A digital holographic 3D reconstruction system and method based on a single-cavity dual-optical comb

Abstract

This invention discloses a digital holographic 3D reconstruction system and method based on a single-cavity dual-optical comb, belonging to the field of digital holographic 3D measurement technology. The invention includes: a single-cavity dual-optical comb, a coarse wavelength division multiplexer, a first fiber amplifier, a second fiber amplifier, a first fiber filter, a second fiber filter, a first fiber beam expander, a concave mirror, a second fiber beam expander, a beam splitter, an image sensor, and a computer. The single-cavity dual-optical comb emits two pulses, which are split, amplified, and filtered. The measurement light and the reference light produce interference fringes, forming a hologram. This invention uses a single-cavity dual-optical comb as a light source to achieve the separation of the zero-order image, twin image, and target re-phenomenon in coaxial holography, improving the quality of holographic imaging and facilitating engineering implementation. Based on multi-wavelength heterodyne technology, combined with the wide spectral bandwidth and high temporal coherence of the optical comb, this invention suppresses the influence of noise, enabling the measurement of large-size objects and expanding the application scenarios of digital holography.

Description

Technical Field

[0001] This invention relates to a digital holographic three-dimensional reconstruction system and method based on a single-cavity dual-optical comb, belonging to the field of digital holographic three-dimensional measurement technology. Background Technology

[0002] Digital holography is an optical interferometric measurement technique that was developed based on traditional optical holography and with the advancement of computer technology and optoelectronic imaging technology. It realizes the amplitude and phase distribution of object light waves. Digital holography includes two steps: holographic interferometric recording and holographic reconstruction. Holographic interferometric recording uses an image sensor to record a hologram of the interference between the object light and the reference light. Holographic reconstruction is to reconstruct the light wave through computer simulation to obtain the amplitude and phase information of the target object and realize the reconstruction of the field of the target object.

[0003] Coaxial digital holography requires a light source with low coherence and a recording device with low resolution. It has the advantages of simple optical system, low background noise and high measurement accuracy. However, when recording, the object light wave and the reference light wave propagate coaxially. In the reconstructed light wave field, the reconstructed object light wave, the zero-order term and the conjugate light wave coexist and overlap in space, which are difficult to separate. In addition, twin noise will appear, which limits the application of coaxial digital holography. Summary of the Invention

[0004] The purpose of this invention is to provide a digital holographic three-dimensional reconstruction system and method based on a single-cavity dual-optical comb. The system uses a single-cavity dual-optical comb as a light source to separate the zero-order image, twin image, and target re-phenomenon in coaxial holography, thereby improving the quality of holographic imaging. Based on multi-wavelength heterodyne technology, combined with the wide spectral bandwidth and high temporal coherence of the optical comb, the system suppresses the influence of noise and enables the measurement of large-size objects.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] The present invention provides a digital holographic three-dimensional reconstruction system based on a single-cavity dual-optical comb, comprising: a single-cavity dual-optical comb, a coarse wavelength division multiplexer, a first fiber amplifier, a second fiber amplifier, a first fiber filter, a second fiber filter, a first fiber beam expander, a concave mirror, a second fiber beam expander, a beam splitter, an image sensor, and a computer.

[0007] The single-cavity dual optical comb is used to emit a highly stable pulse beam, which contains two pulsed lasers with a repetition rate difference and different center wavelengths.

[0008] As a preferred option, the single-cavity dual optical comb operates in the near-infrared band;

[0009] The coarse wavelength division multiplexer splits the pulse beam emitted by the single-cavity dual optical comb into two beams based on the different center wavelengths of the two pulsed lasers: one beam is used as a reference beam and the other is used as a measurement beam.

[0010] Preferably, the coarse wavelength division multiplexer operates in the near-infrared band;

[0011] The first fiber amplifier and the second fiber amplifier respectively amplify the pulse energy of the reference light and reconstruct the pulse spectrum of the measurement light;

[0012] Preferably, the first fiber amplifier and the second fiber amplifier are erbium-doped fiber amplifiers or ytterbium-doped fiber amplifiers;

[0013] The first fiber filter and the second fiber filter respectively filter the reference light and the measurement light after they have been amplified by the first fiber amplifier and the second fiber amplifier, so that the spectra of the reference light and the measurement light are consistent.

[0014] Preferably, the first fiber optic filter and the second fiber optic filter are broadband filters that operate in the near-infrared band.

[0015] The first fiber optic beam expander amplifies the measurement light that has passed through the first fiber optic filter and illuminates the object under test.

[0016] Preferably, the first fiber optic beam expander is a zoom fiber optic beam expander;

[0017] The concave mirror collects the measurement light reflected by the object under test, compresses the beam divergence angle, and emits it to the beam splitter.

[0018] Preferably, the working surface of the concave reflector is plated with gold or silver.

[0019] The second fiber beam expander amplifies the reference light that has passed through the second fiber filter and transmits it to the beam splitter;

[0020] Preferably, the second fiber beam expander is a zoom fiber beam expander;

[0021] The beam splitter combines the measurement light emitted by the concave mirror and the reference light emitted by the second fiber beam expander, causing interference between the measurement light and the reference light.

[0022] Preferably, the beam splitter operates in the near-infrared band;

[0023] The image sensor is used to record interference fringes generated by the interference of reference light and measurement light, and to discretize and digitize the interference fringes to form a digital hologram.

[0024] Preferably, the image sensor is a charge-coupled device or a complementary metal oxide;

[0025] The computer is used to perform noise reduction processing on digital holograms, numerically simulate the diffraction process, reproduce the intensity and phase information of the measured light, and realize three-dimensional reconstruction of the shape of the object under test.

[0026] Preferably, a multi-wavelength phase unwinding algorithm is used to reproduce the intensity and phase information of the measured light;

[0027] The working method of the digital holographic three-dimensional reconstruction system based on a single-cavity dual-optical comb according to the present invention is as follows:

[0028] The single-cavity dual-optical comb emits a highly stable pulse beam containing two pulsed lasers with different repetition rates and center wavelengths. The pulse beam is fed through an optical fiber into a coarse wavelength division multiplexer (CWDM), which splits it into two beams: one as a reference beam and the other as a measurement beam. The measurement beam is amplified by the first fiber amplifier, filtered by the first fiber filter, and then enters the first fiber beam expander. The expanded measurement beam illuminates the surface of the object under test. A concave reflector collects the reflected measurement beam and compresses the beam divergence angle before sending it to the beam splitter. The measurement beam entering the beam splitter carries the measurement target... The three-dimensional information of the object's surface morphology is obtained. The reference light is amplified by the second fiber amplifier and filtered by the second fiber filter. The reference light spectrum after passing through the first fiber filter and the second fiber filter is consistent with the measurement light. The filtered reference light enters the second fiber beam expander and is emitted to the beam splitter. The measurement light and the reference light are combined at the beam splitter and interfere to produce interference fringes. The image sensor records the interference fringes and forms a discrete and digitized hologram. The computer performs noise reduction processing on the digital hologram, numerically simulates the diffraction process, and reproduces the intensity and phase information of the measurement light to realize the three-dimensional reconstruction of the object's morphology.

[0029] Beneficial effects:

[0030] 1. The present invention provides a digital holographic three-dimensional reconstruction system based on a single-cavity dual-optical comb, which uses a single-cavity dual-optical comb as a light source and does not require phase-shifting devices. It realizes the separation of the zero-order image, twin image and target re-phenomenon in coaxial holography, which is convenient for engineering implementation.

[0031] 2. The present invention provides a digital holographic three-dimensional reconstruction system and method based on a single-cavity dual optical comb. Based on multi-wavelength heterodyne technology, and combined with the advantages of wide spectral bandwidth and high temporal coherence of the optical comb, it can suppress the influence of noise, realize the measurement of large-size objects, and expand the application scenarios of digital holography. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of a digital holographic three-dimensional reconstruction system based on a single-cavity dual-optical comb according to the present invention;

[0033] Among them, 1-single-cavity dual-optical comb, 2-coarse wavelength division multiplexer, 3-first fiber amplifier, 4-second fiber amplifier, 5-first fiber filter, 6-second fiber filter, 7-first fiber beam expander, 8-concave mirror, 9-second fiber beam expander, 10-beam splitter, 11-target under test, 12-image sensor, 13-computer. Detailed Implementation

[0034] To better illustrate the purpose and advantages of the present invention, the invention will be further described below in conjunction with the accompanying drawings and examples.

[0035] Example 1:

[0036] The embodiment applies a digital holographic three-dimensional reconstruction system and method based on a single-cavity dual-optical comb according to the present invention to realize the three-dimensional reconstruction of the morphology of the target under test.

[0037] like Figure 1 As shown, a digital holographic three-dimensional reconstruction system based on a single-cavity dual-optical comb includes: a single-cavity dual-optical comb 1, a coarse wavelength division multiplexer 2, a first fiber amplifier 3, a second fiber amplifier 4, a first fiber filter 5, a second fiber filter 6, a first fiber beam expander 7, a concave reflector 8, a second fiber beam expander 9, a beam splitter 10, an image sensor 12, and a computer 13.

[0038] A single-cavity dual-optical comb 1 is used to emit a highly stable pulse beam, which contains two pulsed lasers with different repetition rates and center wavelengths. A coarse wavelength division multiplexer 2 splits the pulse beam emitted by the single-cavity dual-optical comb 1 into two beams based on the different center wavelengths of the two pulsed lasers: one beam serves as a reference beam, and the other as a measurement beam. A first fiber amplifier 3 and a second fiber amplifier 4 amplify the pulse energy and reconstruct the pulse spectrum of the reference beam and the measurement beam, respectively. A first fiber filter 5 and a second fiber filter 6 filter the amplified reference beam and measurement beam, respectively, to ensure that their spectra are consistent. A first fiber beam expander 7 expands the measurement beam after passing through the first fiber filter 5. The beam is expanded and illuminated onto the object under test 11; the concave reflector 8 collects the measurement light reflected by the object under test 11, compresses the beam divergence angle, and emits it to the beam splitter 10; the second fiber beam expander 9 expands the reference light that has passed through the second fiber filter 6 and emits it to the beam splitter 10; the beam splitter 10 combines the measurement light emitted by the concave reflector 8 and the reference light emitted by the second fiber beam expander 9, causing the measurement light and the reference light to interfere; the image sensor 12 is used to record the interference fringes generated by the interference between the reference light and the measurement light, and to discretize and digitize the interference fringes to form a digital hologram; the computer 13 is used to perform noise reduction processing on the digital hologram, numerically simulate the diffraction process, reproduce the intensity and phase information of the measurement light, and realize the three-dimensional reconstruction of the shape of the object under test 11.

[0039] In this embodiment, the single-cavity dual-optical comb 1, the coarse wavelength division multiplexer 2, the first fiber filter 5, the second fiber filter 6, and the beam splitter 10 operate in the near-infrared band; the first fiber filter 5 and the second fiber filter 6 are broadband filters; the first fiber amplifier 3 and the second fiber amplifier 4 are erbium-doped fiber amplified lasers; the first fiber beam expander 7 and the second fiber beam expander 9 are zoom fiber beam expanders; the working surface of the concave reflector 8 is gold-plated; and the image sensor 12 is a charge-coupled device (CCD).

[0040] In this embodiment, a multi-wavelength phase unwrapping algorithm is used to reproduce the intensity and phase information of the measured light;

[0041] This embodiment applies a digital holographic 3D reconstruction system based on a single-cavity dual-optical comb, as described in this invention, to achieve 3D reconstruction of the shape of a target under test. The working method is as follows: The single-cavity dual-optical comb 1 emits a highly stable pulse beam, which contains two pulsed lasers with different repetition rates and center wavelengths. The pulse beam is fed into a coarse wavelength division multiplexer 2 via an optical fiber. The coarse wavelength division multiplexer 2 splits the pulse beam into two beams: one as a reference beam and the other as a measurement beam. The measurement beam is amplified by a first fiber amplifier 3, filtered by a first fiber filter 5, and then enters a first fiber beam expander 7. The expanded measurement beam illuminates the surface of the target object 11. A concave reflector 8 collects the measurement beam reflected by the target object 11 and compresses the beam divergence angle. The measurement light entering the beam splitter 10 carries three-dimensional information about the surface morphology of the object under test 11. The reference light is amplified by the second fiber amplifier 4 and filtered by the second fiber filter 6. The reference light and the measurement light have the same spectrum after passing through the first fiber filter 5 and the second fiber filter 6, respectively. The filtered reference light enters the second fiber beam expander 9 and is emitted to the beam splitter 10 after beam expansion. The measurement light and the reference light are combined at the beam splitter 10 and interfere to produce interference fringes. The image sensor 12 records the interference fringes and forms a discrete and digital hologram. The computer 13 performs noise reduction processing on the digital hologram, numerically simulates the diffraction process, and reproduces the intensity and phase information of the measurement light to realize the three-dimensional reconstruction of the morphology of the object under test 11.

[0042] The above detailed description further illustrates the purpose, technical solution, and beneficial effects of the invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A digital holographic three-dimensional reconstruction system based on a single-cavity dual-optical comb, characterized in that: include: The single-cavity dual optical comb (1), coarse wavelength division multiplexer (2), first fiber amplifier (3), second fiber amplifier (4), first fiber filter (5), second fiber filter (6), first fiber beam expander (7), concave mirror (8), second fiber beam expander (9), beam splitter (10), image sensor (12), and computer (13). A single-cavity dual-optical comb (1) is used to emit a highly stable pulse beam, which contains two pulsed lasers with different repetition rates and different center wavelengths; The coarse wavelength division multiplexer (2) divides the pulse beam emitted by the single cavity dual optical comb (1) into two beams based on the different center wavelengths of the two pulsed lasers: one beam is used as a reference beam and the other beam is used as a measurement beam. The first fiber amplifier (3) and the second fiber amplifier (4) respectively amplify the pulse energy and reconstruct the pulse spectrum of the reference light and the measurement light; The first fiber filter (5) and the second fiber filter (6) respectively filter the reference light and the measurement light after being amplified by the first fiber amplifier (3) and the second fiber amplifier (4) to make the spectra of the reference light and the measurement light consistent. The first fiber beam expander (7) expands the measurement light that has passed through the first fiber filter (5) and illuminates the object to be measured. The concave mirror (8) collects the measurement light reflected by the object to be measured, compresses the beam divergence angle, and emits it to the beam splitter (10); The second fiber beam expander (9) expands the reference light that has passed through the second fiber filter (6) and transmits it to the beam splitter (10); The beam splitter (10) combines the measurement light emitted by the concave mirror (8) and the reference light emitted by the second fiber beam expander (9) to cause interference between the measurement light and the reference light. The image sensor (12) is used to record the interference fringes generated by the interference of the reference light and the measurement light, and to discretize and digitize the interference fringes to form a digital hologram; The computer (13) is used to denoise the digital hologram, numerically simulate the diffraction process, reproduce the intensity and phase information of the measured light, and realize the three-dimensional reconstruction of the shape of the object under test.

2. The digital holographic three-dimensional reconstruction system based on a single-cavity dual-optical comb as described in claim 1, characterized in that: The working method is as follows: a single-cavity dual optical comb (1) emits a highly stable pulse beam, which contains two pulse lasers with different repetition rates and center wavelengths; the pulse beam is sent into a coarse wavelength division multiplexer (2) through an optical fiber, and the coarse wavelength division multiplexer (2) divides the pulse beam into two beams: one beam is used as a reference beam and the other beam is used as a measurement beam; the measurement beam is amplified by a first optical fiber amplifier (3) and filtered by a first optical fiber filter (5); the filtered measurement beam enters a first optical fiber beam expander (7); the expanded measurement beam illuminates the surface of the object to be measured; a concave reflector (8) collects the measurement beam reflected by the object to be measured and compresses the beam divergence angle, and sends it into a beam splitter (10); the measurement beam entering the beam splitter (10) carries three-dimensional information of the surface morphology of the object to be measured. The reference light is amplified by the second fiber amplifier (4) and filtered by the second fiber filter (6). After passing through the first fiber filter (5) and the second fiber filter (6), the reference light has the same spectrum as the measurement light. The filtered reference light enters the second fiber beam expander (9) and is emitted to the beam splitter (10) after beam expansion. The measurement light and the reference light are combined at the beam splitter (10) and interfere to produce interference fringes. The image sensor (12) records the interference fringes and forms a discrete and digital hologram. The computer (13) performs noise reduction processing on the digital hologram, numerically simulates the diffraction process, reproduces the intensity and phase information of the measurement light, and realizes the three-dimensional reconstruction of the shape of the object under test.

3. The digital holographic three-dimensional reconstruction system based on a single-cavity dual-optical comb as described in claim 1, characterized in that: The single-cavity dual optical comb (1), coarse wavelength division multiplexer (2), first fiber filter (5), second fiber filter (6) and beam splitter (10) operate in the near-infrared band.

4. The digital holographic three-dimensional reconstruction system based on a single-cavity dual-optical comb as described in claim 1, characterized in that: The first fiber optic filter (5) and the second fiber optic filter (6) are broadband filters.

5. The digital holographic three-dimensional reconstruction system based on a single-cavity dual-optical comb as described in claim 1, characterized in that: The first fiber amplifier (3) and the second fiber amplifier (4) are erbium-doped fiber amplifiers or ytterbium-doped fiber amplifiers.

6. The digital holographic three-dimensional reconstruction system based on a single-cavity dual-optical comb as described in claim 1, characterized in that: The first fiber optic beam expander (7) and the second fiber optic beam expander (9) are zoom fiber optic beam expanders.

7. The digital holographic three-dimensional reconstruction system based on a single-cavity dual-optical comb as described in claim 1, characterized in that: The working surface of the concave reflector (8) is plated with gold or silver.

8. The digital holographic three-dimensional reconstruction system based on a single-cavity dual-optical comb as described in claim 1, characterized in that: The image sensor (12) is a charge-coupled device or a complementary metal oxide.

9. The digital holographic three-dimensional reconstruction system based on a single-cavity dual-optical comb as described in claim 1, characterized in that: A multi-wavelength phase unwinding algorithm is used to reproduce the intensity and phase information of the measured light.

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