CN-116339097-B - Dual-wavelength digital holographic system and method

CN116339097BCN 116339097 BCN116339097 BCN 116339097BCN-116339097-B

Abstract

The invention relates to a dual-wavelength digital holographic system and a method, wherein the system comprises an LED illumination module, a polarizer, a polarization filter device, an objective table device, an infinite imaging microscope objective lens, a lens barrel lens, an orthogonal grating, a first lens, a spatial filter, a second lens and a monochromatic black-and-white image sensor which are sequentially connected. According to the technical scheme provided by the invention, the holographic imaging precision is improved under the condition of simplifying the system architecture.

Inventors

ZHONG LIYUN
LI HONGYUN
LIU LIN
Han Xianxin
ZHOU CHENGXIN
LV XIAOXU

Assignees

华南师范大学

Dates

Publication Date: 20260505
Application Date: 20230223

Claims (9)

1. The dual-wavelength digital holographic system is characterized by comprising an LED illumination module, a polarizer, a polarization filter device, an objective table device, an infinite imaging microscope objective, a lens barrel lens, an orthogonal grating, a first lens, a spatial filter, a second lens and a monochromatic black-and-white image sensor which are sequentially connected, wherein: After the polarization direction of the light emitted by the LED lighting module is adjusted by the polarizer, the light vertically enters the polarization filter device so as to generate two illumination light waves with different wavelengths and mutually orthogonal polarization directions by the polarization filter device; The illumination light waves penetrate through a sample to be detected placed on the object stage device, and imaging light beams scattered by the sample to be detected are collected by the infinity imaging microscope objective, converged by the lens cone lens and then diffracted by the orthogonal grating; the 0-order diffraction light generated by the orthogonal grating propagates according to an original path and is used as reference light after passing through the spatial filter, and the two +1-order diffraction light beams are converged by the first lens and are respectively used as two object light beams after passing through the spatial filter; the object light and the reference light filtered by the spatial filter are converged on an imaging surface of the monochrome black-and-white image sensor through the second lens, and the monochrome black-and-white image sensor captures and records the object light and the reference light to obtain orthogonal carrier frequency interference fringes; The polarization filtering device comprises a first Wollaston prism, a third lens, a first optical filter, a second optical filter, a fourth lens and a second Wollaston prism which are sequentially arranged along the light beam propagation direction; wherein the first Wollaston prism is positioned on the front focal plane of the third lens, the second Wollaston prism is positioned on the back focal plane of the fourth lens, and the first optical filter and the second optical filter are distributed on different paths between the third lens and the fourth lens; The first Wollaston prism is used for shearing off the linear polarized illumination light waves output by the polarizer, the first optical filter and the second optical filter are used for generating illumination light waves with different wavelengths, and the second Wollaston prism is used for recombining the illumination light waves with different wavelengths.
2. The system of claim 1, wherein the first filter has a center wavelength of 590nm, the second filter has a center wavelength of 633nm, and the first filter and the second filter each have a half-width of 1nm.
3. The system of claim 1, wherein the spatial filter comprises a first means for filtering the 0 th order diffracted light transmitted through the orthogonal grating into a desired uniform spherical wave and as a reference beam in interference, a second means for allowing only light polarized in the x-direction to pass through and obtaining a first object light after filtering, and a third means for allowing only light polarized in the y-direction to pass through and obtaining a second object light after filtering.
4. The system of claim 1, wherein the LED lighting module has a center wavelength of 610nm and a full width at half maximum of 50nm.
5. The system of claim 1, wherein the orthogonal grating is located on a back focal plane of the tube lens and is configured to converge two beams of orthogonally polarized light having an angle to a same location to achieve wavefront matching of the reference light and the object light.
6. A dual wavelength digital holographic method for use in the system of any of claims 1 to 5, the method comprising: After the outgoing light is polarized in the direction, two illumination light waves with different wavelengths and mutually orthogonal polarization directions are generated; The imaging light beams scattered by the illumination light waves through the sample to be detected are converged to generate diffracted light; The 0-order diffraction light propagates according to the original path and forms reference light, and the two +1-order diffraction light is filtered into two object light after converging; the object light and the reference light are converged on an imaging surface to generate orthogonal carrier frequency interference fringes.
7. The method of claim 6, wherein generating two illumination light waves having different wavelengths and mutually orthogonal polarization directions after the outgoing light is polarized in the direction of adjustment comprises: After the polarization direction of the light emitted by the LED lighting module is adjusted by the polarizer, the light vertically enters the polarization filter device so as to generate two illumination light waves with different wavelengths and mutually orthogonal polarization directions by the polarization filter device.
8. The method of claim 6, wherein generating diffracted light after the imaging light beam scattered by the illumination light wave through the sample to be measured is focused comprises: the illumination light waves penetrate through a sample to be detected placed on the object stage device, imaging light beams scattered by the sample to be detected are collected by an infinite imaging microscope objective lens and are converged through a lens barrel lens, and diffraction is carried out through an orthogonal grating, so that diffracted light is generated.
9. The method of claim 6, wherein converging the object light and the reference light onto an imaging plane to generate orthogonal carrier frequency interference fringes comprises: the object light and the reference light filtered by the spatial filter are converged on an imaging surface of a monochromatic black-and-white image sensor through a second lens, and the monochromatic black-and-white image sensor captures and records the object light and the reference light to obtain orthogonal carrier frequency interference fringes.

Description

Dual-wavelength digital holographic system and method Technical Field The invention relates to the technical field of holographic imaging, in particular to a dual-wavelength digital holographic system and a dual-wavelength digital holographic method. Background The digital holographic microscopy is a high-precision optical measurement technology for quantitatively obtaining the phase distribution of a sample by combining the traditional optical microscopy imaging technology with the holographic imaging technology, has the characteristics of no damage, full view field, rapidness, non-contact, high precision and the like, and is widely applied to surface microscopic morphology measurement and biological cell imaging. Conventional digital holographic microscopy requires constructing the wrapped phases from holograms and then unwrapping the wrapped phases into a continuous phase map using an unwrapping algorithm. The disadvantage is also significant, the unpacking algorithm is computationally intensive and may result in unpacking failure when the sample has too high a jump. In order to solve the above problems, dual-wavelength digital holography is proposed. The advantage of dual wavelength digital holography over single wavelength digital holographic microscopy is that this technique gives a larger synthetic wavelength by selecting two wavelengths, theoretically allowing measurement of samples with higher heights and larger hops. In addition, the technology uses two light beams with different wavelengths to measure the sample, can continuously record phase information under a plurality of different wavelengths, and obtains a phase difference of the two light beams to obtain a phase diagram with equivalent wavelength. Because the synthetic wavelength is larger than any one of the introduced wavelengths, the technology can greatly improve the measurement range of digital holographic microscopy. However, in the field of dual-wavelength digital holography research, two lasers with different wavelengths are generally required for introducing synthesized wavelengths, so that the cost is high, and meanwhile, a large amount of noise is brought by two coherent light sources with different wavelengths in an interference light path, so that the accuracy of phase recovery is greatly affected. On the other hand, most of the current dual-wavelength digital holography technologies are based on the non-common-path structure of Mach-Zeng Dehuo Michelson interferometer, and both light beams are subject to environmental interference, so that the time stability of the system is poor, the fringes are unstable, and a considerable phase error is generated. Therefore, there is a need for a dual-wavelength digital holographic system with a more compact architecture and with a higher accuracy. Disclosure of Invention In view of the foregoing, it is desirable to provide a dual-wavelength digital hologram system and method that improves the accuracy of holographic imaging while simplifying the system architecture. In order to achieve the above object, according to an aspect of the present invention, there is provided a dual-wavelength digital hologram system, the system comprising an LED illumination module, a polarizer, a polarization filter device, a stage device, an infinity imaging microscope objective, a tube lens, a quadrature grating, a first lens, a spatial filter, a second lens, and a monochrome black-and-white image sensor, which are sequentially connected, wherein: After the polarization direction of the light emitted by the LED lighting module is adjusted by the polarizer, the light vertically enters the polarization filter device so as to generate two illumination light waves with different wavelengths and mutually orthogonal polarization directions by the polarization filter device; The illumination light waves penetrate through a sample to be detected placed on the object stage device, and imaging light beams scattered by the sample to be detected are collected by the infinity imaging microscope objective, converged by the lens cone lens and then diffracted by the orthogonal grating; the 0-order diffraction light generated by the orthogonal grating propagates according to an original path and is used as reference light after passing through the spatial filter, and the two +1-order diffraction light beams are converged by the first lens and are respectively used as two object light beams after passing through the spatial filter; and converging the object light and the reference light filtered by the spatial filter on an imaging surface of the monochromatic black-and-white image sensor through the second lens, and capturing and recording by the monochromatic black-and-white image sensor to obtain orthogonal carrier frequency interference fringes. In one embodiment, the polarization filtering device comprises a first Wollaston prism, a third lens, a first optical filter, a second optical filter, a fourth lens and a second Wol