JPH07280535A - Three-dimensional shape measuring apparatus - Google Patents

Abstract

PURPOSE:To provide an apparatus which enables non-contact precise measurement of the three-dimensional shape of an object. CONSTITUTION:A luminous flux of a light source 101 is divided in two according to the direction of polarization using a polarization separating element 102. With a wave front thereof inclined, the luminous fluxes are overlapped to form an interference fringe 106 on an object 05 to be measured and observed askew to measure the deformation of the interference fringe. Then, a phase difference of polarization is changed with a phase modulation element to calculate a phase value of the interference fringe from a plurality of image data. Hence, a precision measurement is carried out. Moreover, a light source light is used with a lower coherence to suppress a speckle noise and a range of receiving wave of an image detector 108 and photodetecting time are limited thereby reducing effect from ambient light.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for measuring the three-dimensional shape of an object in a non-contact manner.

[0002]

2. Description of the Related Art Conventionally, in order to measure a three-dimensional shape of an object in a non-contact manner, a light cutting method, a moire topography method, a grid pattern projection method, a stripe scanning method and the like have been used.

The light-section method is to irradiate an object with a slit-shaped light beam, observe a portion on which the light hits obliquely, and obtain a three-dimensional shape from the deformation of the irradiated light beam.

In order to obtain the overall shape of the object, it is necessary to scan the light beam, which has the drawback that the measurement takes time.

The moiré topography method is a method of projecting a grid pattern on an object, determining the deformation of the grid that occurs at that time by observing the moiré with the reference grid, and displaying the contour lines of the object.

In the conventional moire topography method, 1 contour lines are not equidistant. 2 Higher-order moiré is generated and noise is generated. 3 It is not possible to measure accurately between moire fringes. However, it is good for visual observation, but not suitable for computer processing. Further, if it is premised on the processing by the computer, it is not necessary to observe the moire, and it is sufficient to observe the deformation of the projected stripes.

The lattice pattern projection method can be considered as a method in which a large number of light beams of the light cutting method are arranged and irradiated to an object, and the time is shortened as compared with the light cutting method.

However, there is a drawback that the measurement is possible only at the boundary or center of the grid pattern and the spatial resolution is poor, and it is difficult to distinguish between the pattern on the surface of the object and the grid pattern, which may lower the measurement accuracy. is there.

Therefore, in order to improve the measurement accuracy and perform the processing suitable for the computer, the lattice plate used in the lattice pattern projection method is moved to observe a plurality of images, and the three-dimensional measurement is performed by the arithmetic processing. A method is proposed in Japanese Patent Laid-Open No. 4-9811. Figure 9 is column 10 of this specification
It is a block diagram of the principal part of invention described from the line to 12 columns and 2 lines, and FIG. Light from the light source 901 is collected by the condenser lens 9
No. 02, through the grating plate 903 and on the measuring object 907 by the illumination lens 906.
8 is projected. In this device, the light source 901 is a grating 903.
Since it is only used for projecting, a normal white light source can be used. The grating pattern 908 projected on the measurement object 907 is imaged on the image detection device 910 by the imaging lens 909, and the image input / output device 911.
The image data is sent to the analysis device 912 through and the three-dimensional shape of the measurement object 907 is calculated. The grid plate 903 is a motor 9 controlled by a motor driving device 905.
By 04, it is moved in the direction perpendicular to the optical axis by 1/4 of the pitch of the grating pattern, and is analyzed by the fringe scanning method based on the plurality of image data obtained each time.

However, in this case, since the rectangular wave pattern is used as the pattern projected on the object, there is no change in brightness within the same stripe, and the accuracy is poor. Also,
Since the projection grid is moved by a motor, there are drawbacks such as vibrations and inaccurate movement due to gear backlash.

Further, instead of projecting the grating pattern, an interference fringe having a sinusoidal intensity distribution is generated by an interferometer, and the phase difference amount of the interfering wavefront is changed to move the fringe on the object, A method for obtaining the shape by a method similar to the scanning method has been developed. (Satoshi Kakuuchi, Koichi Iwata, Motoyuki Hasegawa, Shinji Yamaguchi: "Three-dimensional shape measurement by stripe scanning interference fringe projection method", Journal of Japan Society for Precision Industry, Vol.
55, No. 1, (1989)) (Reference 1) FIG. 10 is a block diagram of this measuring apparatus. The luminous flux of the laser light source 1001 is oscillated by the half prism 1002 into a vibrating mirror 1003.
And a fixed mirror 1006. Vibrating mirror 100
2 is a PZT controlled by the PZT driving device 1005
It is fixed to 1004 and is moved a minute distance by a signal from the analysis device 1013. The fixed mirror 1006 is inclined by δ with respect to the optical axis and gives an inclination to the wavefront.
The light reflected by each mirror is a half prism 1002.
Are collected again by the illumination lens 1007 to form interference fringes 1009 on the measurement object 1008. Measuring object 10
The interference fringes 1009 formed on 08 are the imaging lenses 101.
0, an image is formed on the image detection device 1011 and the image data is passed through the image input / output device 1012.
13 and the three-dimensional shape of the measurement object 1008 is calculated. The vibrating mirror 1003 is moved in the optical axis direction by λ / 8 (λ is the wavelength of the light source), and is analyzed by the method of the fringe scanning method based on a plurality of image data obtained each time.

However, when a laser with good coherence is used as the light source of the interferometer, a speckle pattern is generated in the projected fringes, which causes noise and deteriorates the measurement accuracy. In addition, in order to change the phase difference amount of the interference wavefront, PZT
Since the mirror is moved by such as, there is a change over time,
Due to the hysteresis characteristic of PZT, the precision of the amount of phase difference has deteriorated. Furthermore, since the amount of phase difference is less than or equal to the wavelength, it is necessary for the interferometer to be in a stable state, and a seismic isolation device is indispensable.

[0013]

[Problems to be Solved by the Invention] As described above,
The light-section method has a drawback that it requires scanning a light beam and takes a long time for measurement. Further, the conventional moire topography method has a problem in that contour lines are not at regular intervals and noise is generated due to higher moire, so that the distance between moire fringes cannot be accurately measured. In addition, the grid pattern projection method has a drawback that measurement can be performed only at the boundary or center of the grid pattern, the spatial resolution is poor, and it is difficult to distinguish the pattern on the surface of the object from the grid pattern, which reduces the measurement accuracy. In addition, JP 4-
In the improved grid pattern projection method according to Japanese Patent Publication No. 9811, the measurement accuracy is poor because the brightness does not change in the same stripe, and since the projection grid is moved by the motor, vibrations or gear backlash may occur. However, there are drawbacks such as inaccurate movement amount. Further, in the stripe scanning interference fringe projection method, a speckle pattern is generated on the projected fringes, which causes noise and deteriorates the measurement accuracy, or the accuracy of the phase difference amount is improved by the hysteresis characteristic of PZT that changes the phase difference amount of the interference wavefront. It was getting worse. Furthermore, since the amount of phase difference is less than or equal to the wavelength, it is necessary for the interferometer to be in a stable state, and a seismic isolation device is indispensable.

A first object of the present invention is to obtain a three-dimensional measuring device which solves the above-mentioned drawbacks of the prior art. 1) The measuring time is short. (1 second or less) 2 High spatial resolution. (Approximately 1/500 of the measurement area) 3 It is not affected by ambient light or vibration, and can be used in any measurement environment.

It is to obtain a three-dimensional measuring device having the above characteristics.

Further, the second object of the present invention is: 1. High measurement accuracy. (Approximately 0.1% of the measurement range) 2 There are no mechanical moving parts that affect measurement, so maintenance and management are easy.

No high voltage power supply such as 3 PZT drive power supply is required.

4 No need for a seismic isolation device, and the device is small.

It is to obtain a three-dimensional measuring device having the characteristics as described above.

[0020]

In order to obtain the required characteristics, the present inventor has decided to improve the conventional interference fringe projection method on the assumption that a computer is used. Therefore, the three-dimensional measuring apparatus of the present invention separates a light source device that emits coherent light to the object to be measured and a light beam emitted from the light source means into two linearly polarized lights whose vibration directions are orthogonal to each other, A polarization interference device including a polarization separation element that imparts an inclination to at least one wavefront of the two linearly polarized lights, and an analyzer that causes interference fringes in overlapping light fluxes, and interference projected on the object to be measured. It is characterized by comprising an observing device for observing stripes and an analyzing means for calculating a three-dimensional shape of the object to be measured from the shape of the fringes observed by the observing device.

Further, the polarization separation element in the above-mentioned polarization interference device comprises a polarization beam splitter, a λ / 4 wavelength plate and a plane mirror, and is bonded to each other.

Further, the polarization separation element in the polarization interference device is a prism in which at least two uniaxial optical crystals are bonded together.

Further, it is characterized by including a phase difference amount changing device capable of changing the mutual phase difference amount of the linearly polarized light divided into two by the polarization interference device.

Further, as the phase difference changing device,
A feature is that a phase modulation element including a liquid crystal element, an electro-optical element, or a magneto-optical element, and a phase modulation element driving device that drives the phase modulation element are used.

Further, a light source device having a wavelength width of 1 nm or more and 100 nm or less is used.

Further, as the light source device, a laser diode or a super luminescent diode and a phase difference compensating plate are used.

Further, a narrow band filter matched to the wavelength of the light source is provided in front of the observation device.

Further, using a light source which emits light in a pulse shape,
It is characterized in that the light receiving timing of the observation device is matched with the light emitting time of the light source.

[0029]

The principle of the present invention will be described below with reference to the drawings.

The present invention improves the conventional interference fringe projection method on the assumption that a computer is used, and divides the wavefront by polarized light to form interference fringes. FIG. 1 is a block diagram of an apparatus showing the principle of the present invention. In this figure, 101 is a light source that emits coherent light. The polarization beam splitting element 102 refracts linearly polarized light vibrating in the direction perpendicular to the paper surface and linearly polarized light vibrating in the horizontal direction at different angles to give an inclination to the wavefront. The light beams converted by the analyzer 103 into linearly polarized light in the direction of 45 ° become coherent and form interference fringes in the overlapped portion. The polarization separation device 102 and the analyzer 103 constitute a polarization interference device that causes interference fringes. The light flux whose width has been expanded by the illumination lens 104 projects an interference fringe 106 on the measurement object 105. The image detection device 108 constitutes an observation device together with the imaging lens 107,
The interference fringe 106 on the measurement object 105 is imaged on the image detection device 108 by the imaging lens 107. The image information obtained by the image detection device 108 is the image input device 109.
Is sent to the analysis device 110, and the three-dimensional shape of the measurement object 105 is restored by arithmetic processing. At this time, one interference fringe is formed in a plane forming an angle α with the optical axis of the projection optical system. Since the relationship between the interference fringes and the angle α is determined by the device, the three-dimensional coordinates of the point P can be obtained by finding the intersection of the direction of the point P and the plane of the angle α which can be known from the image information.

The light source may be any light source that emits coherent light, but the fact that equal amounts of linearly polarized light components in the vertical and horizontal directions relative to the paper surface improves the contrast of interference fringes. Desirable for this. For that purpose, when the light source is randomly polarized light, circularly polarized light, or the like, an analyzer may be placed immediately after the light source, and the transmitted light may be linearly polarized light vibrating in the direction of 45 degrees with respect to the paper surface.

Further, in order to suppress speckle noise, it is preferable to use a light source with a short coherence length. in this case,
It is desirable to use a phase difference compensator to compensate for the phase difference between the polarized lights. By using a mercury lamp, LD (laser diode), SLD (super luminescent diode), etc. with a half-width of wavelength of 1 nm or more, speckle noise of scattered light can be reduced and highly accurate measurement can be performed. . The SLD is a high-precision incoherent light source in which the emission surface of the LD is coated with an antireflection film to stop laser oscillation and generate superradiance. Further, a white light source having a wavelength width of 100 nm or more is not suitable as a light source because the contrast of interference fringes deteriorates. That is, in the present invention, a light source device having a wavelength width of 1 nm or more and 100 nm or less is preferably used.

The polarization splitting element splits the incident light flux into two linearly polarized lights whose vibration directions are orthogonal to each other, and has a function of inclining the wavefront. This includes a polarization beam splitter 201, λ / 4 plates 202 and 203 and a plane mirror 20 as shown in FIG.
A device in which 4,205 are combined can be used.
The linearly polarized light that has entered the polarization beam splitter 201 and is vibrating in the horizontal direction with respect to the paper surface is transmitted through the joint surface of the prism, and the linearly polarized light in the vertical direction is reflected. The light transmitted through the polarization beam splitter 201 is λ / 4 plate 202.
And is converted from linearly polarized light to circularly polarized light. Then, it is reflected by the plane mirror 204, and again the λ / 4 plate 20.
2 is transmitted, and circularly polarized light is converted into linearly polarized light. At this time, the vibration direction of the linearly polarized light is rotated by 90 degrees and vibrates in the direction perpendicular to the paper surface. Therefore, the light is reflected by the joint surface of the prism and is emitted to the object side. Similarly, linearly polarized light vibrating in the direction perpendicular to the paper surface is reflected by the joint surface of the prism, transmitted through the λ / 4 plate 203, and converted from linearly polarized light to circularly polarized light. Then, the light is reflected by the plane mirror 205, passes through the λ / 4 plate 203 again, and is converted from circularly polarized light into linearly polarized light. At this time, the vibration direction of the linearly polarized light is rotated by 90 degrees and vibrates in the horizontal direction with respect to the paper surface. Therefore, the light is transmitted through the joint surface of the prism and is emitted to the object side. By tilting one of the plane mirrors with respect to the optical axis, the wavefront can be tilted. The interference fringe projection method of FIG. 10 described above also uses the same wavefront dividing element, but in this case, since the mirror needs to be moved for fringe scanning, the beam splitter and the mirror must be separated. . However, in the case of the present invention, since it is not necessary to move the mirror, in order to avoid the influence of vibration, as shown in FIG.
It is desirable that the 4λ plates 302 and 303 and the plane mirrors 304 and 305 be bonded and fixed to the polarization beam splitter 301. At this time, the plane mirrors 304 and 305 can be omitted by vapor-depositing the emission surfaces of the λ / 4 plates 302 and 303 to form reflecting surfaces.

Further, as the polarization separating element, a prism in which two or more uniaxial optical crystals such as quartz or calcite are laminated may be used. As such a prism, the Wollaston prism 401 shown in FIG. 4 and the Rochon prism 501 shown in FIG. 5 are often used. The uniaxial optical crystal is a material whose refractive index changes depending on the polarization direction of the incident light beam. Therefore, the light beam transmitted through the prism has a different refraction angle depending on the polarization direction, and the wavefront is inclined by φ.

The analyzer is an element that transmits only linearly polarized light in one direction by utilizing the difference in dichroism and refractive index of the optical crystal. There are Glan-Thompson prisms and Nicol prisms in which uniaxial optical crystals are attached, but polarizing plates in which iodine crystals are adsorbed on a polymer film are widely used because of their ease of use and wide field of view.

Further, in order to reduce the influence of external light, the light source light is emitted in a pulsed manner and the light receiving timing of the image detection device 108 is adjusted to this, or the wavelength of the light source light is adjusted before the observation device. Put a narrow band filter. In this way, the influence of ambient light can be minimized.

By using the three-dimensional shape measuring device comprising the devices shown in claims 1 to 3 and 8 and 9 as described above,
The third object of the present invention, which has the first object of the present invention, is that the measurement time is short, the spatial resolution is high, and that the measurement environment is not affected by ambient light or vibration. The original measuring device can be obtained.

Furthermore, using this device, the second object of the present invention is "high measurement accuracy.""There is no mechanical moving part that affects measurement, and maintenance and management are easy." P
A high-voltage power supply such as a ZT drive power supply is unnecessary. In order to obtain a three-dimensional measuring device having the features such as "no need for a vibration eliminator, the device is small", a phase difference changing device is used between the light source 101 and the polarization separation element 102 in FIG. Or
It is placed between the polarization separation element 102 and the analyzer 103. The phase difference amount changing device is a device that changes the relative phase difference amount of polarized light in the horizontal direction and the vertical direction with respect to the paper surface, and observes multiple images while changing the phase difference amount by the phase difference amount changing device. The phase of the interference fringes is calculated by the scanning method, and the three-dimensional shape of the object is calculated.

As the phase difference amount changing device, a plurality of phase difference plates made of a uniaxial optical crystal can be switched and used, or a Babinet Soleil phase plate as shown in FIG. 6 can be used. The Babinet Soleil's phase plate is made of a prism of uniaxial optical crystals such as quartz, and has two parallel optical axes.
It consists of a wedge and a plane-parallel plate whose optical axis direction is perpendicular to it. By moving one wedge in the direction of the arrow in the figure, the phase difference between the linearly polarized light components in which the vibration directions transmitted are orthogonal to each other It can be any value.

Further, a liquid crystal element oriented in an EBC (electric field control birefringence) mode, an electro-optical element such as ADP or KDP, or a phase modulation element such as a magneto-optical element is controlled by a phase modulation element driving device. It can also be used as a phase difference changing device. By using a phase modulation element controlled by voltage or magnetic field by utilizing these electro-optical effects,
It is possible to obtain a phase difference amount changing device which has no mechanically movable parts, is resistant to vibration, and has little change over time. In particular, when a liquid crystal element is used, a high-voltage power supply is not required and a simple device is obtained as compared with the case where other elements are used.

Even when the phase difference changing device is inserted for high precision measurement, one interference fringe is formed in the plane forming the angle α with the optical axis. Since the relationship between the phase amount Ψ (α) of interference fringes and α is determined by the device, α can be calculated if Ψ (α) is known.
Then, the three-dimensional coordinates of the point P can be calculated by obtaining the intersection of the direction of the point P, which is known from the image information, and the plane of the equal phase amount.

The phase amount Ψ (α) is obtained by the fringe scanning method as follows. The intensity distribution I (α) of the interference fringes projected on the measurement object has a wave number k = 2π / λ (λ is a wavelength),
Let ω be the phase difference of polarized light

[0043]

[Equation 1]

It is Now, when the phase difference ω is changed from 0 to λ at equal intervals in N steps, the observed interference fringe intensity I _n (α) is ω _n = nλ / N (n = 0, 1, ...). , N-
Put 1),

[0045]

[Equation 2]

It becomes

When I _n (α) is multiplied by cos (2πn / N) and the sum is obtained from n = 0 to N−1, F is obtained.

[0048]

[Equation 3]

And I _n (α) is sin (2πn / N)
Let G be the product of n and N-1.

[0050]

[Equation 4]

It is

Therefore, the phase amount Ψ (α) is given by Ψ (α) = tan ⁻¹ (G (α) / F (α)). In particular, in the case of N = 4, Ψ (α) = tan ⁻¹ ((I ₁ −I ₃ ) / (I ₀ −I ₂ )) becomes simple.

The value of the phase amount Ψ (α) thus obtained is ± π
Since it is limited to the range of, Ψ calculated in consideration of the shape continuity of the measured object in order to measure the range beyond
2π may be added or subtracted appropriately to the value of (α). Letting p be the angular pitch of the interference fringes, α = p (Ψ (α) −Ψ ₀ + 2πm)
Α is calculated by / 2π (m is an appropriate natural number determined so that Ψ (α) is continuous). By performing such fringe scanning, the phase can be obtained with an accuracy of several hundredths of 2π. Therefore, α can be obtained with an accuracy of several hundredths of p. The angular pitch p of the interference fringes is determined by the separation angle φ of the polarization separation element 102 and the focal length of the illumination lens 104,
If the illumination lens 104 is a zoom lens, it can be changed continuously.

By using the above-mentioned device, the second object of the present invention is "high measurement accuracy""no mechanical moving parts affecting the measurement, and maintenance and management are easy. It is possible to obtain a three-dimensional measuring device having features such as "No high voltage power source such as PZT drive power source is required."

The three-dimensional shape measuring apparatus according to the present invention is particularly effective for measuring the shape of a human body or a mockup model because it can perform high-precision measurement in a short time without contact.

[0056]

【Example】

Example 1 FIG. 7 is a configuration diagram of Example 1 of the present invention. In this figure, the light emitted from the LD light source 701, which is a light source, becomes a parallel light flux by the collimator lens 703, passes through the phase difference compensating plate 704, and causes an optical path difference caused by a phase modulation element 705 and a Wollaston prism 707 described later. The wavelength is compensated. Furthermore, the phase modulator 7
By 05, an arbitrary phase difference amount can be given between the polarized light perpendicular to the paper surface and the polarized light horizontal to the paper surface. Here, a case where a liquid crystal element is used as the phase modulation element 705 is illustrated, and the phase modulation element 705 and the phase modulation element driving device 706 are
It constitutes a phase amount changing device. The polarized light in both directions is separated by the Wollaston prism 707, and the wavefront is tilted. Then, by the polarizing plate 708, the
The light beam converted to 5 ° linearly polarized light becomes coherent.
In this case, the Wollaston prism 707 and the polarizing plate 708
This constitutes a polarization interference device. The luminous flux is the illumination lens 7
09, and the interference fringes 7 are spread on the measuring object 710.
11 is formed. The interference fringes 711 on the measurement object 710 are imaged on the image detection device 714 by the imaging lens 713. The image detection device 714 constitutes an imaging lens 713 and an observation device. The obtained image information is sent to the analysis device 716 by the image input device 715, and the three-dimensional shape of the measurement object 710 is restored by arithmetic processing. It At this time, the equiphase surface of the interference fringes is in a plane that makes an angle α with the optical axis, and the relationship between the phase amount Ψ (α) and the angle α is determined by the device. Therefore, α can be found by obtaining Ψ (α). The value of Ψ (α) is obtained by the fringe scanning method by observing a plurality of images while controlling the phase difference amount of polarized light by the phase modulation element 705. The three-dimensional coordinates of the point P can be obtained by finding the intersection of the direction of the point P and the equiphase surface of Ψ (α) which is known from the image information.

Further, the LD light source 701 is connected to the LD driving device 7
02 to emit light in a pulse shape, and the image detecting device 714
By adjusting the light receiving timing of (1) and the narrow band filter 712 that matches the wavelength of the light source light in front of the observation device, the influence of ambient light is minimized and the measurement accuracy is improved.

(Second Embodiment) FIG. 8 is a configuration diagram of a second embodiment of the present invention. In this figure, the light emitted from the laser light source 801 passes through the phase difference compensating plate 802, and the optical path difference generated by the phase modulation element 803 and the Wollaston prism 805, which will be described later, is compensated up to about the wavelength. Further, the phase modulation element 803 can provide an arbitrary amount of phase difference between the polarized light perpendicular to the paper surface and the polarized light horizontal to the paper surface. The polarized light in both directions is separated by the Wollaston prism 805, and the wavefront is tilted. 4 by the polarizing plate 806
The light flux converted to linearly polarized light in the 5 ° direction becomes coherent,
The width of the light flux is expanded by the illumination lenses 807 and 808, and interference fringes 810 are formed on the measurement object 809. The interference fringe 810 on the measurement object 809 is imaged on the image detection device 812 by the imaging lens 811. The image detection device 812 constitutes an imaging lens 811 and an observation device, and the obtained image information is sent to the analysis device 814 through the image input device 813, and the measurement object 80 is calculated by the arithmetic processing.
The three-dimensional shape of 9 is restored. At this time, the phase modulator 8
A plurality of images are observed while controlling the phase difference amount by 03, the phase amount of the interference fringes is calculated by the fringe scanning method, and the three-dimensional shape of the object is calculated, thereby performing highly accurate measurement.

As shown in FIG. 8, when the measurement object 809 is irradiated with light from the light source as a parallel light flux, interference fringes are formed in a plane perpendicular to the x axis in the figure. In this case, the illumination lens 807,
Reference numeral 808 denotes a telecentric optical system, and the relationship between the phase amount Ψ (x) of the interference fringes and the x coordinate does not change depending on the distance between the measurement object 809 and the interference fringes projection optical system, and the separation angle φ of the Wollaston prism 805. And illumination lens 807,80
Determined by a magnification of 8. Therefore, if Ψ (x) is known, x can be calculated, and the three-dimensional coordinates of the point P can be calculated by finding the intersection of the direction of the point P known from the image information and the plane of the equal phase amount. By thus forming the illumination lenses 807 and 808 in the telecentric optical system, it is possible to eliminate the influence of the positional accuracy of the illumination optical system on the shape measurement accuracy.

[0060]

According to the invention described in claim 1, 1 the measurement time is short. (1 second or less) 2 High spatial resolution. (Approximately 1/500 of the measurement area) 3 It is not affected by ambient light or vibration, and can be used in any measurement environment.

It is possible to provide a three-dimensional shape measuring apparatus having the effects described above.

According to the invention of claim 4, 1) the measurement accuracy is high. (Approximately 0.1% of the measurement range) 2 There are no mechanical moving parts that affect measurement, so maintenance and management are easy.

3 No need for a high voltage power source such as a PZT drive power source.

4 A seismic isolation device is unnecessary, and the device is compact.

It is possible to provide a three-dimensional shape measuring apparatus having the effects described above.

[Brief description of drawings]

FIG. 1 is an explanatory view of the principle of the present invention.

FIG. 2 is a configuration diagram of a polarization separation prism.

FIG. 3 is a configuration diagram in which the respective elements of the polarization separation prism are joined together.

FIG. 4 is a block diagram of a Wollaston prism.

FIG. 5 is a block diagram of a lotion prism.

FIG. 6 is a block diagram of a phase plate of Babinet Soleil.

FIG. 7 is a configuration diagram of the first embodiment of the present application.

FIG. 8 is a configuration diagram of a second embodiment of the present application.

FIG. 9 is a configuration diagram of a conventional fringe scanning method.

FIG. 10 is a configuration diagram of a conventional interference fringe scanning method.

[Explanation of symbols]

 101 ・ ・ ・ Light source 102 ・ ・ ・ Polarization separation element 103 ・ ・ ・ Analyzer 104 ・ ・ ・ Illumination lens 105 ・ ・ ・ Measuring object 106 ・ ・ ・ Interference fringes 107 ・ ・ ・ Imaging lens 108 ・ ・ ・ Image detection device 109 ・ ・ ・ Image input device 110 ・ ・ ・ Analyzing device 201 ・ ・ ・ Polarizing beam splitter 202, 203 ・ ・ ・ λ / 4 wavelength plate 204, 205 ・ ・ ・ Plane mirror 301 ・ ・ ・ Polarizing beam splitter 302, 303 ・ ・・ Λ / 4 wavelength plate 304, 305 ・ ・ ・ Plane mirror 401 ・ ・ ・ Wollaston prism 501 ・ ・ ・ Rochon prism 601 ・ ・ ・ Fixed wedge prism 602 ・ ・ ・ Moving wedge prism 603 ・ ・ ・ Parallel plane plate 701 ・ ・ ・LD light source 702 ・ ・ ・ LD drive device 703 ・ ・ ・ Collimate lens 704 ・ ・ ・Difference compensation plate 705 ... Phase modulation element 706 ... Phase modulation element driving device 707 ... Wollaston prism 708 ... Polarizing plate 709 ... Illumination lens 710 ... Measurement object 711 ... Interference fringes 712 ... Narrow band filter 713 ... Imaging lens 714 ... Image detection device 715 ... Image input device 716 ... Analysis device 801 ... Laser light source 802 ... Phase difference compensation plate 803 ... .. Phase modulation element 804 ... Phase modulation element driving device 805 ... Wollaston prism 806 ... Polarizing plates 807, 808 ... Illumination lens 809 ... Measurement object 810 ... Interference fringe 811 ... Image forming lens 812 Image detecting device 813 Image input device 814 Analyzing device 901 White light source 902 ... Condensing lens 903 ... Lattice plate 904 ... Motor 905 ... Motor drive device 906 ... Illumination lens 907 ... Measuring object 908 ... Lattice pattern 909 ... Image lens 910 Image detection device 911 Image input device 912 Analysis device 1001 Laser light source 1002 Half prism 1003 Vibratory mirror 1004 PZT 1005 PZT Drive device 1006 ・ ・ ・ Fixed mirror 1007 ・ ・ ・ Illumination lens 1008 ・ ・ ・ Measurement object 1009 ・ ・ ・ Interference fringes 1010 ・ ・ ・ Imaging lens 1011 ・ ・ ・ Image detection device 1012 ・ ・ ・ Image input device 1013 ・ ・・ Analyzer

Claims (9)

[Claims] 1. A three-dimensional shape measuring apparatus for measuring a shape of an object to be measured by projecting a predetermined pattern on the object to be measured having a three-dimensional shape, the light source emitting coherent light to the object to be measured. A device and a polarization beam splitting element for splitting a light beam emitted from the light source means into two linearly polarized lights whose vibration directions are orthogonal to each other, and giving an inclination to at least one wavefront of the two linearly polarized lights,
A polarization interference device composed of an analyzer that causes interference fringes in the overlapping light fluxes, an observation device that observes the interference fringes projected on the object to be measured, and from the shape of the fringes observed by the observation device, A three-dimensional shape measuring apparatus, comprising: an analyzing unit that calculates a three-dimensional shape of an object to be measured. 2. The three-dimensional shape measuring apparatus according to claim 1, wherein the polarization beam splitting element is composed of a polarization beam splitter, a λ / 4 wavelength plate, and a plane mirror, which are adhered to each other. 3. The three-dimensional shape measuring apparatus according to claim 1, wherein the polarization separation element is a prism in which at least two uniaxial optical crystals are bonded together. 4. The three-dimensional shape measuring apparatus according to claim 1, further comprising a phase difference amount changing device capable of changing a mutual phase difference amount of linearly polarized light divided into two by the polarization interference device. 5. A phase modulation element composed of a liquid crystal element, an electro-optical element, or a magneto-optical element, and a phase modulation element driving device for driving the phase modulation element are used as the phase difference amount changing device. The three-dimensional shape measuring apparatus according to claim 4. 6. The three-dimensional shape measuring apparatus according to claim 1, wherein the luminous flux emitted from the light source device has a wavelength width of 1 nm or more and 100 nm or less. 7. The three-dimensional shape measuring device according to claim 6, wherein a laser diode or a super luminescent diode and a phase difference compensating plate are used as the light source device. 8. The three-dimensional shape measuring apparatus according to claim 1, further comprising a narrow band filter matched to a wavelength of a light beam emitted from the light source apparatus, in front of the observation apparatus. 9. The three-dimensional shape measuring apparatus according to claim 1, wherein a light source means that emits light in a pulse shape is used as the light source device, and the light receiving timing of the observation device is matched with the light emission time of the light source means.