CN-122015635-A - Transmission-reflection-coordinated dual-wavelength digital holographic microscopic device and measurement method

CN122015635ACN 122015635 ACN122015635 ACN 122015635ACN-122015635-A

Abstract

The invention discloses a transmission-reflection cooperative dual-wavelength digital holographic microscopic device and a measurement method, wherein the device adopts a digital holographic microscopic method, orthogonal polarized laser emitted by two lasers with different wavelengths respectively enters a reference light and an object light transmission system, the reference light passes through a polarization multiplexing optical path unit to meet the requirement of dual-wavelength off-axis holographic spectrum separation, the object light passes through an object to be measured, when in a transmission mode, the object light interferes with one path of dual-wavelength reference light to record a transmission hologram, when in a reflection mode, the object light interferes with the other path of dual-wavelength reference light to record a reflection hologram, the optical path element is not required to be switched, and meanwhile, the transmission and reflection information of the object to be measured can be simultaneously acquired only through one-time imaging, so that the multiple operation optical paths in the measurement process are avoided, the measurement efficiency is improved, and the device is suitable for nondestructive dynamic monitoring of the object with large transmittance change and large longitudinal range.

Inventors

LIU YUN
LI RUI
ZHANG LEI
SHUI LINQI
WU MEIJI
XING JUNHONG

Assignees

西安理工大学

Dates

Publication Date: 20260512
Application Date: 20260130

Claims (10)

1. The trans-reflection cooperative dual-wavelength digital holographic microscopic device is characterized by comprising a first laser (1), a first polaroid (2), a first plane mirror (3), a second laser (4), a second polaroid (5), a first beam splitting prism (6), an attenuator (7), a beam expanding mirror (8), a second plane mirror (9), a first quarter wave plate (10), a polarization beam splitting prism (11), a second quarter wave plate (12), a third plane mirror (13), an optical isolator (14), a fourth plane mirror (15), a second beam splitting prism (16), a first lens (17), a first microscope objective (18), a sample to be detected (19), a second microscope objective (20), a second lens (21), a third beam splitting prism (22), a first camera (23), a fifth plane mirror (24), a first half wave plate (25), a fourth beam splitting prism (26), a second half wave plate (27), a sixth plane mirror (28), a fifth beam splitting prism (29) and a second camera (30); The first laser (1) and the second laser (4) respectively emit red light beams and green light beams, the red light beams emitted by the first laser (1) are modulated by a first polaroid (2) to output vertical vibration linear polarized red light, and then the vertical vibration linear polarized red light is reflected to a first beam splitting prism (6) by a first plane reflector (3), the green light beams emitted by the second laser (4) are modulated by a second polaroid (5) to output parallel vibration linear polarized green light, and the parallel vibration linear polarized green light is split into object light and reference light after being combined with the vertical vibration linear polarized red light beams at the first beam splitting prism (6); The reference light sequentially passes through an attenuation sheet (7) and a beam expander (8), and is re-divided into a vertically vibrating linear polarized red light beam and a parallel vibrating linear polarized green light beam at a polarization beam splitter prism (11), wherein the reflected vertically vibrating linear polarized red light is reflected by a second plane reflector (9) through a first quarter wave plate (10) and then passes through the first quarter wave plate (10) to become parallel vibrating linear polarized red light; the transmitted parallel vibration linear polarization green light is reflected by a third plane reflecting mirror (13) through a second quarter wave plate (12) and then is changed into vertical vibration linear polarization green light through the second quarter wave plate (12), the vertical vibration linear polarization green light and the parallel vibration linear polarization red light beam are recombined at a polarization splitting prism (11), the combined reference beam comprises two orthogonal linear polarization red light and linear polarization green light in the vibration direction, the reference beam is split into reference light I and reference light II at a fourth splitting prism (26), wherein the reference light I reaches a third splitting prism (22) through a first half wave plate (25), and the reference light II reaches a fifth splitting prism (29) through a second half wave plate (27); The object light is reflected to the second beam splitting prism (16) through the optical isolator (14) and then transmitted through the first lens (17) and the first micro-objective lens (18), and is divided into first transmitted light and second reflected light through the sample (19) to be detected, wherein the first transmitted light sequentially passes through the second micro-objective lens (20) and the second lens (21) and is reflected to the third beam splitting prism (22) through the fifth plane mirror (24), interferes with reference light and records a transmission hologram through the first camera (23), and the second reflected light sequentially passes through the first micro-objective lens (18) and the first lens (17), is reflected to the sixth plane mirror (28) through the second beam splitting prism (16), is reflected to the fifth beam splitting prism (29) through the sixth plane mirror (28), interferes with the second reference light and records a reflection hologram through the second camera (30).
2. The transflective coordinated dual-wavelength digital holographic microscopy device according to claim 1, wherein the first polarizing plate (2) and the second polarizing plate (5) are used for adjusting the polarization directions of two light beams emitted by the first laser (1) and the second laser (4) to be orthogonal, the attenuation plate (7) is used for adjusting the light intensity of object light to be consistent with that of reference light, the first half-wave plate (25) and the second half-wave plate (27) are used for guaranteeing interference between the first transmitted object light and the first reference light and between the second reflected object light and the second reference light, wherein the fast axis of the half-wave plate forms an angle of 45 degrees with the vertical direction, the vibration direction of the linearly polarized light is rotated by 90 degrees to be horizontal vibration when the linearly polarized light of the vertical vibration passes, and the linearly polarized light of the horizontal vibration is rotated by 90 degrees to be vertical vibration when the linearly polarized light of the horizontal vibration passes.
3. The transflective coordinated dual-wavelength digital holographic microscopy device according to claim 1, wherein the optical isolator (14) is used for unidirectional passage of light beam, preventing object light from being mixed with reference light, the first lens (17) and the first micro-objective lens (18) form a first telecentric light path structure, and the second micro-objective lens (20) and the second lens (21) form a second telecentric light path structure, for eliminating phase aberration.
4. The transflective coordinated dual-wavelength digital holographic microscopy device according to claim 1, wherein the second planar mirror (9) adjusts the included angle between the red light in the first reference light and the red light in the first transmitted light, the red light in the second reference light and the red light in the second reflected light by controlling the inclination angle of the mirror, and the third planar mirror (13) adjusts the included angle between the green light in the first reference light and the green light in the first transmitted light, the green light in the second reference light and the green light in the second reflected light by controlling the inclination angle of the mirror, so as to facilitate spectrum separation between the transmitted light path and the reflected light path and realize the off-axis dual-wavelength recording light path.
5. The transmission-reflection cooperative dual-wavelength digital holographic microscopy device according to claim 1, wherein the first beam splitting prism (6), the second beam splitting prism (16), the third beam splitting prism (22), the fourth beam splitting prism (26) and the fifth beam splitting prism (29) are depolarizing beam splitting prisms, and are used for splitting incident light beams into vertically vibrating linear polarized red light and parallel vibrating linear polarized green light according to a polarization state of the polarized beam splitting prisms (11), and the beam expander (8) is used for expanding light beams.
6. The method for measuring the transflective cooperative dual-wavelength digital holographic microscopy device according to any one of claims 1 to 5, comprising a transmission mode and a reflection mode, wherein the method comprises the following steps: A sample (19) to be tested is additionally arranged in a transmission-reflection cooperative dual-wavelength digital holographic microscopic device; turning on a first laser (1) and a second laser (4), acquiring a transmission hologram by a first camera (23), and acquiring a reflection hologram by a second camera (30); Based on the off-axis dual-wavelength digital holographic principle, reserving the positive primary frequency spectrum of each of red light and green light for the collected dual-wavelength digital transmission hologram or reflection hologram through frequency spectrum filtering, and removing interference of the zero-order and negative primary space frequency spectrum; Introducing the reproduction light identical with the reference light, digitally reconstructing the optical wave field complex amplitude on the image plane according to the angular spectrum principle by using a computer to simulate the diffraction process of the optical wave, and obtaining the wrapping phase information of the sample (19) to be detected by using the optical wave field complex amplitude; And (3) differentiating the wrapping phases of the red wavelength and the green wavelength, compensating the phase jump of the wrapping phases, and obtaining the phase of the equivalent synthetic wavelength, namely the phase information of the sample (19) to be detected.
7. The method of claim 6, wherein the intensity of the hologram superimposed by the red, green and green light is expressed as: (1); In the formula, Representing the spatial coordinates of the recording surface, And The light intensity of the red hologram and the light intensity of the green hologram are represented respectively, And Respectively representing the amplitude information of the red object light and the green object light, And Respectively representing phase information of the red object light and the green object light, And Respectively representing amplitude information of the red reference light and the green reference light, And Respectively representing phase information of the red reference light and the green reference light, And For the red light carrier frequency information, And For the green light carrier frequency information, The direct current component representing the hologram, spectrally represented as a central zero-order spectrum; The positive primary spectrum is a real image containing the phase information of the tested sample (19) and needs to be reserved, and the negative primary spectrum is a conjugate virtual image of the positive primary spectrum and needs to be removed as interference.
8. The method for measuring a transflective coordinated dual-wavelength digital holographic microscopy device according to claim 6, wherein the spectral filtering of the hologram can be expressed as: (2); (3); In the formula, And Representing the filtered red hologram and the filtered green hologram respectively, And Representing the fourier transform and the inverse fourier transform respectively, And Respectively representing a red spectral bandpass filter and a green spectral bandpass filter.
9. The method for measuring a dual-wavelength digital holographic microscopy device in cooperation with transmission and reflection according to claim 6, wherein the carrier modulation effect of the reference light can be removed by introducing the same reproduced light as the reference light, and the light field distribution of red light and green light can be expressed as: (4); (5); In the formula, And Respectively representing red light reproduction light and green light reproduction light; by simulating the diffraction process of the light wave by a computer, reconstructing the complex amplitude of the light wave field on the image plane according to the angular spectrum principle can be expressed as follows: (6); (7); In the formula, The spatial coordinates of the reproduction plane are represented, j represents an imaginary number, And Respectively the red wavelength and the green wavelength, Representing the axial distance the optical field propagates along the propagation direction; the wrapping phase information of the sample (19) to be measured obtained from the complex amplitude of the optical wave field can be expressed as: (8); (9); In the formula, The inverse tangent function is represented by a graph, And Representing the operations of taking the imaginary and real parts, respectively.
10. The method for measuring the dual-wavelength digital holographic microscopic device with the synergetic effect of transmission and reflection according to claim 6, wherein the wrapping phases of the red wavelength and the green wavelength are differenced and the phase jump is compensated, so as to obtain the phase of the equivalent synthetic wavelength, and the equivalent synthetic wavelength can be expressed as: (10); the phase of the equivalent synthetic wavelength, i.e. the phase information of the sample (19) to be measured, can be expressed as: (11)。

Description

Transmission-reflection-coordinated dual-wavelength digital holographic microscopic device and measurement method Technical Field The invention belongs to the field of optical interferometry, and particularly relates to a transmission-reflection-coordinated dual-wavelength digital holographic microscopic device and a measurement method. Background Digital holographic microscopy is a high-precision, non-contact and real-time three-dimensional measurement technology, and is widely applied to various fields such as microstructure morphology detection, biological cell morphology observation, refractive index distribution of micro optical elements and the like. In single wavelength digital holographic microscopy, when the adjacent height difference of the sample surface contains a non-continuous characteristic of more than one wavelength (transmission type) or half wavelength (reflection type) of the light source, the single wavelength digital holographic technology cannot accurately obtain the three-dimensional information of the sample to be measured. The dual-wavelength digital holographic microscopy technology irradiates a sample by using two light sources with different wavelengths to obtain interference holograms with different wavelengths, and can expand the longitudinal measurement range of the sample to a synthetic wavelength, namely, a single wavelength larger than any light source. Therefore, the dual-wavelength holographic microscopy can measure a measured object with a large longitudinal measuring range and a high aspect ratio, and has the advantages of large measuring range, high precision, non-contact and real-time measurement. The existing dual-wavelength digital holographic microscopy devices are mostly of single transmission type or reflection type structures, and for some measured objects with large transmittance changes, the whole measurement process cannot be completed by utilizing a single transmission or reflection mode. The existing single-wavelength digital holographic microscopic device with transmission and reflection modes can also finish measurement of the transmission or reflection mode on one device in a time-sharing way by switching the light path elements, and the change process of an object can not be dynamically monitored. Disclosure of Invention In order to overcome the defects of the device, the invention mainly aims to provide a transmission-reflection cooperative dual-wavelength digital holographic microscopic device and a measurement method. According to the invention, a switching device is not needed, the transmission and reflection cooperative measurement is realized, the real-time measurement of the transmission and reflection modes is completed only by one-time imaging, and meanwhile, the transmission and reflection information of the measured object is obtained, so that the device is suitable for the dynamic monitoring of the object with large change of the transmission and large longitudinal range, and the measurement efficiency and the measurement range of the device are effectively improved. In order to achieve the above purpose, the present invention adopts the following technical scheme: A transflective and cooperative dual-wavelength digital holographic microscopic device comprises a first laser 1, a first polaroid 2, a first plane reflector 3, a second laser 4, a second polaroid 5, a first beam splitting prism 6, an attenuation sheet 7, a beam expander 8, a second plane reflector 9, a first quarter wave plate 10, a polarization beam splitting prism 11, a second quarter wave plate 12, a third plane reflector 13, an optical isolator 14, a fourth plane reflector 15, a second beam splitting prism 16, a first lens 17, a first microscope objective 18, a sample 19 to be tested, a second microscope objective 20, a second lens 21, a third beam splitting prism 22, a first camera 23, a fifth plane reflector 24, a first half wave plate 25, a fourth beam splitting prism 26, a second half wave plate 27, a sixth plane reflector 28, a fifth beam splitting prism 29 and a second camera 30; The first laser 1 and the second laser 4 respectively emit red light beams and green light beams, the red light beams emitted by the first laser 1 are modulated by the first polarizer 2, output vertically vibrated linear polarized red light, and are reflected to the first beam splitter prism 6 by the first plane reflector 3, the green light beams emitted by the second laser 4 are modulated by the second polarizer 5, output parallel vibrated linear polarized green light, and are split into object light and reference light after being combined with the vertically vibrated linear polarized red light beams at the first beam splitter prism 6; The reference light sequentially passes through the attenuation sheet 7 and the beam expander 8, is re-divided into a vertically vibrating linear polarized red light beam and a parallel vibrating linear polarized green light beam at the polarization beam split