TW202326068A - Method and Apparatus for Measuring Three-Dimensional Composite Surface Profile of Object - Google Patents

Abstract

A method for measuring a three-dimensional composite surface profile of an object includes: (a) projecting an image to a sample through at least one group of a fringe projection device; (b) recording a wave front of the reflected light of the sample through a digital holographic access unit; (c) reconstructing the reflected light of a specular surface of the sample and its three-dimensional profile information through a digital holographic reconstruction method; (d) reconstructing the phase image and three-dimensional profile information of the diffused surface of the sample through a fringe projection analysis method; and (e) performing an image alignment of the three-dimensional image of the specular surface and the diffused surface through an image fitting technology to complete the full-scale image of a composite surface with the specular surface and the diffused surface and its three-dimensional contour reconstruction.

Description

Method and device for measuring three-dimensional composite surface profile of an object

The present invention relates to the measurement of the surface of objects, especially a combination of digital holography and fringe projection technology in a single optical measurement system to reconstruct digital holography (Digital Holography: DH) and fringe projection (Fringe Projection: FP) images Apparatus and method for three-dimensional composite surface contour distribution of an object.

Today's laser optoelectronic technology is changing and progressing rapidly, and biomedical imaging technology combined with optoelectronic technology will become an emerging industry that is widely expected in the future. For example, new breakthroughs have been made through the imaging research of biomedical cells, or the use of laser beams as a treatment method. In the past ten years, the performance of pulsed laser (pulsed laser) in terms of pulse width, pulse energy and pulse wavelength tuning range has been greatly improved, making the overall stability and ease of ultra-short pulsed laser (ultra-short pulsed laser) system Operability and other aspects have been greatly improved. Prospective applications such as laser surgery (Photodisruption), photodynamic therapy (Photodynamic therapy) and optogenetics (Optogenetics) have also been developed in the field of biomedicine. In order to provide more complete and accurate biomedical imaging information, 3D imaging technology has become a test and development trend of today's development.

In addition, with the rapid development of science and technology, the cost of hardware equipment has been reduced and the computing speed of computer equipment has been improved. The accuracy and contour integrity of products have been paid more and more attention. Optical 3D imaging is an indispensable tool for exploring precise 3D surface contours. . Different from the contact measurement where the probe touches the surface of the object to be measured for scanning, the fringe projection technology uses a non-contact and easy-to-operate measurement method, so that many micro components can avoid surface damage due to contact measurement. Destruction, coupled with the rapid development of high-speed image sensors and digital technology in recent years, has made fringe projection measurement one of the most widely used techniques for 3D surface measurement.

However, when the measurement has a very high/weak diffused surface, the 3D outline of the object cannot be accurately reconstructed due to the inability to obtain correct fringe deformation information, which reduces the applicability of the fringe projection technology. Therefore, many research groups have proposed studies on eliminating the phase error of extremely diffuse surfaces. For example, spraying a thin layer of powder on the surface of an object with a highly reflective surface reduces its reflectivity, thereby facilitating 3D surface measurement using fringe projection techniques. However, such a procedure is time-consuming and laborious, and the measurement accuracy is affected by the coating powder thickness.

Since the system cannot obtain the complete fringe of the object due to the measurement of the overly strong/weak diffuse surface, the correct phase information cannot be obtained, and there is currently no effective and reliable measurement method on the market to measure the specular surface ( composite surface object of specular surface) and diffuse surface. Therefore, the present invention develops a novel optical measurement method to solve and overcome the above-mentioned problems.

In view of the fact that it is difficult to measure the composite surface object with specular surface and diffuse surface at the same time; therefore, the present invention proposes to use digital holography combined with fringe projection technology to measure and reconstruct the image of the composite surface object.

The three-dimensional composite surface imaging and measurement method of the present invention can be applied to three-dimensional contour detection of micro-optical components, optical components, integrated circuits and optoelectronic semiconductor related components, industrial inspection, panel inspection, laser processing, etc. Compared with the non-destructive, high-precision and high-quality full-field three-dimensional composite surface imaging and measurement that is difficult to perform by contact industrial inspection, it shows the importance of the present invention in new types of technological applications and industrial development.

According to an aspect of the present invention, a method for measuring the three-dimensional composite surface profile of an object is provided, which includes the following steps: projecting an image onto a sample through at least one set of projection units; and then recording the image through an image access unit The reflected light of the sample; then, through a digital hologram reconstruction method, to reconstruct the reflected light of the specular surface of the sample and its surface three-dimensional profile information; after that, through a fringe projection analysis method, to reconstruct the diffuse of the sample The phase image of the surface and its surface three-dimensional contour information; finally, through an image bonding method, the three-dimensional images of the specular surface and the diffuse surface are image-aligned to reconstruct the complete three-dimensional image and contour information of the composite surface of the sample .

The above method further includes in the fringe projection analysis method, reconstructing the phase image of the diffuse surface of the sample and its surface three-dimensional profile information through digital hologram reconstruction of the reflected wavefront of the sample surface.

According to another aspect of the present invention, a method for measuring the three-dimensional composite surface profile of an object is provided, which includes the following steps: passing through a projection unit, so that the light wave without fringe information is incident on a sample; then, opening a switch (shutter), passing through An image access unit to record the interference image of the object light wave reflected from the sample and the reference light wave; then, through a digital hologram reconstruction method, the numerical reconstruction of the sample is performed to obtain the first three-dimensional image of the sample ; After that, through the projection unit, the fringe information light wave is incident on the sample; next, close the switch (shutter), and through the image access unit, to record the image of the deformed fringe reflected from the sample; then, through A fringe projection reconstruction method for performing numerical reconstruction of the sample to obtain a second 3D image of the sample; finally, image alignment of the first 3D image and the second 3D image through an image bonding method , to reconstruct the complete 3D image and contour information of the composite surface of the sample. The projection unit includes a projector, a spatial light modulator, an electric control light mirror, a liquid crystal microdisplay, a grating or a digital micromirror device.

According to another aspect of the present invention, a method for measuring the three-dimensional composite surface profile of an object is provided, which includes the following steps: passing through a projection unit, so that the fringe information light wave is incident on a sample; then, opening a switch (shutter), passing through a The image access unit is used to record the interference image of the object light wave with fringe information reflected from the sample and the reference light wave; then, the numerical reconstruction of the sample is carried out through a digital hologram reconstruction method, and the sample's image is obtained The first three-dimensional image; afterward, performing numerical reconstruction of the sample through a fringe projection reconstruction method to obtain a second three-dimensional image of the sample; finally, using an image bonding method to combine the first three-dimensional image with the sample Image alignment is performed on the second 3D image to reconstruct the complete 3D image and contour information of the composite surface of the sample.

According to one aspect of the present invention, wherein the digital hologram reconstruction method includes Fourier transform method, convolution method, angular spectrum method, Fresnel diffraction approximation method or deep learning reconstruction method; and the fringe projection analysis method includes phase shift method, Fourier transform method or deep learning reconstruction method.

These advantages and other advantages will enable readers to clearly understand the present invention from the description of the following preferred embodiments and the patent scope of the application.

100: projection unit

102, 514: full white image

104, 516: Stripe distribution image

106: Detection Beam

108: Light splitting element

110: imaging lens group

112, 522: samples

114: Deformed fringe image

116: Reference beam

118, 534: shutter

120: image access unit

202, 204, 206, 208, 210: steps

302, 304, 306, 308, 310, 312, 314: steps

402, 404, 406, 408, 410: steps

502: emit light source

504, 508, 536, 540: mirror

505: Optical beam expander

506, 530: Polarizer

510, 528, 538: beam splitter

512: projection unit

518, 520, 524, 526: lens

532: photodetector array

The following detailed description of the present invention and the schematic diagram of the embodiment should make the present invention more fully understood; however, it should be understood that this is only used as a reference for understanding the application of the present invention, rather than limiting the present invention to a specific implementation Among the examples.

The first figure shows a schematic diagram of an optical system for measuring the three-dimensional composite surface profile of an object according to an embodiment of the present invention;

The second figure shows a flowchart of a method for measuring the three-dimensional composite surface profile of an object according to an embodiment of the present invention;

The third figure shows a flowchart of a method for measuring the three-dimensional composite surface profile of an object according to another embodiment of the present invention;

The fourth figure shows a flow chart of a method for measuring the three-dimensional composite surface profile of an object according to another embodiment of the present invention;

Fig. 5 shows a schematic diagram of an optical system for measuring the three-dimensional composite surface profile of an object according to the present invention.

Herein, the present invention will be described in detail with respect to specific embodiments of the invention and its viewpoints. Such descriptions are for explaining the outline or step flow of the present invention, and are for the purpose of illustration rather than limiting the patent scope of the present invention. Therefore, except for the specific embodiments and preferred embodiments in the description, the present invention can also be widely implemented in other different embodiments.

The present invention discloses a device and method for the distribution of three-dimensional compound surface contours of an object method, which combines digital holography and fringe projection technology in a single optical measurement system to reconstruct the three-dimensional composite surface profile distribution of digital holography (Digital Holography: DH) and fringe projection (Fringe Projection: FP) images. method. It is pointed out in the embodiment that the present invention can respectively reconstruct the three-dimensional image distribution of the digital hologram and the fringe projection object with only one shot, so as to achieve an image with high-resolution imaging effect.

The device and method for the three-dimensional composite surface profile distribution of the object of the present invention involve the use of the following technologies or methods:

(i) Fringe projection technology: The diffuse surface sample is recorded and reconstructed in real time through the digital coherent light fringe projection technology to reconstruct the three-dimensional surface profile of the diffuse surface sample.

(ii) Digital holography: The mirrored surface sample is recorded and reconstructed in real time by digital holography to reconstruct the three-dimensional surface profile of the mirrored surface sample.

(iii) Composite surface synthesis: use image bonding technology to combine the 3D reconstruction images of the diffuse block obtained from coherent light fringe projection analysis and the mirror block obtained by digital holography to reconstruct the full-field composite 3D contour distribution information of surface objects.

(iv) One shot: Periodic fringes are generated through the optical modulation element and imaged on the surface of the object, so that the surface of the object contains fringe image information, and the complex wavefront information of the object is recorded through digital holography. At this time, the amplitude image information includes The image information of the object itself and the fringe image information, while the phase information only includes the image information of the object itself; and then reconstruct the amplitude image (including object and fringe image information) and phase (including object image information) distribution through holographic wavefront reconstruction; When it is a specular surface, the 3D image distribution of the object on the specular surface can be reconstructed through the phase image information; if it is a diffuse surface, the 3D image distribution of the object on the diffuse surface can be reconstructed by using the amplitude image information through coherent light fringe projection technology, and then Through the image bonding technology, it can completely reconstruct the three-dimensional image outline of the compound surface of the object.

The present invention proposes to use only one shot to obtain the complex wavefront information of the object through digital holography, and reconstruct the three-dimensional contour of the object on the mirror surface by using the phase and reconstruct the three-dimensional contour of the object on the diffuse surface by using the amplitude fringe projection technology. , and then reorganize the three-dimensional contours of the object on the mirror surface and the diffuse surface through the image alignment technology, so as to achieve the three-dimensional contour imaging and measurement of the composite surface object in the whole field.

The first figure shows one of the embodiments of the present invention, which is to measure the three-dimensional composite surface of the object Schematic diagram of the structure and flow of the outline. This structure includes an optical system to generate a detection beam 106 and a reference beam (Reference Beam) 116 . For example, the optical system includes an emitting light source, at least one spectroscopic element, a projection unit (wavefront manipulation element), at least one photodetector array (for example: charge-coupled device (CCD), complementary Image sensors such as metal oxide semiconductor (CMOS), photodetectors, several imaging lenses, shutters, and several mirrors. The emission light source includes but is not limited to a vertical resonant cavity surface-emitting laser (Vertical-Cavity Surface-Emitting Laser; VCSEL), semiconductor laser (Semiconductor laser), solid-state laser (Solid-state laser), gas laser (Gas laser), liquid laser (Dye laser), fiber laser ( Fiber laser) or light-emitting diode (LED). The light source form of the emitted light source includes line light source, plane light source or spherical light source. The light source characteristics of the emitted light source include coherent light source, low coherent light source or non-coherent light source. The optical system includes imaging lens Group 110 is used to collect the wavefront of the transmitted or reflected light of the sample 112. The optical path of this optical system includes: a laser light source (for example: a diode laser light source) generates a laser light with a central wavelength, the laser light source After the incident light is reflected by the surface mirror, it first passes through the beam expander to generate a beam expander, and then enters the light splitting element to output two beams respectively. After one of the beams passes through the projection unit (wavefront control element) 100, the intensity of the incident light is changed. Wavefront. The incident light wavefront produces beam turning after the light splitting of light-splitting element 108. Wherein, the position and quantity of light-splitting element can be decided according to projection unit (wave front manipulation element) 100.For an embodiment, projection unit (wave front control element) 100 decides. The front control element) 100 includes a projection element, a projector, a spatial light modulator (Spatial light modulator: SLM), an electrically controlled light mirror, a liquid crystal microdisplay, a grating or a digital micromirror device (Digital micromirror device: DMD), to change The wavefront of the incident light, and project the image of all white (no streaks) or the image of fringe distribution. Projection unit 100 can provide all white image 102 and fringe distribution image 104. The incident light of fringe distribution image 104 passes through imaging lens group 110 will be incident on the sample 112 at an incident angle to form a deformed fringe image 114. Then, the light field reflected by the sample 112 further passes through the imaging lens group 110, and then passes through the light splitting element 108 to form an image on the image access unit 120. The other beam is reflected by a mirror as the reference beam 116. The reflected beam and the reference beam 116 will form interference in the image access unit 120. The interference information is recorded in the image access unit 120 to obtain a digital holographic record. For example , the image access unit 120 includes a photodetector array or an image sensor. The shutter 118 is disposed at the position where the reference beam 116 travels.

By opening or closing the shutter 118 , the reference beam 116 can go forward or block the reference beam 116 .

The mirror is used to change the optical path of the laser light. The above-mentioned lens can be other elements capable of generating beam-expanding wavefronts (plane and spherical waves), or other elements capable of generating planar, spherical, and arbitrary curved wavefronts.

As shown in the second figure, it shows a flow chart of measuring the three-dimensional compound surface profile of an object according to an embodiment of the present invention. Firstly, step 202 is executed to project an image onto a sample through at least one set of projection units. In step 202, the projection unit 100 of the first image projects a completely white (no streak) image 102 or a streak distribution image 104, and projects it onto a sample 112 through the imaging lens group 110, wherein the sample 112 includes a specular surface and a diffuse shooting surface. Next, step 204 is executed to record the reflected light wavefront of the sample 112 through the image access unit. In step 204 , the light wave reflected by the sample 112 passes through the imaging lens group 110 , and is then split by the light splitting element 108 to form an image on the image access unit 120 . And through the image access unit, the wavefront of the reflected light of the sample 112 can be recorded. Then, step 206 is executed to reconstruct the wavefront of the reflected light of the mirror surface of the sample 112 and its surface three-dimensional profile information through the digital hologram reconstruction method. As an example, the digital hologram reconstruction method includes but not limited to Fourier transform method, convolution method, angular spectrum method, Fresnel diffraction approximation method or deep learning reconstruction method. Subsequently, step 208 is executed to reconstruct the phase image of the diffuse surface of the sample 112 and its surface three-dimensional profile information through the fringe projection analysis method. In step 208 , further included in the fringe projection analysis method, the phase image of the diffuse surface of the sample 112 and its surface three-dimensional profile information are reconstructed through the digital hologram reconstructed reflection wavefront of the sample surface. As an example, the fringe projection analysis method includes but not limited to phase shift method, Fourier transform method or deep learning reconstruction method. Finally, step 210 is executed to align the surface 3D images of the specular surface and the diffuse surface through the image bonding method, so as to reconstruct the complete 3D image and contour information of the composite surface of the object sample 112 . In one embodiment, the image bonding method includes image alignment technology.

As shown in the third figure, it shows a flow chart of measuring the three-dimensional composite surface profile of an object according to another embodiment of the present invention. In this embodiment, multiple photographs of the sample are taken, which are respectively recorded and reconstructed by digital holography and fringe projection. Firstly, in the recording and reconstruction of digital holography, step 302 is executed to inject all white (no fringe) information light waves to a sample through the projection unit. In step 302 , the projection unit 100 of the first figure projects a full white image 102 through the imaging lens set 110 to project onto a sample 112 , wherein the sample 112 includes a specular surface and a diffuse surface. in record digits In imaging, the all-white projected image is projected through a projection unit (such as a projector, a spatial light modulator), and at this time, the light wave with all-white information passes through one or more lenses, and is in the same way as the object sample. The line is incident on the sample 112 at an oblique angle. Next, step 304 is executed to open the shutter (switch) to record the interference image of the object light wave reflected from the sample and the reference light wave through the image access unit. In step 304, the shutter disposed at the traveling position of the reference beam is opened. The light wave reflected by the sample 112 will pass through the imaging lens group, and then be imaged on the image access unit through the light splitting of the light splitting element. Through the image access unit, the interference image of the object light wave reflected by the sample 112 and the reference light wave can be recorded. For example, the light wave information of the object reflected from the sample 112 passes through one or more lenses, and propagates to the plane where the image sensor is located. At the same time, the shutter at the position of the reference light is opened, so that the reference light is incident on the image sensor At this time, the object light and the reference light will interfere and generate interference fringes, and the interference image is recorded through the image sensor (this interference image is called a digital hologram). Then, step 306 is executed to perform numerical reconstruction of the sample through a digital hologram reconstruction method to obtain a first three-dimensional image (including amplitude, phase and height) of the sample. In step 306, the first three-dimensional image (digital hologram) is transmitted to the computer, and a digital hologram reconstruction algorithm is created (written) through the programming software to perform numerical reconstruction of the sample. As an example, the digital hologram reconstruction method includes but not limited to Fourier transform method, convolution method, angular spectrum method, Fresnel diffraction approximation method or deep learning reconstruction method. For example, the procedures established by the above-mentioned program software at least include, after digital full photo capture: Fourier transform, circle selection of first-order items, inverse Fourier transform, tilt/spherical correction, and acquisition of amplitude and phase images.

Subsequently, during the recording and reconstruction of the fringe projection technique, step 308 is executed to inject the fringe information light wave into a sample through the projection unit. In step 308, when recording the fringe projection technique, the sinusoidal fringe image will be generated through the program software, and projected through the projection unit (such as: projector, spatial light modulator), and the light wave with fringe information passes through After one or more lenses, it is incident on the sample 112 at an oblique angle with the normal of the sample 112 . Next, step 310 is executed to close the shutter and record the image of the deformed fringes reflected from the sample through the image access unit. In step 310, the deformed fringe information reflected from the object sample 112 passes through one or more lenses, and propagates to the plane where the image access unit is located. At this time, the shutter at the position of the reference light is closed, and the image transmitted The access unit records images of the deformed stripes. Then, step 312 is executed to perform numerical reconstruction of the sample through the fringe projection reconstruction method to obtain a second 3D image (including amplitude, phase and height) of the sample. In step 312, the second 3D image is transmitted to the computer, and a program software is used to create (write) a A texture projection reconstruction algorithm for numerical reconstruction of samples. As an example, fringe projection reconstruction (analysis) methods include but are not limited to phase shift methods, Fourier transform methods or deep learning reconstruction methods. For example, the procedure established by the above-mentioned program software at least includes, after the deformed fringes are captured, four-step reconstruction, amplitude-phase image, phase conversion to actual phase, and phase-to-height conversion to obtain the height image. Finally, in step 314 , the first 3D image and the second 3D image are image-aligned through an image bonding (fusion) method, so as to reconstruct a complete 3D image and contour information of the composite surface of the sample. In one embodiment, the image bonding method includes image alignment technology. For example, the program established by the above-mentioned image bonding (fusion) program software at least includes: calculating the surface height of the digital hologram image, fringe projection height image, and performing image fusion.

As shown in FIG. 4 , it shows a flow chart of measuring the three-dimensional composite surface profile of an object according to another embodiment of the present invention. In this example, a single shot of the sample is taken, which simultaneously records and reconstructs digital holography and fringe projection. Firstly, in the recording and reconstruction of digital holography, step 402 is executed to inject fringe information light waves into a sample through a projection unit. In step 402 , the fringe distribution image 104 of the projection unit 100 in the first figure is projected onto a sample 112 through the imaging lens group 110 , wherein the sample 112 includes a specular surface and a diffuse surface. When recording digital holography, the projected image with fringe distribution is projected through a projection unit (such as a projector, a spatial light modulator), and at this time, the light wave with fringe information passes through one or more lenses to communicate with the The normal line of the object sample is incident on the sample 112 at an oblique angle. Next, step 404 is executed to open the shutter (switch) and pass through the digital hologram access unit to record the interference image of the object light wave with fringe information reflected from the sample and the reference light wave. In step 404, the deformed fringe information with the sample reflected from the object sample passes through one or more lenses, and spreads to the plane where the image access unit is located, and at the same time opens the shutter arranged at the traveling position of the reference beam, so that The reference light is incident on the plane where the image access unit is located. At this time, the object light wave with fringe information and the reference light wave will interfere and generate interference fringes. The interference image is recorded through the image access unit (this interference image is called digital hologram). That is, through the image access unit, the interference image of the object light wave reflected by the sample 112 and the reference light wave can be recorded.

Next, step 406 is executed to perform numerical reconstruction of the sample through a digital hologram reconstruction method to obtain a first 3D image (including amplitude, phase and height) of the sample. In step 406, the first three-dimensional image (digital hologram) is transmitted to the computer, and a digital hologram reconstruction algorithm is established (written) through the programming software to perform numerical reconstruction of the sample. At this time, the amplitude image of the first three-dimensional image It will contain both object sample information and deformed fringe information. As an example, the digital hologram reconstruction method includes but not limited to Fourier transform method, convolution method, angular spectrum method, Fresnel diffraction approximation method or deep learning reconstruction method. Subsequently, step 408 is executed to perform numerical reconstruction of the sample through the fringe projection reconstruction method to obtain a second 3D image (including amplitude, phase and height) of the sample. In step 408, the amplitude image of the second 3D image is transmitted to the computer, and a fringe projection reconstruction algorithm is established (written) through the programming software for numerical reconstruction of the sample. As an example, fringe projection reconstruction (analysis) algorithms include but are not limited to phase shifting, Fourier transform or deep learning reconstruction. Finally, step 410 is executed to align the first 3D image and the second 3D image through an image bonding method, so as to reconstruct a complete 3D image and contour information of the composite surface of the sample. In one embodiment, the image bonding method includes image alignment technology.

The characteristics of the above samples: composite surface material (mirror surface, diffuse surface), high-level samples.

FIG. 5 shows a schematic diagram of an optical system for measuring the three-dimensional composite surface profile of an object according to an embodiment of the present invention. The optical system of this embodiment includes an emission light source 502, a beam expander (Beam expander; BE) 505, three beam splitters (Beam Splitter) 510, 528 and 538, a projection unit 512, and a photodetector array 532 (for example: Charge-coupled Device (CCD), Complementary Metal Oxide Semiconductor (CMOS) image sensor, Photodetector), four lenses (Lens) 518, 520, 524 and 526 , four mirrors (Mirror) 504 , 508 , 536 and 540 , two polarizers (Polarizer) 506 and 530 , and a shutter 534 . The emitting light source 502 includes vertical-cavity surface-emitting laser (Vertical-Cavity Surface-Emitting Laser; VCSEL), semiconductor laser (Semiconductor laser), solid-state laser (Solid-state laser), gas laser (Gas laser), Liquid laser (Dye laser), fiber laser (Fiber laser) or light emitting diode (LED). The light source form of the emitting light source 502 includes a linear light source, a plane light source or a spherical light source. The light source characteristics of the emitting light source 502 include a coherent light source, a low coherent light source or a non-coherent light source. The above four mirrors 504, 508, 536 and 540 are only used to change the optical path of the laser light.

In this embodiment, the emitting light source 502 adopts a diode-pumped solid-state laser (Diode-Pumped Solid-State Laser: DPSS Laser) with a wavelength of 532 nm (nanometer). The optical path of the optical system includes: a diode laser 502 light source generates a laser light with a central wavelength of 532nm, the laser After the incident light is reflected by the surface mirror 504, it first passes through the beam expander 505, expands the laser beam and collimates it into parallel light, so as to generate an expanded beam; then, the beam passes through the polarizer 506 to generate polarized light, and then passes through the Reflected by the surface mirror 508, the light beam is divided into two light beams by a beam splitter 510: object light (Object beam) and reference light (Reference beam); wherein the light beam of the object light passes through a projection unit (such as a digital micromirror device: DMD) A full white image 514 or a fringe distribution image 516 is projected.

In this optical system, the optical path of the object light in digital holography and fringe projection is the same, mainly through the digital micromirror device (DMD) 512 to adjust the amplitude, which provides, for example, a pixel size of 7.6×7.6μm ² and a number of pixels of 684× The images of 608 are respectively projected into different computer-generated holograms (CGH) for recording and reconstruction of digital holograms and fringe projections. After the light beam is reflected by the DMD, the light wave carries CGH information and passes through the imaging magnification system composed of the lens 518 (focal length f=100mm) and the lens 520 (focal length f=250mm), and enters the sample 522. The incident angle is, for example, 22.5 degrees, and in the same direction as the reflection angle of 22.5 degrees, then through the one-to-one imaging system composed of lens 524 (focal length f=200mm) and lens 526 (focal length f=200mm), through beam splitter 528 and polarizer 530 Imaging on the photodetector array 532; through this imaging system, the information with the wavefront of the object is imaged on the image sensor 532, for example, an image with a pixel size of 5.2×5.2μm ² and a pixel number of 1280×1024 .

In the above optical system, when multiple shots of the sample 522 are to be taken, operations are divided into digital holography and fringe projection. In the process of recording the digital hologram, through the DMD 512 to project the all-white CGH and open the shutter 534 located at the position of the reference light to let the reference light pass through, the reference light is reflected by the mirror 536, and the light path of the beam splitter 538 is pulled After being reflected by the beam splitter 528 , the object light interferes with the reference light and passes through the image sensor to record the interference fringe information. Afterwards, the interference fringe image information is transmitted to a computer, and then a three-dimensional image (including amplitude, phase, and height) of the sample 522 is reconstructed through a digital hologram reconstruction algorithm (eg, angle spectrum method). In addition, in the process of recording fringe projection, DMD 512 projects the sinusoidal fringe image generated through the program software, and closes the shutter 534 at the position of the reference light, records the deformed fringe image through the image sensor, and then composes the fringe through the program software A projection reconstruction algorithm (for example: Fourier transform method) is used to reconstruct and obtain a three-dimensional image (including amplitude, phase and height) of the sample 522 .

In the above optical system, when a single shot of the sample 522 is to be taken, the recording and reconstruction of digital holography and fringe projection will be performed simultaneously. At this time, the DMD 512 projects the sinusoidal fringe image generated by the program software, and opens the shutter 534 located at the position of the reference light to allow the reference light to pass through, then the object light containing the information of the deformed fringe will interfere with the reference light and pass through the image sensor The device is used to record the interference fringe information; then the interference fringe image information is transmitted to the computer, and the three-dimensional image (including amplitude, phase, and height) of the sample 522 is reconstructed through a digital hologram reconstruction algorithm (eg, angle spectrum method). Among them, the amplitude image will contain both the object sample 522 information and the deformation fringe information, and then the amplitude image will be passed through the fringe projection reconstruction algorithm (Fourier transform method) written by the programming software to perform numerical reconstruction of the sample, and finally reconstruct the sample 522 3D image (including amplitude, phase and height).

In summary, the features and advantages of the present invention include:

(1) The present invention proposes to use digital holography combined with fringe projection technology to measure and reconstruct composite surface objects, and proposes to use only one shot to obtain complex wavefront information of objects through digital holography.

(2) The present invention uses the phase to reconstruct the three-dimensional outline of the object on the mirror surface and uses the amplitude to reconstruct the three-dimensional outline of the object on the diffuse surface through fringe projection technology, and then uses the image alignment technology to reconstruct the three-dimensional outline of the object on the mirror surface and the diffuse surface Recombination is carried out to achieve 3D contour imaging and measurement of full-field composite surface objects.

(3) The method provided by the present invention can obtain the three-dimensional profile distribution of the surface of the composite object in real time through an optical non-destructive method, and can specifically present the three-dimensional surface profile of the object by a quantitative analysis method.

(4) The method provided by the present invention can simultaneously measure composite surface objects with specular surfaces and diffuse surfaces.

(5) In order to achieve large-area and high-fidelity measurement purposes, the digital hologram wavefront recording and reconstruction unit of the present invention combines wavefront recording and reconstruction to improve the equivalent of the photodetector array in the optical system resolution to achieve wide-field high-resolution imaging.

(6) As verified by the experimental results, the present invention can accurately achieve the purpose of measuring the image of composite surface objects with the high-fidelity image obtained by the above-mentioned digital hologram and fringe image wavefront recording and reconstruction method and device.

In addition to those described here, various improvements that can be achieved through the examples and implementations described in the present invention should be included in the scope of the present invention. Therefore, the schema and The examples are all used to illustrate rather than limit the present invention, and the scope of protection of the present invention should only be based on the scope of patent applications listed thereafter.

202: Step

204: step

206: Step

208: Step

210: step

Claims (10)

A method for measuring the three-dimensional composite surface profile of an object, comprising: Projecting at least one set of images onto a sample through at least one set of projection units; through an image access unit to record the reflected light of the sample; Reconstructing the reflected light wavefront of the specular surface of the sample and its surface three-dimensional profile information through a digital hologram; Reconstructing the phase image of the diffuse surface of the sample and its surface three-dimensional profile information through a fringe projection analysis; and Image alignment of the specular surface and the 3D image of the diffuse surface is carried out through image lamination, so as to reconstruct the complete 3D image and contour information of the composite surface of the sample. The method for measuring the three-dimensional composite surface profile of an object as described in claim 1 further includes, in the fringe projection analysis step, reconstructing the reflected wavefront of the specular surface of the sample through the digital hologram, and reconstructing the diffuse surface of the sample The phase image and its surface three-dimensional profile information. The method for measuring the three-dimensional composite surface profile of an object as described in Claim 1, wherein the digital hologram reconstruction method includes Fourier transform method, convolution method, angular spectrum method, Fresnel diffraction approximation method or deep learning reconstruction method . The method for measuring the three-dimensional composite surface profile of an object as described in Claim 1, wherein the fringe projection analysis method includes phase shift method, Fourier transform method or deep learning reconstruction method. A method for measuring the three-dimensional composite surface profile of an object, comprising: Through a projection unit, the fringe-free information light wave is incident on a sample; Turn on a switch to record the interference image of the object light wave reflected from the sample and the reference light wave through an image access unit; performing numerical reconstruction of the sample through a digital hologram reconstruction to obtain a first three-dimensional image of the sample; Through the projection unit, the fringe information light wave is incident on the sample; closing the switch, and recording the image of the deformed fringes reflected from the sample through the image access unit; obtaining a second 3D image of the sample by numerically reconstructing the sample through a fringe projection reconstruction; and The first three-dimensional image and the second three-dimensional image are image-aligned through an image lamination, so as to reconstruct the complete three-dimensional image and contour information of the composite surface of the sample. The method for measuring the three-dimensional composite surface profile of an object as described in Claim 5, wherein the projection unit includes a projector, a spatial light modulator, an electrically controlled optical mirror, a liquid crystal microdisplay, a grating or a digital micromirror device. The method for measuring the three-dimensional composite surface profile of an object as described in Claim 5, wherein the digital hologram reconstruction method includes Fourier transform method, convolution method, angular spectrum method, Fresnel diffraction approximation method or deep learning reconstruction method . The method for measuring the three-dimensional composite surface profile of an object as described in Claim 5, wherein the fringe projection analysis method includes phase shift method, Fourier transform method or deep learning reconstruction method. A method for measuring the three-dimensional composite surface profile of an object, comprising: Through a projection unit, the fringe information light wave is incident to a sample; Turn on a switch to record the interference image of the object light wave with fringe information reflected from the sample and the reference light wave through an image access unit; obtaining a first three-dimensional image of the sample by numerically reconstructing the sample through a digital hologram reconstruction; obtaining a second 3D image of the sample by numerically reconstructing the sample through a fringe projection reconstruction; and The first three-dimensional image and the second three-dimensional image are image-aligned through an image lamination, so as to reconstruct the complete three-dimensional image and contour information of the composite surface of the sample. The method for measuring the three-dimensional composite surface profile of an object as described in Claim 9, wherein the digital hologram is reconstructed Methods, including Fourier transform method, convolution method, angular spectrum method, Fresnel diffraction approximation method or deep learning reconstruction method; the fringe projection analysis method includes phase shift method, Fourier transform method or deep learning reconstruction method.

Images