阅读说明：本技术 基于3ccd或3cmos的动态三波长数字全息测量方法 (Dynamic three-wavelength digital holographic measurement method based on 3CCD or 3CMOS ) 是由 李凯 于 2020-06-02 设计创作，主要内容包括：本发明公开了一种基于3CCD或3CMOS的动态三波长数字全息测量方法,其特征在于,利用3CCD或3CMOS图像采集系统,对被测试件(S)表面进行动态三波长数字全息测量,在接收端通过3个CCD芯片或3个CMOS芯片组成一个图像采集系统,实现对3个波长全息图的同时采集,得到3个激光波长对应的激光全息图,进而得出被测试件(S)表面的三维形貌信息。本发明方法可实现同时采集三幅多波长全息图,从而实现高精度的动态测量,由于该方法显著的降低了多波长数字全息方法对环境振动和空气扰动的隔振性要求,从而能够更广泛的应用于更多的测量对象。(The invention discloses a dynamic three-wavelength digital holographic measurement method based on a 3CCD or a 3CMOS, which is characterized in that a 3CCD or 3CMOS image acquisition system is utilized to carry out dynamic three-wavelength digital holographic measurement on the surface of a tested piece (S), an image acquisition system is formed by 3CCD chips or 3CMOS chips at a receiving end, the 3 wavelength holograms are simultaneously acquired, laser holograms corresponding to 3 laser wavelengths are obtained, and then three-dimensional morphology information of the surface of the tested piece (S) is obtained. The method can realize the simultaneous collection of three multi-wavelength holograms, thereby realizing high-precision dynamic measurement, and can be widely applied to more measuring objects because the method obviously reduces the vibration isolation requirements of the multi-wavelength digital holography method on environmental vibration and air disturbance.)

1. A dynamic three-wavelength digital holographic measurement method based on 3CCD or 3CMOS is characterized in that a 3CCD or 3CMOS image acquisition system is utilized to carry out dynamic three-wavelength digital holographic measurement on the surface of a tested piece (S), and the dynamic three-wavelength digital holographic measurement method based on 3CCD or 3CMOS comprises the following steps:

a. using lasers of 3 wavelengths, the laser wavelengths being lambda respectively₁，λ₂，λ₃3 independent Mach-Zehnder (Mach-Zehnder) interference optical paths are formed, and laser with each wavelength corresponds to one Mach-Zehnder interference optical path; 3 interference holograms generated by the interference light paths are received by the photoelectric device at a receiving end by 3 CCDs or 3CMOS cameras;

b. wavelength of λ₁The first Laser beam emitted from Laser1 via Mach-Zehnder interference light path passes through a first pinhole filter (SF)₁) Beam expanding filtering and a first lens (L)₁) After collimation, it is passed through a first Polarizing Beam Splitter (PBS)₁) Is divided into two beams; wherein one of the sub-beams is used as a reference light and passes through a first reflector (M)₁) Reflecting and then injecting the reflected light into a target surface of a 3CCD chip or a 3CMOS chip; the other sub-beam is used as the detection object light via the second reflector (M)₂) After reflection, the laser is converged by a Converging Lens (CL) and irradiated on the surface of a tested piece (S), and the laser reflected by the surface of the tested piece passes through a fifth spectroscope (BS)₅) After reflection, the light is coherent with the corresponding reference lightSuperposed to form a wavelength lambda corresponding to the first laser beam₁The hologram of (3), received by a 3CCD chip or a 3CMOS chip;

wavelength of λ₂Through a second pinhole filter (SF)₂) Beam expanding filtering and a first lens (L)₂) After collimation, it is passed through a second Polarizing Beam Splitter (PBS)₂) Is divided into two beams; wherein one of the sub-beams passes through a third reflector (M)₃) And a third beam splitter (BF)₃) After reflection, the light enters a target surface of a 3CCD chip or a 3CMOS chip; the other beam is passed through a first beam splitter (BF)₁) And a second reflector (M)₂) After reflection, the laser is converged by a Converging Lens (CL) and irradiated on the surface of a tested piece (S), and the laser reflected by the surface of the tested piece passes through a fifth spectroscope (BS)₅) After reflection, the reflected light is coherently superposed with the corresponding reference light to form a wavelength lambda corresponding to the second laser beam₂The hologram of (3), received by a 3CCD chip or a 3CMOS chip;

wavelength of λ₃Through a third pinhole filter (SF)₃) Beam expanding filtering and a first lens (L)₃) After collimation, it is passed through a third Polarizing Beam Splitter (PBS)₃) Is divided into two beams; wherein one of the sub-beams passes through a fourth reflector (M)₄) After reflection, the light enters a target surface of a 3CCD chip or a 3CMOS chip; the other beam is split by a second beam splitter (BF)₂) And a second reflector (M)₂) After reflection, the laser is converged by a Converging Lens (CL) and irradiated on the surface of a tested piece (S), and the laser reflected by the surface of the tested piece passes through a fifth spectroscope (BS)₅) After reflection, the reflected light is coherently superposed with the corresponding reference light to form a wavelength lambda corresponding to the third laser beam₃The hologram of (3), received by a 3CCD chip or a 3CMOS chip;

c. each light path passes through a corresponding half-wave plate (lambda)₁/2，λ₂/2，λ₃/2) and corresponding Polarizing Beam Splitters (PBS)₁，PBS₂，PBS₃) The light intensity ratio between the reference light and the object light is adjusted by combining;

d. the 3CCD or 3CMOS image acquisition system consists of three dichroic prisms (A, B, C) and 3CCD chips (CCD1, CCD2 and CCD3) or three COMS chips (COMS1, COMS2 and COMS 3); said 3The CCD or 3CMOS image acquisition system can be based on the color separation film (F) plated on the color separation prism₁、F₂) The light with specific wavelength is reflected and transmitted, and the 3CCD chips or the 3 COMS chips are respectively used for collecting images formed by the light with three different wave bands;

e.3 wavelengths (λ)₁、λ₂、λ₃) After the laser enters a 3CCD or 3CMOS system, the first laser wavelength is lambda₁Through the first dichroic film (F)₁) The reflection and the total reflection of the first prism (A) and the air interface finally enter the CCD of the first light path acquisition device₁Chip or CMOS₁A chip;

the second laser wavelength is λ₂Is on the second dichroic film (F)₂) The second laser beam is reflected and then totally reflected at the interface of the second prism (B) and the air, a small gap is arranged between the first prism (A) and the second prism (B), and finally the second laser beam enters the CCD of the second optical path acquisition device₂Chip or CMOS₂A chip;

the third laser beam has a wavelength λ₃The light is not reflected by the color separation film and finally reaches the CCD of the third light path acquisition device₃Chip or CMOS₃A chip;

therefore, the simultaneous acquisition of the three wavelength holograms is realized;

f. the specific values of the three wavelengths of the three lasers are selected so that the wavelength (lambda) of the laser is excited by the first laser₁) And a third laser wavelength (λ)₃) The first equivalent wavelength (Λ) generated₁₃) And by a second laser wavelength (lambda)₂) And a third laser wavelength (λ)₃) The generated second equivalent wavelength (Λ)₂₃) Are smaller than the wavelength (lambda) of the first laser beam₁) And a second laser wavelength (λ)₂) Generated third equivalent wavelength (Λ)₁₂) Let the first equivalent wavelength (Λ)₁₃) And a second equivalent wavelength (Λ)₂₃) The noise corresponding to the two equivalent wavelengths will be less than the noise directly using the third equivalent wavelength (Λ)₁₂) Corresponding noise; then passes through the first equivalent wavelength (Λ)₁₃) A second equivalent wavelength (Λ)₂₃) The two equivalent wavelengths are subjected to layered phase unwrapping to obtain the correspondingThird equivalent wavelength (Λ)₁₂) A phase of (a);

therefore, an image acquisition system is formed by 3CCD chips or 3CMOS chips at a receiving end, 3 wavelength holograms are acquired simultaneously, laser holograms corresponding to 3 laser wavelengths are obtained, and then three-dimensional shape information of the surface of the tested piece (S) is obtained.

2. The 3CCD or 3CMOS based dynamic three wavelength digital holographic measurement method according to claim 1, characterized in that: for the first mirror (M) in the light path by adjustment₁) And a third spectroscope (BF)₃) Fourth beam splitter (BF)₄) And a fifth beam splitter (BF)₅) The included angle between the reference light and the object light can be controlled, so that the measuring light path meets the separable condition between the off-axis holographic reconstructed images.

3. The 3CCD or 3CMOS based dynamic three wavelength digital holographic measurement method according to claim 1, characterized in that: the light is split by corresponding beam splitters in each light path, including a first Beam Splitter (BS)₁) A second spectroscope (BS)₂) A third spectroscope (BS)₃) A fourth spectroscope (BS)₄) And a fifth Beam Splitter (BS)₅)；

The first laser beam is reflected by a first Polarizing Beam Splitter (PBS)₁) Is divided into two beams; wherein one of the sub-beams is used as a reference light and passes through a first reflector (M)₁) After reflection, the beam passes through a third spectroscope (BS)₃) A fourth spectroscope (BS)₄) And a fifth Beam Splitter (BS)₅) Splitting light and then injecting the light into a CCD or CMOS target surface; the other beam passes through a first Beam Splitter (BS)₁) A second spectroscope (BS)₂) After light splitting, the light passes through a second reflector (M)₂) After reflection, the light is converged by a Converging Lens (CL) and irradiates the surface of the tested piece (S);

the second laser beam is split by a second Polarizing Beam Splitter (PBS)₂) Is divided into two beams; wherein one of the sub-beams passes through a third reflector (M)₃) After reflection, the beam passes through a third spectroscope (BS)₃) A fourth spectroscope (BS)₄) And a fifth Beam Splitter (BS)₅) Splitting light and emitting the light to a CCD or CMOS target surface; the other beam passes through a first Beam Splitter (BS)₁) A second spectroscope (BS)₂) After light splitting, the light passes through a second reflector (M)₂) After reflection, the light is converged by a Converging Lens (CL) and irradiates the surface of the tested piece (S);

the third laser beam is reflected by a third Polarizing Beam Splitter (PBS)₃) Is divided into two beams; wherein one of the sub-beams passes through a fourth reflector (M)₄) After reflection, the light passes through a fourth spectroscope (BS)₄) And a fifth Beam Splitter (BS)₅) Splitting light and emitting the light to a CCD or CMOS target surface; second Beam Splitter (BS) for another sub-beam₂) After light splitting, the light passes through a second reflector (M)₂) After reflection, the light is converged by a Converging Lens (CL) and irradiates the surface of the tested piece (S).

4. The 3CCD or 3CMOS based dynamic three-wavelength digital holographic measurement method according to claim 3, wherein: by adjusting a first mirror (M) in the light path₁) A third spectroscope (BS)₃) And a fourth spectroscope (BS)₄) And a fifth Beam Splitter (BS)₅) The included angle between the reference light and the object light can be controlled, so that the measuring light path meets the separable condition between off-axis holographic reconstructed images.

Technical Field

The invention relates to a three-wavelength dynamic digital holographic measurement method based on a 3CCD or a 3CMOS, and belongs to the technical field of photoelectric detection.

Background

Digital holography is a novel imaging technology developed by combining the modern digital image technology on the basis of the traditional optical holographic technology. Unlike traditional optical holographic method, it uses CCD (Charge Coupled Device), CMOS (Complementary Metal Oxide Semiconductor) and other photoelectric devices to record hologram and store it in computer, reproduces the hologram by computer numerical simulation optical diffraction process, and directly displays and outputs the result, realizing the digitization of the whole holographic process from recording to reproduction. Compared with the traditional optical holography, the digital holography has the advantages of high imaging speed, capability of quantitative measurement and the like.

The phase obtained due to holographic reconstruction is the envelopePhase, which limits the measurement range of the measurement method. Although the envelope phase can be unwrapped, they mostly sacrifice computational efficiency, and more importantly, for those structural devices with deep trench sidewalls, the phase unwrapping method is not processable. To address this challenge, researchers have introduced multi-wavelength methods into digital holographic measurement techniques in recent years. As shown in fig. 1, fig. 1 is a basic principle of the multi-wavelength method. (a) Two rows of waves of close wavelength, each wavelength being lambda₁And λ₂. (b) The superposition of two trains of waves produces a beat effect with an equivalent wavelength of Λ₁₂. When two wavelengths (lambda) close to each other are used₁And λ₂) When the measurement is carried out, a beat effect is generated, and the beat has a larger equivalent wavelength lambda₁₂＝λ₁λ₂/|λ₁-λ₂If the equivalent wavelength is larger than the thickness of the measured sample, the phase distribution corresponding to the measured sample is [0,2 pi ]]Therefore, phase solution enveloping is not needed, and the problem of range limitation caused by enveloping phase is solved. However, the multi-wavelength method amplifies noise while expanding the measurement range, and thus reduces the measurement accuracy. In addition, the currently used multi-wavelength methods collect holograms of all wavelengths by using a camera, which results in that the holograms of all wavelengths are not collected simultaneously, and for measurement, the measured object is required to be kept still during the collection of the holograms of all wavelengths, so that the method cannot realize dynamic measurement, thereby greatly limiting the application range and the measured object of the method.

Disclosure of Invention

In order to solve the problems in the prior art, the invention aims to overcome the defect that the existing multi-wavelength digital holographic method cannot realize high-precision dynamic measurement, and provides a dynamic three-wavelength digital holographic measurement method based on 3CCD or 3CMOS, which can realize the simultaneous acquisition of three multi-wavelength holograms so as to realize high-precision dynamic measurement.

In order to achieve the purpose of the invention, the invention adopts the following technical scheme:

a dynamic three-wavelength digital holographic measurement method based on 3CCD or 3CMOS utilizes a 3CCD or 3CMOS image acquisition system to perform dynamic three-wavelength digital holographic measurement on the surface of a tested piece, and the dynamic three-wavelength digital holographic measurement method based on 3CCD or 3CMOS comprises the following steps:

a. using lasers of 3 wavelengths, the laser wavelengths being lambda respectively₁，λ₂，λ₃3 independent Mach-Zehnder interference optical paths are formed, and laser with each wavelength corresponds to one Mach-Zehnder interference optical path; 3 interference holograms generated by the interference light paths are received by the photoelectric device at a receiving end by 3 CCDs or 3CMOS cameras;

b. wavelength of λ₁The Mach-Zehnder interference light path sends out a first beam of Laser from a Laser1, and the first beam of Laser is expanded and filtered by a first pinhole filter, collimated by a first lens and then divided into two beams by a first polarization beam splitter; one beam of the sub-beams is reflected by a first reflector as reference light and then is incident into a target surface of a 3CCD chip or a target surface of a 3CMOS chip; the other beam of the sub-beams is used as a detection object, reflected by the second reflecting mirror, converged by the converging lens and irradiated on the surface of the tested piece, and the laser reflected by the surface of the tested piece is coherently superposed with the corresponding reference light after being reflected by the fifth reflecting mirror to form a wavelength lambda corresponding to the first beam of the laser₁The hologram of (3), received by a 3CCD chip or a 3CMOS chip;

wavelength of λ₂The second beam of laser is expanded and filtered by a second pinhole filter and collimated by a first lens, and then is divided into two beams by a second polarization spectroscope; one beam of the sub-beams is reflected by the third reflector and the third beam splitter and then enters the target surface of the 3CCD chip or the 3CMOS chip; the other beam is reflected by the first beam splitter and the second reflector, converged by the Converging Lens (CL) and irradiated on the surface of the tested piece, and the laser reflected by the surface of the tested piece is coherently superposed with the corresponding reference light after being reflected by the fifth beam splitter to form the wavelength lambda corresponding to the second beam laser₂The hologram of (3), received by a 3CCD chip or a 3CMOS chip;

wavelength of λ₃The third beam of laser is expanded and filtered by a third pinhole filter, collimated by a first lens and then divided into two beams by a third polarization spectroscope; one beam of the split beams is reflected by a fourth reflector and then is emitted to a target surface of a 3CCD chip or a 3CMOS chip; the other beam is reflected by the second beam splitter and the second reflector, converged by the converging lens and irradiated on the surface of the tested piece, and the laser reflected by the surface of the tested piece is reflected by the fifth beam splitter and then coherently superposed with the corresponding reference light to form a third beam of laser with the wavelength lambda₃The hologram of (3), received by a 3CCD chip or a 3CMOS chip;

c. each light path is used by combining a corresponding half-wave plate and a corresponding polarization spectroscope to adjust the light intensity ratio between the reference light and the object light;

d. the 3CCD or 3CMOS image acquisition system consists of three color separation prisms and 3CCD chips or three COMS chips; the 3CCD or 3CMOS image acquisition system can reflect and transmit light with specific wavelength according to a color separation film plated on the color separation prism, and the 3CCD chips or the 3 COMS chips are respectively used for acquiring images formed by the light with three different wave bands;

e.3 laser beams with different wavelengths enter a 3CCD or 3CMOS system, and the first laser beam has a wavelength of lambda₁The light is reflected by the first dichroic film and the first prism and is totally reflected by the air interface, and finally enters the CCD of the first light path acquisition device₁Chip or CMOS₁A chip;

the second laser wavelength is λ₂The second beam of laser light is reflected at the second dichroic film, then is totally reflected at the interface of the second prism and the air, a tiny gap is formed between the first prism and the second prism, and finally the second beam of laser light enters the CCD of the second light path acquisition device₂Chip or CMOS₂A chip;

the third laser beam has a wavelength λ₃The light is not reflected by the color separation film and finally reaches the CCD of the third light path acquisition device₃Chip or CMOS₃A chip;

therefore, the simultaneous acquisition of the three wavelength holograms is realized;

f. selecting specific values of three wavelengths of the three beams of laser light, so that a first equivalent wavelength generated by a first laser wavelength and a third laser wavelength and a second equivalent wavelength generated by a second laser wavelength and the third laser wavelength are both smaller than the third equivalent wavelength generated by the first laser wavelength and the second laser wavelength, and the noise corresponding to the two equivalent wavelengths of the first equivalent wavelength and the second equivalent wavelength is smaller than the noise corresponding to the third equivalent wavelength which is directly used; then, carrying out layered phase unwrapping through the first equivalent wavelength and the second equivalent wavelength to obtain a phase corresponding to a third equivalent wavelength;

therefore, an image acquisition system is formed by 3CCD chips or 3CMOS chips at a receiving end, 3 wavelength holograms are acquired simultaneously, laser holograms corresponding to 3 laser wavelengths are obtained, and then three-dimensional shape information of the surface of the tested piece is obtained.

Preferably, for the first mirror (M) in the path of the light by adjustment₁) And a third spectroscope (BF)₃) Fourth beam splitter (BF)₄) And a fifth beam splitter (BF)₅) The included angle between the reference light and the object light can be controlled, so that the measuring light path meets the separable condition between the off-axis holographic reconstructed images.

Preferably, each light path is split by a corresponding beam splitter, and the beam splitter comprises a first beam splitter, a second beam splitter, a third beam splitter, a fourth beam splitter and a fifth beam splitter;

the first beam of laser is divided into two beams by the first polarization beam splitter; one beam of the split beams is used as reference light, is reflected by the first reflecting mirror, then is split by the third beam splitter, the fourth beam splitter and the fifth beam splitter in sequence, and then is emitted to a CCD (charge coupled device) or CMOS (complementary metal oxide semiconductor) target surface; the other beam split is split by the first beam splitter and the second beam splitter in sequence, reflected by the second reflecting mirror, converged by the converging lens and irradiated on the surface of the tested piece;

the second beam of laser is divided into two beams by a second polarization beam splitter; one beam of the split beams is reflected by a third reflector, then is split by a third spectroscope, a fourth spectroscope and a fifth spectroscope in sequence and is incident to a CCD (charge coupled device) or CMOS (complementary metal oxide semiconductor) target surface; the other beam split is split by the first beam splitter and the second beam splitter in sequence, reflected by the second reflecting mirror, converged by the converging lens and irradiated on the surface of the tested piece;

the third beam of laser is divided into two beams by a third polarization beam splitter; one beam of the split beams is reflected by a fourth reflector, then is split by a fourth spectroscope and a fifth spectroscope in sequence and is incident to a CCD (charge coupled device) or CMOS (complementary metal oxide semiconductor) target surface; and after the other beam is split by the second beam splitter, the other beam is reflected by the second reflector, converged by the converging lens and irradiated on the surface of the tested piece.

Preferably, the first reflector, the third beam splitter, the fourth beam splitter and the fifth beam splitter in the optical path are adjusted to control the included angle between the reference light and the object light, so that the measuring optical path meets the separable condition between the off-axis holographic reconstructed images.

Compared with the prior art, the invention has the following obvious and prominent substantive characteristics and remarkable advantages:

1. the method adopts laser with three wavelengths, realizes a multi-wavelength digital holographic measuring optical path with three wavelengths through three independent Mach-Zehnder (Mach-Zehnder) interference optical paths, and realizes simultaneous acquisition of three wavelength holograms by forming an image acquisition system at a receiving end through three CCD (charge coupled device) or three CMOS (complementary metal oxide semiconductor) chips;

2. the method adopts the laser with three wavelengths to carry out measurement, improves the measurement range and simultaneously keeps good signal to noise ratio. In addition, the laser holograms corresponding to the three laser wavelengths can be simultaneously acquired, so that the method can realize dynamic measurement, thereby remarkably reducing the harsh requirements of a digital holographic method on isolation of environmental vibration and air disturbance, and being capable of being applied to wider fields and wider objects;

3. the method is simple and easy to implement, low in cost and suitable for popularization and application.

Drawings

Fig. 1 is a basic principle of a multi-wavelength method of the prior art.

FIG. 2 is a three-wavelength dynamic digital holographic microscopic measurement optical path of the present invention.

Fig. 3 is a 3CCD or 3CMOS image acquisition system of the present invention.

Detailed Description

The above-described scheme is further illustrated below with reference to specific embodiments, which are detailed below: