice storage device 332 and the second memory shown in the above equation (8). Read the memory grid function G ₂ (x). Further, the moire generation calculation unit 312 calculates the first basic function E ₁ (x) by the first memory lattice function G ₁ (x) and the second memory lattice function G ₂ (x). Then, the first moire function M ₁ (x) shown in the equation (9) and the second moire function M ₂ (x) shown in the equation (10) are calculated. Similarly, the calculation of multiplying the second basic function E ₂ (x) by the first memory lattice function G ₁ (x) and the calculation of multiplying the second memory lattice function G ₂ (x) are performed, respectively. Each of the third moire function M ₃ (x) shown in equation (11) and the fourth moire function M ₄ (x) shown in equation (12) is calculated.

(f) In step S103, the phase calculation unit 313 calculates the sum of the first moire function M ₁ (x) and the fourth moire function M ₄ (x), and the first difference expressed by the above equation (13). The frequency function L ₁ (x) of is calculated. Further, the phase calculating unit 313 subtracts the _second moire function M ₂ (x) from the _third moire function M ₃ (x), and the second difference frequency function L ₂ (x ) Is calculated. Further, the phase calculation unit 313 divides the frequency function L ₂ (x) of the _second difference by the frequency function L ₁ (x) of the _first difference, and takes the arc tangent to obtain the initial phase shown in the above equation (15). δ is calculated.

 (g) Next, in step S104, the phase connection calculation unit 314 calculates a post-connection phase function C (x) by performing phase unwrapping on the initial phase δ. In step S105, the inclination correction calculation unit 315 approximates the post-connection phase function C (x) to a linear function of x by the least square method, and defines this as a correction expression V (x). Further, the inclination correction calculation unit 315 corrects the inclination by subtracting the correction equation V (x) from the post-connection phase function C (x), and calculates the post-correction phase function F (x). In step S106, the height conversion calculation unit 316 calculates the height H (x) at the coordinate x of the measured object 5 shown in FIG. 1 from the corrected phase function F (x) by the above equation (16).

According to the three-dimensional measurement apparatus and the three-dimensional measurement method according to the first embodiment of the present invention described above, it is possible to significantly reduce the phase jump in step S103 in FIG. In the conventional grid pattern projection method, after calculating the first to fourth light intensity functions I ₁ (x) to I ₄ (x) shown in the above equations (1) to (4), the following ( The phase δ _E was calculated by the equation (17) and the phase was unwrapped. :
δ _E = tan ^-1 ((I ₄ (x)-I ₂ (x)) / (I ₁ (x)-I ₃ (x)))
= 2 π × x / P _d + φ (x)… (17)
On the other hand, the initial phase δ shown in the above equation (15) according to the first embodiment effectively suppresses the phase jump because the second term (−2π × x / P _m ) exists. It becomes possible to do. Here, the reason for setting the second pitch P _m of the virtual memory lattice to satisfy the relationship of P _m > P _d / 2 with respect to the first pitch P _d in the description of step S102 in FIG. As shown in the following equation (18), the absolute value of the sum of the first term (2 π × x / P _d ) and the second term (−2 π × x / P _m ) in equation (15) is expressed as (17 This is because, by making it smaller than the first term (2π × x / P _d ) of the formula (1), it is possible to effectively suppress the phase jump as compared with the conventional grating pattern projection method. Therefore, the relationship of P _m > P _d / 2 is derived from the following equation (18). :
| 2 π × x / P _d -2 π × x / P _m | <2 π × x / P _d … (18)
In particular by setting the second pitch P _m of the virtual grid model equal to the first pitch P _d, the sum of the (15) first and second terms of zero. Therefore, the initial phase shown in the equation (15) is represented by δ = φ (x). Therefore, the phase skip does not occur, and the phase unwrapping in step S104 shown in FIG. 20 becomes unnecessary. Conventionally, a large amount of calculation time was required for phase unwrapping, but according to the first embodiment of the present invention, calculation required from imaging of the measured object 5 to calculation of the height function H (x) The time can be greatly reduced.

  Furthermore, the three-dimensional measurement apparatus and the three-dimensional measurement method according to the first embodiment do not use a spatial frequency filter unlike the conventional grating projection type moire method, so that the resolution does not decrease. As described above, according to the three-dimensional measurement apparatus and the three-dimensional measurement method according to the first embodiment, high-speed three-dimensional shape measurement can be performed without causing a reduction in resolution.

  Further, the above-described three-dimensional measurement method can be expressed as a series of processes or operations connected in time series. Therefore, in order to execute the three-dimensional measurement method in the computer system, the three-dimensional measurement method shown in FIG. 20 can be realized by a computer program product that specifies a plurality of functions performed by a processor or the like in the computer system. Here, the computer program product refers to a recording device or a recording medium that can be inputted to and outputted from a computer system such as the program storage device 330 shown in FIG. The recording medium includes a memory device, a magnetic disk device, an optical disk device, and other devices capable of recording other programs.

(Second embodiment)
The moire three-dimensional shape measurement system according to the second embodiment of the present invention shown in FIG. 21 is different from FIG. 1 in that the central processing unit (CPU) 400 has a positive cosine function calculation unit 412, a real part calculation unit 411, and The initial phase calculation unit 413 is provided, and the memory grid storage device 432 is connected to the CPU 400.

  The imaging device 350, the imaging device control unit 200, the captured image input unit 309, and the light intensity extraction unit 310 are the same as those in the moiré three-dimensional shape measurement system shown in FIG.

The memory grid storage device 432 shown in FIG. 21 is expressed by the following formulas (19) to (23), and the memory grid functions S ₁ (x), S ₂ (x), S ₃ ( Save x), S ₄ (x), S ₅ (x). :
S ₁ (x) = cos (2πx / P _m )… (19)
S ₂ (x) = cos (2πx / P _m + π / 2) = -sin (2πx / P _m )… (20)
S ₃ (x) = cos (2πx / P _m + π) = -cos (2πx / P _m )… (21)
S ₄ (x) = cos (2πx / P _m + 3π / 2) = sin (2πx / P _m )… (22)
S ₅ (x) = cos (2πx / P _m + 2π) = cos (2πx / P _m )… (23)
Here, the set of memory lattice functions S ₁ (x), S ₂ (x), S ₃ (x), and S ₄ (x) is defined as the first memory lattice function group, and the first memory lattice function memory grating function S ₁ included in the group _{(x), S 2 (x} ), S 3 (x), S 4 memory grating function phase is different by 90 degrees with respect to each of _{(x) S 2 (x)} , S _A set consisting of ₃ (x), S ₄ (x), and S ₅ (x) is defined as a second memory lattice function group.

The cosine function calculation unit 412 stores the memory lattice function S ₁ (x) of the first memory lattice function group in the memory lattice with respect to the first light intensity function I ₁ (x) calculated by the light intensity extraction unit 310. By performing reading and multiplication from the device 432, the calculation shown in the following equation (24) is performed to calculate the first cosine function N ₁ (x). Further, the second cosine function N 2 is calculated by multiplying the second light intensity function I ₂ (x) by the memory lattice function S ₂ (x) of the first memory lattice function group as shown in the following equation (25). ₂ Calculate (x). Similarly, the third light intensity function I ₃ (x) is multiplied by the memory lattice function S ₃ (x) of the first memory lattice function group, the calculation shown in the following equation (26), and the fourth light intensity function Multiplying I ₄ (x) by the memory lattice function S ₄ (x) of the first memory lattice function group, the calculation shown in the following equation (27) is performed, and the third cosine function N ₃ (x) and the fourth cosine function N ₃ (x) Each cosine function N ₄ (x) is calculated. :
N ₁ (x) = I ₁ (x) × S ₁ (x)
= {A × cos (2πx / P _d + φ (x)) + B} × cos (2πx / P _m )
= A / 2 × (cos (2πx × (P _m -P _d ) / (P _m × P _d ) + φ (x)) + cos (2πx × (P _m + P _d ) / (P _m × P _d ) + φ (x))} + B × cos (2πx / P _m )… (24)
N ₂ (x) = I ₂ (x) × S ₂ (x)
= {A × cos (2πx / P _d + φ (x) + π / 2) + B} × {-sin (2πx / P _m )}
= A × sin (2πx / P _d + φ (x)) × sin (2πx / P _m )-B × sin (2πx / P _m )
= A / 2 × (cos (2πx × (P _m -P _d ) / (P _m × P _d ) + φ (x))-cos (2πx × (P _m + P _d ) / (P _m × P _d ) + φ (x))}-B × sin (2πx / P _m )… (25)
N ₃ (x) = I ₃ (x) × S ₃ (x)
= {A × cos (2 πx / P _d + φ (x) + π) + B} × {-cos (2πx / P _m )}
= {A × cos (2 πx / P _d + φ (x))-B} × cos (2πx / P _m )
= A / 2 × (cos (2πx × (P _m -P _d ) / (P _m × P _d ) + φ (x)) + cos (2πx × (P _m + P _d ) / (P _m × P _d ) + φ (x))}-B × cos (2πx / P _m )… (26)
N ₄ (x) = I ₄ (x) × S ₄ (x)
= {A × cos (2 πx / P _d + φ (x) + 3 × π / 2) + B} × sin (2πx / P _m )
= {A × sin (2 πx / P _d + φ (x)) + B} × sin (2πx / P _m )
= A / 2 × (cos (2πx × (P _m -P _d ) / (P _m × P _d ) + φ (x))-cos (2πx × (P _m + P _d ) / (P _m × P _d ) + φ (x))} + B × sin (2πx / P _m )… (27)
As described above, the positive cosine function calculation unit 412 has a memory lattice function S ₁ having a phase of φ (x) different from each of the first to fourth light intensity functions I ₁ (x) to I ₄ (x). Each of the first to fourth cosine functions N ₁ (x) to N ₄ (x) is calculated by multiplying each of (x) to S ₄ (x).

Further, the positive cosine function calculation unit 412 reads and multiplies the memory lattice function S ₂ (x) of the second memory lattice function group from the memory lattice storage device 432 with respect to the _first light intensity function I ₁ (x), The calculation shown in the following equation (28) is performed to calculate the first sine function O ₁ (x). Further, the second light intensity function I ₂ (x) is multiplied by the memory lattice function S ₃ (x) of the second memory lattice function group to perform the calculation shown in the following equation (29), and the second sine function O ₂ Calculate (x). Similarly, the third light intensity function I ₃ (x) is multiplied by the memory lattice function S ₄ (x) of the second memory lattice function group, the calculation shown in the following equation (30), and the fourth light intensity function Multiplying I ₄ (x) by the memory lattice function S ₅ (x) of the second memory lattice function group, the calculation shown in the following equation (31) is performed, and the third sine function O ₃ (x) and the fourth Each of the sine functions O ₄ (x) is calculated. :
O ₁ (x) = I ₁ (x) × S ₂ (x)
= {A × cos (2πx / P _d + φ (x)) + B} × {-sin (2πx / P _m )}
= A / 2 × (sin (2πx × (P _m -P _d ) / (P _m × P _d ) + φ (x))-sin (2πx × (P _m + P _d ) / (P _m × P _d ) + φ (x))}-B × sin (2πx / P _m )… (28)
O ₂ (x) = I ₂ (x) × S ₃ (x)
= {A × cos (2πx / P _d + φ (x) + π / 2) + B} × {-cos (2πx / P _m )}
= (A × sin (2πx / P _d + φ (x))-B} × cos (2πx / P _m )
= A / 2 × (sin (2πx × (P _m -P _d ) / (P _m × P _d ) + φ (x)) + sin (2πx × (P _m + P _d ) / (P _m × P _d ) + φ (x))}-B × cos (2πx / P _m )… (29)
O ₃ (x) = I ₃ (x) × S ₄ (x)
= (A × cos (2 πx / P _d + φ (x) + π) + B} × sin (2πx / P _m )
= {-A × cos (2 πx / P _d + φ (x)) + B} × sin (2πx / P _m )
= A / 2 × (sin (2πx × (P _m -P _d ) / (P _m × P _d ) + φ (x))-sin (2πx × (P _m + P _d ) / (P _m × P _d ) + φ (x))} + B × sin (2πx / P _m )… (30)
O ₄ (x) = I ₄ (x) × S ₅ (x)
= {A × cos (2 πx / P _d + φ (x) + 3 × π / 2) + B} × cos (2πx / P _m )
= {A × sin (2 πx / P _d + φ (x)) + B} × cos (2πx / P _m )
= A / 2 × (sin (2πx × (P _m -P _d ) / (P _m × P _d ) + φ (x)) + sin (2πx × (P _m + P _d ) / (P _m × P _d ) + φ (x))} + B × cos (2πx / P _m )… (31)
As described above, the positive cosine function calculation unit 412 has a phase of (π / 2 − φ (x)) for each of the first to fourth light intensity functions I ₁ (x) to I ₄ (x). Each of the first to fourth sine functions O ₁ (x) to O ₄ (x) is calculated by multiplying the different memory lattice functions S ₂ (x) to S ₅ (x).

The real part calculation unit 411 performs the calculation shown in the following equation (32) that takes the sum of the _{first to} fourth cosine functions N ₁ (x) to N ₄ (x) calculated by the positive cosine function calculation unit 412. The real function R (x) is calculated, and the bias component B is removed. :
R (x) = N ₁ (x) + N ₂ (x) + N ₃ (x) + N ₄ (x)
= 2 × A × cos (2πx × (P _m -P _d ) / (P _m × P _d ) + φ (x))… (32)
Further, the real part calculation unit 411 performs the calculation shown in the following equation (33) that takes the sum of the _{first to} fourth sine functions O ₁ (x) to O ₄ (x) calculated by the cosine function calculation unit 412. Then, the imaginary part function J (x) is calculated, and the bias component B is removed. :
J (x) = O ₁ (x) + O ₂ (x) + O ₃ (x) + O ₄ (x)
= 2 × A × sin (2πx × (P _m -P _d ) / (P _m × P _d ) + φ (x))… (33)
The initial phase calculation unit 413 divides the imaginary part function J (x) calculated by the real part calculation unit 411 by the real part function R (x), and takes its arc tangent to obtain the initial value shown in the following equation (34). The phase δ is calculated. :
δ = tan ^-1 (J (x) / R (x))
= 2 π × x / P _d -2 π × x / P _m + φ (x)… (34)
The phase connection calculation unit 314 performs phase connection of the initial phase δ calculated by the initial phase calculation unit 413 by phase unwrapping as in FIG. Further, since the inclination correction calculation unit 315, the height conversion calculation unit 316, the input device 340, the output device 341, the program storage device 330, and the data storage device 331 are the same as those in FIG.

  Next, a three-dimensional measurement method according to the second embodiment of the present invention will be described with reference to the flowchart of FIG. Note that the calculation results by the CPU 400 shown in FIG. 21 are sequentially stored in the data storage device 331.

(a) Steps S90 to S100 are the same as those in the three-dimensional measurement method according to the first embodiment shown in FIG. In step S201, the positive cosine function calculation unit 412 extracts the first to fourth light intensity functions I ₁ (x) to I ₄ (x) shown in the above expressions (1) to (4) extracted by the light intensity extraction unit 310. Are read from the memory grid storage device 432, respectively, in the memory grid functions S ₁ (x) to S ₄ (x) of the first memory grid function group shown in the equations (19) to (22). Further, the cosine function calculation unit 412 multiplies each of the first to fourth light intensity functions I ₁ (x) to I ₄ (x) by each of the memory lattice functions S ₁ (x) to S ₄ (x), First to fourth cosine functions N ₁ (x) to N ₄ (x) shown in the above equations (24) to (27) are calculated.

(b) In step S202, the cosine function calculation unit 412 shows the above-described equations (20) to (23) for each of the first to fourth light intensity functions I ₁ (x) to I ₄ (x). Then, each of the memory lattice functions S ₂ (x) to S ₅ (x) of the second memory lattice function group is read from the memory lattice storage device 432. Further, the cosine function calculation unit 412 multiplies each of the first to fourth light intensity functions I ₁ (x) to I ₄ (x) by each of the memory lattice functions S ₂ (x) to S ₅ (x), First to fourth sine functions O ₁ (x) to O ₄ (x) shown in the expressions (28) to (31) are calculated.

(c) In step S203, the real part calculation unit 411 calculates the sum of the _{first to} fourth cosine functions N ₁ (x) to N ₄ (x) calculated by the positive cosine function calculation unit 412 in step S201 (32 ), The real function R (x) is calculated, and the bias component B is removed. Further, in step S204, the real part calculation unit 411 takes the sum of the _{first to} fourth sine functions O ₁ (x) to O ₄ (x) calculated by the cosine function calculation unit 412 in step S202. The imaginary part function J (x) is calculated and the bias component B is removed.

 (d) In step S205, the initial phase calculation unit 413 divides the imaginary part function J (x) calculated in step S204 by the real part function R (x) calculated in step S203, and takes its arc tangent. The initial phase δ shown in the above equation (34) is calculated. Hereinafter, steps S104 to S106 are the same as those in FIG.

Also in the three-dimensional measurement apparatus and the three-dimensional measurement method according to the second embodiment of the present invention described above, the initial phase δ calculated in step S205 in FIG. 22 is the second value as shown in the above equation (34). The term (−2π × x / P _m ) is provided, and the phase jump can be effectively suppressed as in the first embodiment. The (18) as described in equation with respect to the first pitch P _d at step S201 and step S202, the virtual second pitch P _m of the memory lattices of P _m> P _d / 2 related By setting so as to satisfy, it is possible to effectively suppress the phase jump compared to the conventional grating pattern projection method. Furthermore, if the second pitch P _m of the virtual lattice model is set to a value equal to the first pitch P _d , the initial phase shown in the above equation (34) is expressed by δ = φ (x), and the phase Skipping does not occur, and the phase unwrapping in step S104 shown in FIG. 22 becomes unnecessary.

  As a specific example, a mirror is arranged as the object to be measured 5 on the stage 80 shown in FIG. 2 in step S90 in FIG. 22, and the first to second images shown in FIG. FIG. 24 shows a mirror surface shape image reproduced in step S106 by the fourth captured image, which is reproduced by the three-dimensional measurement system and method according to the second embodiment. In the mirror surface shape image reproduced by the conventional phase shift method shown in FIG. 25, a phase jump occurs due to the spatial frequency component of the grating. On the other hand, no phase jump occurs in the mirror surface shape image calculated by the three-dimensional measurement system and method according to the second embodiment shown in FIG. Therefore, it becomes possible to accurately evaluate the surface shape of the mirror.

  Also in the 3D measurement method according to the second embodiment described above, the 3D measurement method shown in FIG. 22 can be realized by a computer program product that specifies a plurality of functions performed by a processor in the computer system. This is the same as in the first embodiment.

(Modification of the second embodiment)
In the second embodiment, the positive cosine function calculation unit 412 illustrated in FIG. 21 has a memory lattice function S ₂ for each of the first to fourth light intensity functions I ₁ (x) to I ₄ (x). Each of the first to fourth sine functions O ₁ (x) to O ₄ (x) is calculated by multiplying each of (x) to S ₅ (x). On the other hand, the memory lattice function S ₁ (x) is multiplied by the _second light intensity function I ₂ (x), and the memory lattice function S ₂ (x) is similarly applied to the third light intensity function I ₃ (x ), The memory lattice function S ₃ (x) is multiplied by the fourth light intensity function I ₄ (x), and the memory lattice function S ₄ (x) is multiplied by the first light intensity function I ₁ (x). It is possible to calculate a sine function similar to each of the _{first to} fourth sine functions O ₁ (x) to O ₄ (x).

Further, in the description of the memory grid storage device 432 shown in FIG. 21, it has been described that the memory grid functions S ₁ (x) to S ₅ (x) represented by the formulas (19) to (23) are stored, but the formula (21) The memory lattice function S ₃ (x) is the same as the memory lattice function S ₁ (x) in the equation (19) except for the sign. Further, the memory lattice function S ₄ (x) in the equation (22) is the same as the memory lattice function S ₂ (x) in the equation (20) except for the sign. Furthermore, the memory lattice function S ₅ (x) in the equation (23) and the memory lattice function S ₁ (x) in the equation (19) that are 180 degrees out of phase with each other are substantially the same. Therefore, the memory grid storage device 432 may store only the memory grid function S ₁ (x) of the formula (19) and the memory grid function S ₂ (x) of the formula (20).

In this case, the positive cosine function calculation unit 412 calculates the third cosine function N ₃ (x) and the fourth cosine function N ₄ (x) according to the following expressions (35) and (36), respectively, Each of the second sine function O ₂ (x) and the third sine function O ₃ (x) may be calculated from the expressions (37) and (38).

N ₃ (x) = I ₃ (x) × (-S ₁ (x))… (35)
N ₄ (x) = I ₄ (x) × (-S ₂ (x))… (36)
O ₂ (x) = I ₂ (x) × (-S ₁ (x))… (37)
O ₃ (x) = I ₃ (x) × (-S ₂ (x))… (38)
Furthermore, it is needless to say that the three-dimensional measurement method according to the second embodiment is not limited to the order shown in FIG. For example, after step S100, the process proceeds to step S202 to calculate the _{first to} fourth sine functions O ₁ (x) to O ₄ (x), and after calculating the imaginary part function J (x) in step S204, step S201 is performed. Step S203 and Step S205 may be proceeded to.

(Other embodiments)
As described above, the present invention has been described according to the embodiment. However, it should not be understood that the description and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques should be apparent to those skilled in the art. For example, in the first embodiment, a method of irradiating the grating 3 with the light source 10 is shown as a method of projecting a sinusoidal periodic bright and dark pattern having the first pitch on the measured object 5. Divide the light emitted from the light source into two luminous fluxes and overlap them on the surface of the object to be measured 5 again to form interference fringes on the object to be measured 5, or divide the light from the light source into two luminous fluxes and measure one of them. The first embodiment can also be applied to a method of irradiating the object 5 and overlapping the other with an image sensor such as a CCD camera to form interference fringes. In the first embodiment, the light that passes through the grating 3 and irradiates the object 5 to be measured is converted into parallel light by the first lens 11, and the parallel light component of the reflected light is converted into the first light as shown in FIG. Although the light is focused on the image sensor 20 by the lens 21 of 2, the light irradiating the object to be measured 5 is not limited to parallel light, and the present invention is applied to a system in which the first lens 11 and the second lens 21 are omitted. Applicable. Furthermore, by sequentially moving a quarter of the length of the first pitch P _d, from the first to get the fourth captured image, the light intensity extraction unit 310 shown in FIG. 1 (1) to ( 4) The formula was calculated. However, as long as the above formulas (5) and (6) can be obtained, the bias erasure calculation unit performs a calculation to take a plurality of captured images that are 180 degrees out of phase with the imaging device 350 and remove the bias term. 311 may be performed, and the present invention is not limited to the embodiment. For example, n as 0 or a natural number, is sequentially moved a distance of the first pitch P _d (1/4 + n), it may be the first to get the fourth captured image. Thus, it should be understood that the present invention includes various embodiments and the like not described herein. Therefore, the present invention is limited only by the invention specifying matters in the scope of claims reasonable from this disclosure.

1 is a block diagram of a three-dimensional measurement apparatus according to a first embodiment of the present invention. 1 is a schematic diagram of an imaging apparatus according to a first embodiment of the present invention. FIG. 3 is a schematic diagram of a lattice according to the first embodiment of the present invention. 3 is a graph of a light intensity function (part 1) according to the first embodiment of the present invention. 3 is a graph of a light intensity function (part 2) according to the first embodiment of the present invention. 6 is a graph of a light intensity function (part 3) according to the first embodiment of the present invention. 6 is a graph of a light intensity function (part 4) according to the first embodiment of the present invention. 3 is a graph of a basic function (part 1) according to the first embodiment of the present invention. 4 is a graph of a basic function (part 2) according to the first embodiment of the present invention. 5 is a graph of a moire function (part 1) according to the first embodiment of the present invention. 3 is a graph of a moire function (part 2) according to the first embodiment of the present invention. 4 is a graph of a moire function (part 3) according to the first embodiment of the present invention. 6 is a graph of a moire function (part 4) according to the first embodiment of the present invention. 4 is a graph of a difference frequency function (part 1) according to the first embodiment of the present invention. 4 is a graph of a difference frequency function (part 2) according to the first embodiment of the present invention. 4 is a phase graph according to the first embodiment of the present invention. 3 is a graph of a post-connection phase function according to the first embodiment of the present invention. 5 is a graph of a corrected phase function according to the first embodiment of the present invention. 3 is a graph of a height function according to the first embodiment of the present invention. 3 is a flowchart showing a measurement method according to the first embodiment of the present invention. FIG. 4 is a block diagram of a three-dimensional measuring apparatus according to a second embodiment of the present invention. 6 is a flowchart showing a measurement method according to a second embodiment of the present invention. 4 is a captured image according to a second embodiment of the present invention. 6 is a surface shape image of an object to be measured according to a second embodiment of the present invention. It is a surface shape image of the to-be-measured object based on a prior art.

Explanation of symbols

3 ... Lattice
5 ... Object to be measured
10 ... Light source
11 ... 1st lens
15 ... Lattice drive unit
20… Image sensor
21 ... Second lens
23 ... Spatial filter
42… Stage drive unit
80 ... Stage
200 ... Imaging device controller
300, 400 ... CPU
309 ... Captured image input unit
310: Light intensity extraction unit
311… Bias erase operation section
312 ... Moire generation calculation unit
313: Phase calculation unit
314 ... Phase connection calculation unit
315 ... Correction calculation unit
316 ... Conversion operation unit
330 ... Program storage device
331 ... Data storage device
332 ... Memory grid storage device
340 ... Input device
341 ... Output device
350 ... Imaging device
411 ... Real part calculation part
412… Cosine function calculator
413 ... Initial phase calculation unit
432 ... Memory grid storage device

Claims (16)

An imaging device that projects a sinusoidal periodic bright and dark pattern having a first pitch on the object to be measured, and obtains a plurality of captured images having different phases of the object to be measured;
A bias component that has the same value as the vibration term that vibrates the light intensity of the pixels included in each of the plurality of captured images at a first frequency determined by the first pitch, and that determines the center value of the vibration. A plurality of sinusoidal functions each represented by the sum of the terms, and a light intensity extraction unit that assumes a plurality of light intensity functions with different phases including those that are 180 degrees different from each other ,
Bias for generating a plurality of combinations of two light intensity functions whose phases are different from each other by 180 degrees from the plurality of light intensity functions , subtracting each of the combinations to remove the bias component term , and calculating a plurality of basic functions An erasing operation section;
Each of the plurality of basic functions is a sinusoidal function whose phase is 90 degrees different from each other, and a product obtained by multiplying each of the plurality of memory lattice functions respectively oscillating at a second frequency determined by the second pitch, The frequency component term of the difference between the first frequency and the second frequency is converted into a format expressed by the sum of the frequency component term of the sum of the first frequency and the second frequency . A moire generation calculation unit for calculating a moire function;
Wherein the plurality of combinations of the two moire functions the same absolute value of the term of the frequency components of said sum together the moire function generates a plurality, is removed by calculation to offset the terms of the frequency components of said sum to each other in the combination, the A three-dimensional measuring apparatus comprising: a phase calculating unit that calculates an initial phase for reducing the number of phase unwrapping from the term of the frequency component of the difference remaining by the calculation. An imaging device that projects a sinusoidal periodic bright and dark pattern having a first pitch on the object to be measured, and obtains a plurality of captured images having different phases of the object to be measured;
A bias component that has the same value as the vibration term that vibrates the light intensity of the pixels included in each of the plurality of captured images at a first frequency determined by the first pitch, and that determines the center value of the vibration. A plurality of sinusoidal functions each represented by the sum of the terms, and a light intensity extraction unit that assumes a plurality of light intensity functions with different phases including those that are 180 degrees different from each other ,
A sine wave-like function each having a phase difference of 90 degrees, a memory grid storage device that stores a first memory grid function group and a second memory grid function group that respectively vibrate at a second frequency determined by the second pitch ;
A product obtained by multiplying each of the plurality of light intensity functions by each of a plurality of memory lattice functions included in each of the first memory lattice function group and the second memory lattice function group, and the first frequency, Sum of the frequency component term of the difference between the second frequencies, the frequency component term of the sum of the first frequency and the second frequency, and the second frequency component term having the bias component as an amplitude. A cosine function calculator that calculates a plurality of cosine functions and a plurality of sine functions,
Calculating a real part function by calculating a sum of the plurality of cosine functions and removing a term of the second frequency component having an amplitude of a frequency component and a bias component of the sum included in the plurality of cosine functions; The real part calculation unit that calculates the imaginary part function by removing the term of the second frequency component having the amplitude of the sum frequency component and the bias component included in the plurality of sine functions. When,
An initial phase calculating unit that calculates an initial phase for reducing the number of phase unwrapping from the frequency component term of the difference by dividing the imaginary part function by the real part function and taking an arc tangent. 3D measuring device.   3. The three-dimensional measurement apparatus according to claim 1, wherein a second pitch included in each of the plurality of memory lattice functions is larger than half of the first pitch.   3. The three-dimensional measurement apparatus according to claim 1, wherein the second pitch included in each of the plurality of memory lattice functions has a value equal to the first pitch. 4.   5. The three-dimensional image according to claim 1, wherein the imaging apparatus includes a lattice driving unit that sequentially moves the light and dark patterns in the same direction as the first pitch at equal intervals. 6. Measuring device.   5. The image pickup apparatus includes a grating driving unit that sequentially moves the light / dark pattern in the same direction as the first pitch by a distance of a quarter of the first pitch. 6. The three-dimensional measuring apparatus according to any one of the above. A periodic sinusoidal pattern having a first pitch is projected onto the measured object, and the captured image input unit acquires a plurality of captured images with different phases of the measured object, and stores them in the data storage device Steps,
The light intensity extraction unit has the same value as the vibration term that vibrates the light intensity of the pixels included in each of the plurality of captured images at the first frequency determined by the first pitch, and the center value of the vibration A plurality of sinusoidal functions each represented by the sum of the bias component terms that determine a plurality of light intensity functions , each including a phase that is 180 degrees different from each other, and the data storage Storing in the device;
The bias erasure calculation unit generates a plurality of combinations of two light intensity functions whose phases are different from each other by 180 degrees from the plurality of light intensity functions , performs subtraction in each of the combinations to remove a bias component term , and a plurality of basic functions Calculating and storing in the data storage device;
The moiré generation calculation unit multiplies each of the plurality of basic functions by a plurality of memory lattice functions each oscillating at a second frequency determined by the second pitch, which is a sinusoidal function having a phase difference of 90 degrees from each other. The product is expressed by the sum of the frequency component term of the difference between the first frequency and the second frequency and the frequency component term of the sum of the first frequency and the second frequency. Converting, calculating a plurality of moire functions, and storing in the data storage device;
By calculating the phase calculation unit combining a plurality generation of two moire functions the same absolute value of the term of the frequency components of the sum from each other from the plurality of moire functions, cancel each other section of the frequency components of the sum in the combination And a step of calculating an initial phase for reducing the number of phase unwrapping from the term of the frequency component of the difference remaining after the calculation. A periodic sinusoidal pattern having a first pitch is projected onto the measured object, and the captured image input unit acquires a plurality of captured images with different phases of the measured object, and stores them in the data storage device Steps,
The light intensity extraction unit has the same value as the vibration term that vibrates the light intensity of the pixels included in each of the plurality of captured images at the first frequency determined by the first pitch, and the center value of the vibration A plurality of sinusoidal functions each represented by the sum of the bias component terms that determine a plurality of light intensity functions , each including a phase that is 180 degrees different from each other, and the data storage Storing in the device;
The first cosine function is a sinusoidal function whose phase is 90 degrees different from each other for each of the plurality of light intensity functions , and a first memory lattice function that vibrates at a second frequency determined by a second pitch. A product obtained by multiplying each of a plurality of memory lattice functions included in each of the group and the second memory lattice function group, a term of a frequency component of a difference between the first frequency and the second frequency, and the first frequency And a plurality of cosine functions and a plurality of sine functions , which are converted into a form represented by the sum of the frequency component term of the sum of the second frequency and the second frequency component term having the bias component as an amplitude. Calculating and storing in the data storage device;
The real part calculation unit takes the sum of the plurality of cosine functions and the sum of the plurality of sine functions, thereby causing the frequency component and the bias component of the sum included in the plurality of cosine functions and sine functions to be amplitudes. Calculating the real part function and the imaginary part function by removing the frequency component term , and storing in the data storage device;
An initial phase calculation unit calculates an initial phase for reducing the number of phase unwraps from the frequency component term of the difference by dividing the imaginary part function by the real part function and taking an arc tangent. 3D measurement method characterized by including.   In the step of calculating the plurality of moire functions and storing them in the data storage device, a second pitch included in each of the plurality of memory lattice functions is greater than half of the first pitch. 8. The three-dimensional measurement method according to claim 7,   The second pitch included in each of the plurality of memory lattice functions is equal to the first pitch in the step of calculating and storing the plurality of moire functions in the data storage device. 7. The three-dimensional measuring method according to 7.   In the step of calculating the plurality of cosine functions and the plurality of sine functions and storing them in the data storage device, the second pitch included in each of the plurality of memory grid functions is more than half of the first pitch. The three-dimensional measurement method according to claim 8, wherein the three-dimensional measurement method is large.   In the step of calculating the plurality of cosine functions and the plurality of sine functions and storing them in the data storage device, a second pitch included in each of the plurality of memory lattice functions is equal to the first pitch. The three-dimensional measurement method according to claim 8, wherein   The step of acquiring a plurality of captured images having different phases and storing them in the data storage device includes a step of sequentially moving the light and dark pattern at equal intervals in the same direction as the first pitch. The three-dimensional measurement method according to any one of claims 7 to 12.   The step of acquiring a plurality of captured images having different phases and storing the captured images in the data storage device sequentially sets the bright and dark patterns to a distance of a quarter of the first pitch in the same direction as the first pitch. The three-dimensional measurement method according to claim 7, further comprising a moving procedure. A three-dimensional measurement program for driving and controlling a three-dimensional measurement apparatus for measuring the surface shape of an object to be measured.
A command for projecting a sinusoidal periodic bright and dark pattern having a first pitch on the object to be measured, and obtaining a plurality of captured images having different phases of the object to be measured;
A bias component that has the same value as the vibration term that vibrates the light intensity of the pixels included in each of the plurality of captured images at a first frequency determined by the first pitch, and that determines the center value of the vibration. A plurality of sinusoidal functions each represented by the sum of the terms, and a command that assumes a plurality of light intensity functions having different phases including those that are 180 degrees different from each other ;
Generating a plurality of combinations of two light intensity functions having phases different from each other by 180 degrees from the plurality of light intensity functions , executing a subtraction in each of the combinations to remove a bias component term , and calculating a plurality of basic functions; ,
Each of the plurality of basic functions is a sinusoidal function whose phase is 90 degrees different from each other, and a product obtained by multiplying each of the plurality of memory lattice functions respectively oscillating at a second frequency determined by the second pitch, The frequency component term of the difference between the first frequency and the second frequency is converted into a format expressed by the sum of the frequency component term of the sum of the first frequency and the second frequency . An instruction to calculate the moiré function;
Wherein the plurality of combinations of the two moire functions the same absolute value of the term of the frequency components of the sum to each other from the moire function generates a plurality, is removed by calculation to offset the terms of the frequency components of said sum to each other in the combination, the operation And a command for calculating an initial phase for reducing the number of phase unwrapping from the term of the frequency component of the difference remaining in step ( 3). A three-dimensional measurement program for driving and controlling a three-dimensional measurement apparatus for measuring the surface shape of an object to be measured.
A command for projecting a sinusoidal periodic bright and dark pattern having a first pitch on the object to be measured, and obtaining a plurality of captured images having different phases of the object to be measured;
A bias component that has the same value as the vibration term that vibrates the light intensity of the pixels included in each of the plurality of captured images at a first frequency determined by the first pitch, and that determines the center value of the vibration. A plurality of sinusoidal functions each represented by the sum of the terms, and a command that assumes a plurality of light intensity functions having different phases including those that are 180 degrees different from each other ;
A first memory lattice function group and a second memory lattice , which are sinusoidal functions having phases different from each other by 90 degrees with respect to each of the plurality of light intensity functions, and respectively vibrate at a second frequency determined by the second pitch. A product obtained by multiplying each of the plurality of memory lattice functions included in each of the function groups is a term of a frequency component of a difference between the first frequency and the second frequency, the first frequency, and the second frequency. An instruction for calculating a plurality of cosine functions and a plurality of sine functions by converting to a form represented by a sum of the frequency component term of the sum of the two and the term of the second frequency component having the bias component as an amplitude ;
The term of the second frequency component having the amplitude of the frequency component and the bias component of the sum included in the plurality of cosine functions and the sine function by taking the sum of the plurality of cosine functions and the sum of the plurality of sine functions. To calculate each of the real part function and the imaginary part function by removing
Dividing the imaginary part function by the real part function and taking an arc tangent to execute an instruction for calculating an initial phase for reducing the number of phase unwrapping from the frequency component term of the difference A three-dimensional measurement program.