CN-121995718-A - Real-time quantitative phase detection device and method based on white light diffraction digital holography

CN121995718ACN 121995718 ACN121995718 ACN 121995718ACN-121995718-A

Abstract

A real-time quantitative phase detection device and method based on white light diffraction digital holography belongs to the technical field of optical imaging. The invention comprises a collimation light source, a light collecting lens, an aperture diaphragm, a converging lens, a polarizer, a polarization beam splitter prism and achromatism Wave plate, tube lens, microscope objective, measured reflection object, reflection concave grating, analyzer, space filter, positive lens, and 3CMOS camera. The spatial filter is located between the analyzer and the positive lens. According to the invention, a 3CMOS camera is adopted, three light intensity images of different channels are recorded respectively and simultaneously, white light diffraction digital holography is used for real-time quantitative phase detection, spatial multiplexing is realized through polarization regulation and control, complicated PU steps are omitted through halation effect compensation and TIE-based direct phase demodulation, complex amplitude distortion correction operation of DHM is avoided, and the robustness of the real-time quantitative phase detection device is improved. The invention can realize three-dimensional quantitative phase detection with high precision and high stability.

Inventors

CHENG WEIZHE
CHEN PING
WANG YABEI
LI YIHONG
LI PEIHONG
LIU KAIXIN

Assignees

中北大学

Dates

Publication Date: 20260508
Application Date: 20251231

Claims (9)

1. The real-time quantitative phase detection device based on white light diffraction digital holography is characterized by comprising a collimation light source, a light collecting lens, an aperture diaphragm, a converging lens, a polarizer, a polarization beam splitter prism and achromatism Wave plate, tube lens, microscope objective, measured reflection object, reflection concave grating, analyzer, space filter, positive lens, 3CMOS camera; the polarizer is positioned at the left side of the polarization beam splitter prism, and the analyzer is positioned at the right side of the polarization beam splitter prism, an achromatic color The wave plate is positioned above the tube mirror and below the polarization beam splitter prism, and the other one is achromatic The wave plate is positioned below the reflective concave grating and above the polarization beam splitter prism, the microscope objective is positioned below the tube lens, the spatial filter is positioned between the analyzer and the positive lens, and the 3CMOS camera is used for collecting images generated by interference of object light and reference light.
2. The apparatus of claim 1, wherein the collimated light source emits a parallel light beam through a condenser lens, an aperture stop, a condenser lens stop, and a condenser lens, the light beam passing through a polarizer to form a linearly polarized light of S polarization, the S polarized light passing through an achromatic color after being reflected by a polarization beam splitter prism The light carrying sample information is reflected by the sample and returned to the microscope objective, and the circularly polarized light is collimated into parallel light by the tube lens and passes through achromatism again A wave plate for converting the polarized light into linear polarized light of P polarization state, which sequentially passes through the polarization beam splitter prism and achromatism Wave plate for forming P polarized light and making it be incident into reflective concave grating, under the action of concave grating the incident P polarized light can form several diffraction orders convergent beams, and can be focused on different positions of focal plane of the described reflective concave grating, and passed through the process of achromatism The reflected S polarized light sequentially passes through an analyzer and a space filter positioned on the focal plane of the reflecting concave grating, then forms two parallel light beams with space included angles through the action of a positive lens, and is used as object light and reference light, the object light and the reference light interfere on the target surface of the 3CMOS camera to form a white light diffraction digital hologram, and the white light diffraction digital hologram is recorded by the camera.
3. The apparatus of claim 1 wherein the light beam, after being diffracted by the concave reflective grating, spatially forms a series of discrete, converging light beams of different diffraction orders due to the dispersive and concave focusing properties of the grating; A spatial filter is arranged at a common focal plane of the converging light beams, the spatial filter is a physical diaphragm with a clear aperture, the physical diaphragm comprises a slit and a pinhole array, by precisely adjusting the position of the spatial filter, the clear aperture is aligned only and allows two focuses of a 0-order diffraction light beam and a +1-order diffraction light beam to pass through, the focuses of the converging light beams of the other orders are blocked by a non-light-passing area of the spatial filter, the 0-order light beam and the +1-order light beam which are transmitted after being screened by the spatial filter are respectively and divergently transmitted after passing through the filter aperture, then the 0-order light beam and the +1-order light beam are incident on a positive lens, the positive lens is placed at a position where the front focal plane of the positive lens approximately coincides with the clear aperture plane of the spatial filter, the emergent light of the positive lens is converted into parallel light by the positive lens when the point light source is located on the front focal plane of the positive lens according to a geometrical optical principle, the two light beams of the 0-order and +1-order diffraction light beams are respectively collimated independently after passing through the positive lens, the two light beams of the 0-order diffraction light beam and the +1-order diffraction light beam are separated from the positive lens in a certain direction, and the two light beams are formed in a same space and the same direction as the front focal plane due to the fact that the two light beams are separated from the front focal plane in a certain direction The space included angle is determined by the separation distance of the two focuses and the focal length of the positive lens, wherein the +1 level light beam is object light, the 0 level light beam is reference light, the two parallel light beams with stable space included angle are jointly guided to the imaging target surface area of the 3CMOS camera, and because the two light beams come from the same light source, the two light beams have high space-time coherence, when meeting on the target surface of the camera, interference can occur to form stable space interference fringes, and the stable space interference fringes are recorded by the 3CMOS camera.
4. The method for real-time quantitative phase detection of information recorded by the device according to claim 1, comprising the steps of, Firstly, reconstructing +1-level spectrograms corresponding to red R, green G and blue B focusing state three-channel intensity patterns from single Zhang Caise digital holograms recorded by a 3CMOS camera respectively; The 3CMOS camera records interference pattern on its target surface to output a color digital hologram The hologram is a three-dimensional array at the data level, each pixel point thereof The information of (1) is formed by arranging and combining sub-pixel induction values corresponding to red light wavelength, green light wavelength and blue light wavelength according to a specific color filter array, and the original data Is the result of the spatial mosaic of the light intensity information of R, G, B spectral channels, according to the precise arrangement rule of the color filter array embedded in the camera To identify and separate the original sub-pixel data sets recording only red light intensity, only green light intensity and only blue light intensity, to generate three two-dimensional intensity matrixes which are identical to the spatial resolution of the original hologram and are completely aligned with the pixel positions 、、 The method comprises the steps of obtaining a single-color three-channel image, carrying out fast Fourier transform on R, G, B single-channel images, converting the images from a space domain to a frequency domain, outputting a complex matrix with the same size as the images of each channel, and marking as 、、 Wherein And Is a frequency domain coordinate; the modulus of the complex matrix intuitively represents the intensity distribution of different spatial frequency components in the image; and frequency shifting the complex matrix, the operation being achieved by exchanging four quadrants of the complex matrix; the method comprises the steps of translating zero frequency components of an original spectrum from corner positions of a matrix to the geometric center of a spectrogram, enabling the processed spectrum to be called a centered spectrum, enabling a central region of the processed spectrum to represent low-frequency components, enabling carrier frequency components caused by included angles between object light and reference light to be clearly identified on the periphery of the center of the spectrum, then identifying and extracting corresponding +1-level spectrums in each channel spectrogram after centering, searching for bright spots with significant energy concentration except for a central bright spot in amplitude distribution of the spectrum, symmetrically distributing the bright spots on two sides of the center according to an off-axis hologram interference principle, respectively corresponding to-1-level spectrums and +1-level spectrums, enabling +1-level spectrums to be particularly located in the energy concentration bright spots in a quadrant or direction which are determined in advance according to an optical path layout, enabling the positions of the bright spots to be accurately located on the basis of known object light, reference light and system parameters, enabling the carrier frequency components to be located in the actual spectrum by searching for a local intensity maximum region to be located in the center, defining a two-dimensional window function, utilizing the two-dimensional window as a center window, searching for the bright spots with the central window, extracting the bright spots with the same size as the initial spectral window, extracting the corresponding spectral coefficients, and extracting the spectral coefficients from the spectral coefficients, namely, and carrying out the original spectral coefficients, and the spectral coefficients, the spectral coefficients are completely being completely zero-dimensional data, and the spectral coefficients are completely extracted by the spectral coefficients, and the spectral coefficients are completely being extracted by the spectral coefficients, and the spectral coefficients are completely and the original spectral coefficients are completely and are extracted, and are completely and completely by the, new complex spectrum matrix, noted as 、、 ; Step two, reconstructing complex amplitude based on the TIE to obtain complex amplitude distribution of the reference light in different defocusing states; step three, performing complex amplitude compensation on +1-level spectrum information of the focused three-channel intensity map in the step one by utilizing the reference complex amplitude obtained in the step two; Step four, reconstructing corrected object light complex amplitude by adopting the corrected spectrum information of each channel through an angular spectrum diffraction propagation algorithm; And step five, propagating the object light complex amplitude obtained in the step four after the compensation to the same space reference plane, extracting the light intensity distribution on the plane, and directly demodulating the phase based on the TIE, namely realizing real-time quantitative phase detection.
5. The method of claim 4, wherein the second implementation method is, In the imaging light path, the +1 level object light of the space filter is shielded, only 0 level reference light is allowed to be irradiated to the target surface of the 3CMOS camera, a single Zhang Caise reference light intensity diagram under the focusing state is obtained, three single-color intensity images respectively corresponding to red light, green light and blue light wavelengths are separated from the color image according to the color image decoupling method, and the three single-color intensity images are recorded as 、、 The images directly reflect the two-dimensional intensity distribution of the reference light on the detection plane at different wavelengths according to the relation The square of the reference light amplitude is proportional to its intensity distribution, and therefore, the amplitude term of the reference light for each channel The intensity distribution is obtained by calculation; the +1 level object light of the shielding space filter only allows 0 level reference light to irradiate the target surface of the 3CMOS camera, and the reference light intensity images in the focusing, overfocusing and under-focusing states are acquired by moving the 3CMOS camera, single-color images in the focusing, overfocusing and under-focusing states under different channels are respectively acquired according to the color image decoupling method, the phase is calculated according to a TIE equation, and then the phase information of R, G, B three channels is acquired 、、 And reconstructing the complex amplitude of the reference light by combining the amplitude term with the phase information, and acquiring the complex amplitude distribution of the reference light in different defocusing states.
6. The method of claim 5, wherein the third implementation method is, By the formula Wherein Is the +1-level sidelobe signal obtained in the first step, Is the reference complex amplitude reconstructed from the TIE obtained in step two, Is the reference light intensity in the focused state, And decoupling object light and reference light complex amplitude to obtain +1-level spectrum information corrected under different channels.
7. The method of claim 6, wherein the fourth implementation method is, Using the formula The corrected +1 level spectrum information is multiplied by the angular spectrum transfer function to obtain the corrected object light angular spectrum under different channels, and the corrected angular spectrum is subjected to inverse Fourier transformation to finally obtain the corrected object light complex amplitude under different channels , , 。
8. The method of claim 7, wherein the fifth implementation method is, Amplitude of the object light complex at z=0 plane after R, G, B channel compensation , , Transforming its complex amplitude distribution into frequency domain by Fourier transformation to obtain three-channel correspondent angular spectrum, using the angular spectrum transfer function mentioned in the fourth step to make it be propagated into same space reference plane parallel to initial plane, and making it have a distance along optical axis Multiplying the angular spectrum of the initial plane z=0 with the angular spectrum transfer function of the corresponding channel by a formula to obtain the propagated angular spectrum Transforming the transmitted angular spectrum back to the spatial domain to obtain angular spectra of each channel in the same spatial reference plane Three object light complex amplitude distributions: red channel object light complex amplitude; The object light complex amplitude of the green channel; blue channel object light complex amplitude and using formula , Obtaining three-channel light intensity distribution on the same space plane 、、 Then calculating the axial differential of the light intensity through chromatic aberration, further solving a TIE equation to obtain a solved phase, and solving the obtained phase Converted to the actual height of the sample Real-time quantitative phase demodulation based on white light diffraction digital holography is realized, namely real-time quantitative phase detection is realized.
9. The method of claim 8, wherein the two-dimensional window function is a rectangular window or a circular window.

Description

Real-time quantitative phase detection device and method based on white light diffraction digital holography Technical Field The invention belongs to the technical field of optical imaging, and relates to a device and a method for real-time quantitative phase detection based on white light diffraction digital holography. Background The Quantitative phase microscopic imaging technology based on complex amplitude reconstruction benefits from the non-marking and non-invasive characteristics, can perform high-precision and high-sensitivity Quantitative phase imaging (Quantitative PHASE IMAGING, QPI) on a pure-phase sample, and overcomes the defect that the conventional optical microscope cannot acquire Quantitative phase information of the sample due to high-dependence on intensity contrast imaging without a complex optical path structure, so that the Quantitative phase microscopic imaging technology has important research value and application potential. In particular, in the field of optical precision machining manufacturing, high precision QPI for micro device surface type and structure can be used as an important means for defect detection and quality assessment. In the field of quantitative phase microscopy imaging, imaging modes based on interference and non-interference are all long and face different challenges and opportunities. In addition, the prior art still does not get rid of the dilemma of the traditional imaging mode in terms of calculation efficiency, imaging mode, dynamic measurement, technology contrast fusion, structural optimization and the like when facing flexible and changeable measurement requirements. In order to ensure the stability and high contrast of the interference pattern, a high coherence light source is widely adopted in QPI technology based on interferometry, but the high coherence light source can cause the acquired wrapping phase to be subjected to crosstalk of noise such as Gaussian, speckle, discontinuous truncation and the like, so that the measurement precision and space-time sensitivity of the system are reduced. Compared to the QPI approach of interferometry, non-interferometric techniques suppress the effects of coherent noise by employing partially coherent or incoherent illumination. Among them, TIE-based non-interferometric QPI techniques have attracted considerable attention because of the elimination of the unwrapping (Phase Unwrapping, PU) step and the realization of direct imaging of absolute phases. Like other non-interfering approaches, TIE-based QPI typically requires expensive equipment or complex optical paths and corrective algorithms. Therefore, the QPI technology of interference and non-interference measurement has an optimization space in terms of improving the measurement precision and space-time sensitivity of the system, and a set of compact optical system can be established through innovative structural design to realize the contrast and advantage complementation of digital holography (Digitai Holography Microscopy, DHM) and TIE technologies. Disclosure of Invention In order to solve the problems of coherent noise crosstalk, phase unwrapping, complex iterative computation, halation effect and the like in the prior art, the invention aims to provide a real-time quantitative phase detection device and method based on white light diffraction digital holography, which are used for real-time quantitative phase detection, and the method omits complex PU steps through direct phase demodulation based on TIE, avoids complex amplitude distortion correction operation of DHM and improves the robustness of the real-time quantitative phase detection device. The invention is applied to the field of optical precision machining and manufacturing, and can realize three-dimensional quantitative phase detection with high precision and high stability. In order to achieve the above purpose, the invention is realized by the following technical scheme: The invention discloses a real-time quantitative phase detection device based on white light diffraction digital holography, which comprises a collimation light source, a light collecting lens, an aperture diaphragm, a converging lens, a polarizer, a polarization beam splitter prism and achromatism Wave plate, tube lens, microscope objective, measured reflection object, reflection concave grating, analyzer, space filter, positive lens, and 3CMOS camera. The polarizer is positioned at the left side of the polarization beam splitter prism, and the analyzer is positioned at the right side of the polarization beam splitter prism. Achromatism methodThe wave plate is positioned above the tube mirror and below the polarization beam splitter prism. Another achromaticThe wave plate is positioned below the reflective concave grating and above the polarization beam splitter prism. The microscope objective is arranged below the tube lens. The spatial filter is located between the analyzer and the positive lens. The 3CMOS camera is use