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Holography|10 Article(s)
A Comprehensive Review on Parallel Phase-shifting Digital Holography（Invited）
Meiling ZHANG, Peng GAO, Kai WEN, Kequn ZHUO, Yang WANG, Lixin LIU, Junwei MIN, and Baoli YAO
Phase-shifting Digital Holography（PSDH），which combines phase-shifting technology with digital holography， provides a fast， non-invasive， and high-precision approach for the three-dimensional morphology or refractive index distribution of microscopic objects. Compared with the off-axis digital holography， the phase-shifting on-axis digital holography makes full utilization of Spatial-bandwidth Product （SBP） of the CCD camera. The conventional phase-shifting digital holography needs to records multiple phase-shifting holograms in a step-by-step manner， from which the artifact-free phase and amplitude images of a sample can be reconstructed. To enhance the imaging speed of PSDH， parallel phase-shifting technique （or simultaneous phase-shifting technique） was proposed， with which multiple phase-shifting holograms can be obtained at the same time. In this paper， the concept and implementation of phase-shifting technologies are introduced firstly. Then， three different approaches of parallel phase-shifting， which are based on multiple CCDs， pixelated phase-mask， and parallel beam-splitting， are reviewed. Eventually， the applications of parallel PSDH in the biomedical field， air/liquid flow visualization， surface topography， micro-/nano-scale device inspection are introduced. Phase-shifting Digital Holography（PSDH），which combines phase-shifting technology with digital holography， provides a fast， non-invasive， and high-precision approach for the three-dimensional morphology or refractive index distribution of microscopic objects. Compared with the off-axis digital holography， the phase-shifting on-axis digital holography makes full utilization of Spatial-bandwidth Product （SBP） of the CCD camera. The conventional phase-shifting digital holography needs to records multiple phase-shifting holograms in a step-by-step manner， from which the artifact-free phase and amplitude images of a sample can be reconstructed. To enhance the imaging speed of PSDH， parallel phase-shifting technique （or simultaneous phase-shifting technique） was proposed， with which multiple phase-shifting holograms can be obtained at the same time. In this paper， the concept and implementation of phase-shifting technologies are introduced firstly. Then， three different approaches of parallel phase-shifting， which are based on multiple CCDs， pixelated phase-mask， and parallel beam-splitting， are reviewed. Eventually， the applications of parallel PSDH in the biomedical field， air/liquid flow visualization， surface topography， micro-/nano-scale device inspection are introduced.
Acta Photonica Sinica
- Publication Date: Jul. 25, 2021
- Vol. 50, Issue 7, 1 (2021)
Nonlinear Reconstruction for Off-axis Fresnel Digital Holography with Deep Learning
Hang LIU, Yong-liang XIAO, Jun-long TIAN, Hong-xing LI, and Jian-xin ZHONG
A nonlinear reconstruction method with a single digital hologram using deep learning was proposed for off-axis Fresnel digital hologram. Classic Fresnel diffraction integral is utilized for simulating digital holographic imaging to provide the training samples, and a deep convolution residual neural network is utilized to implement on the object image reconstruction from the recorded hologram, by learning the nonlinear mathematical mapping from the digital hologram to the corresponding object image. The results of numerical simulation experiments show that the method could directly eliminate zero-order images and twin images without fringe pre-processing procedure for extracting object term, compared with the traditional frequency filtering and four-step phase-shift techniques for achieving Fresnel digital holography reconstruction, as well as high quality reconstructed object image. It also has strong robustness to the test dateset generated with different diffraction distances using same recording reference light waveform. A nonlinear reconstruction method with a single digital hologram using deep learning was proposed for off-axis Fresnel digital hologram. Classic Fresnel diffraction integral is utilized for simulating digital holographic imaging to provide the training samples, and a deep convolution residual neural network is utilized to implement on the object image reconstruction from the recorded hologram, by learning the nonlinear mathematical mapping from the digital hologram to the corresponding object image. The results of numerical simulation experiments show that the method could directly eliminate zero-order images and twin images without fringe pre-processing procedure for extracting object term, compared with the traditional frequency filtering and four-step phase-shift techniques for achieving Fresnel digital holography reconstruction, as well as high quality reconstructed object image. It also has strong robustness to the test dateset generated with different diffraction distances using same recording reference light waveform.
Acta Photonica Sinica
- Publication Date: Aug. 25, 2020
- Vol. 49, Issue 7, 709001 (2020)
Design of Waveguide Holographic Configuration for Display
LIU Yu-jie, DING Quan-xin, LI Wen-qiang, and YAN Zhan-jun
In a holographic waveguide display system, the inconformity of grating parameters of input grating, turning grating and output leads to a lot of difficulties in system design and gratings fabrication process. The main condition that the turning grating should be in 60° conical mounting, on which all the gratings in a waveguide holographic display configuration have uniform grating periods, was presented by comparing the grating equations in normal mounting and conical mounting. Under this condition, a novel efficient display was proposed by using a waveguide holographic configuration with three holographic gratings of the same grating periods recorded on a single substrate and a reflector placed on the side face of the substrate. The validity of this configuration was proved by the simulation carried out by the optical design software CODE V. The coupling efficiency loss and invalid area can be dramatically reduced by the reflector on the side face, compared with the traditional configuration. Moreover, the complexity of system design and holographic manufacture can be decreased because all gratings used in the proposed design have uniform grating periods and two of them have uniform orientation. The configuration can be applied to virtual reality display or wearable display. In a holographic waveguide display system, the inconformity of grating parameters of input grating, turning grating and output leads to a lot of difficulties in system design and gratings fabrication process. The main condition that the turning grating should be in 60° conical mounting, on which all the gratings in a waveguide holographic display configuration have uniform grating periods, was presented by comparing the grating equations in normal mounting and conical mounting. Under this condition, a novel efficient display was proposed by using a waveguide holographic configuration with three holographic gratings of the same grating periods recorded on a single substrate and a reflector placed on the side face of the substrate. The validity of this configuration was proved by the simulation carried out by the optical design software CODE V. The coupling efficiency loss and invalid area can be dramatically reduced by the reflector on the side face, compared with the traditional configuration. Moreover, the complexity of system design and holographic manufacture can be decreased because all gratings used in the proposed design have uniform grating periods and two of them have uniform orientation. The configuration can be applied to virtual reality display or wearable display.
Acta Photonica Sinica
- Publication Date: Jan. 01, 2015
- Vol. 44, Issue 3, 309003 (2015)
New Methods of Removing Background and Applications in In-line Digital Holography
WU Xiu-pin, and GAO Wan-rong
Background decrease method and adaptive filtering methods were proposed to solve the background removing problem in digital holographic microscopy in the in-line digital holographic microscopy.In-line digital holography microscopic system was set up, with which the digital holographic images of onion epidermis, the plant roots′ sample, the lamina stoma sample and the blood cell sample were reconstructed, respectively.In addition, the advantages of the proposed methods were demonstrated by calculating the light intensity distribution curves and the values of the contrast of images obtained with the in-line digital holographic microscope device.The results show that the backgrounds in the measured holographic interferometric fringes change with the experimental conditions and the sample itself.So that the backgrounds could be divided into three types, for each of which an appropriate method was proposed to achieve the best reconstruction image quality.The results may be helpful for reconstructing the better quality images. Background decrease method and adaptive filtering methods were proposed to solve the background removing problem in digital holographic microscopy in the in-line digital holographic microscopy.In-line digital holography microscopic system was set up, with which the digital holographic images of onion epidermis, the plant roots′ sample, the lamina stoma sample and the blood cell sample were reconstructed, respectively.In addition, the advantages of the proposed methods were demonstrated by calculating the light intensity distribution curves and the values of the contrast of images obtained with the in-line digital holographic microscope device.The results show that the backgrounds in the measured holographic interferometric fringes change with the experimental conditions and the sample itself.So that the backgrounds could be divided into three types, for each of which an appropriate method was proposed to achieve the best reconstruction image quality.The results may be helpful for reconstructing the better quality images.
Acta Photonica Sinica
- Publication Date: Jan. 01, 2015
- Vol. 44, Issue 3, 309002 (2015)
A Method to Improve Fringe Contrast in Time-average Digital Holography for Vibration Measurement
XIAO Wen, ZHANG Xu-hong, PAN Feng, CONG Lin, and LI Yan
A new algorithm was proposed to improve vibration-related fringes contrast for micro-vibration online detection based on time-average digital holography. First, phase change arising from the longitudinal micro-displacement of the object during vibrating process was corrected. Then phase noise caused by speckle noise was eliminated, and thus fringes pattern contrast that modulated by Bessel function was improved effectively. Finally, the amplitude distribution of the measuring surface was estimated according to Bessel function and fringe progressions. An experimental system based on time-average digital holographic interferometry was proposed for micro-vibration measurement that acoustic wave was used for excitation source. The experiment was verified by the reed that excited at the sinusoidal frequency of 0, 1 100, 2 000 and 9 000 Hz, respectively. The result based on vibration frequency of 2 000 Hz shows that the proposed method can improve vibration-related fringes contrast effectively. Amplitude of three-order zero points are 109.4 nm, 244.2 nm and 356.4 nm, and errors are 6.31%, 3.34% and 3.78%, respectively, compared with theoretical values, which demonstrate the effectiveness of the method within the allowable range. A new algorithm was proposed to improve vibration-related fringes contrast for micro-vibration online detection based on time-average digital holography. First, phase change arising from the longitudinal micro-displacement of the object during vibrating process was corrected. Then phase noise caused by speckle noise was eliminated, and thus fringes pattern contrast that modulated by Bessel function was improved effectively. Finally, the amplitude distribution of the measuring surface was estimated according to Bessel function and fringe progressions. An experimental system based on time-average digital holographic interferometry was proposed for micro-vibration measurement that acoustic wave was used for excitation source. The experiment was verified by the reed that excited at the sinusoidal frequency of 0, 1 100, 2 000 and 9 000 Hz, respectively. The result based on vibration frequency of 2 000 Hz shows that the proposed method can improve vibration-related fringes contrast effectively. Amplitude of three-order zero points are 109.4 nm, 244.2 nm and 356.4 nm, and errors are 6.31%, 3.34% and 3.78%, respectively, compared with theoretical values, which demonstrate the effectiveness of the method within the allowable range.
Acta Photonica Sinica
- Publication Date: Jan. 01, 2015
- Vol. 44, Issue 3, 309001 (2015)
Polarization Holographic Grating Recording in Spiropyran Doped Polymers Under Bi-photonic Irradiations
ZHENG Mei-ling, XIE Xin, SU Ling-li, LI Ben-tian, FU Shen-cheng, SHI Feng, and WANG Xiu-li
The exposure sensitivity and polarization sensitivity of spiropyran doped polymers after the irradiation in short-wavelength range were significantly improved. Based on such properties, holographic grating recordings accompanying with a linearly polarized blue-violet beam (405 nm) in the photochromic film were performed by two coherent green beams (532 nm) for s-p formation. Under the bi-photonic action of 405 nm and 532 nm, temporal evolution of diffraction efficiency was strongly dependent on auxiliary light intensity. It was found the blue-violet irradiation plays double roles in holographic recordings: on one hand, providing the molecular orientationable merocyanine for the recording beams;on the other, disrupting the formation of refractive index gratings and reducing the conversion activity of merocyanine molecule.Taking the existence of merocyanine aggregation in the random light field of interference fringes into account, an theoretical model was established which reveals the relationship between diffraction efficiency and light-rate-constant of each molecular.The experimental results are precisely fitted with this model, the microscopic reaction mechanism of spiropyran and merocyanine molecules in polarization holographic recording was effectively explained. The exposure sensitivity and polarization sensitivity of spiropyran doped polymers after the irradiation in short-wavelength range were significantly improved. Based on such properties, holographic grating recordings accompanying with a linearly polarized blue-violet beam (405 nm) in the photochromic film were performed by two coherent green beams (532 nm) for s-p formation. Under the bi-photonic action of 405 nm and 532 nm, temporal evolution of diffraction efficiency was strongly dependent on auxiliary light intensity. It was found the blue-violet irradiation plays double roles in holographic recordings: on one hand, providing the molecular orientationable merocyanine for the recording beams;on the other, disrupting the formation of refractive index gratings and reducing the conversion activity of merocyanine molecule.Taking the existence of merocyanine aggregation in the random light field of interference fringes into account, an theoretical model was established which reveals the relationship between diffraction efficiency and light-rate-constant of each molecular.The experimental results are precisely fitted with this model, the microscopic reaction mechanism of spiropyran and merocyanine molecules in polarization holographic recording was effectively explained.
Acta Photonica Sinica
- Publication Date: Jan. 01, 2015
- Vol. 44, Issue 2, 209003 (2015)
Optimization of Output Gratings in Holographic Waveguide Display System
PENG Fei, ZHANG Pan, YANG De-xing, KANG Ming-wu, and MA Bai-heng
In a holographic waveguide display system, the diffraction efficiency, location, and length of each ouput grating make great impact on the uniformity of output intensity and ratio of energy utilization. Generally uniformity of output intensity is decided by the diffraction efficiency distribution of each output grating, and ratio of energy utilization rests with the location and length of each ouput grating. Firstly, aming at the uniformity of central field of view, the diffraction efficiency distribution of corresponding output grating was optimized and curve fitting, and a continuous and increasing curve of efficiency distribution was obtained. Similar processing was carried out for other gratings corresponding to other FOV. Calculation results demonstrate that the uniformity of output intensity of HWDS will be improved notablely when output gratings with optimized continuous and increasing diffraction efficiency distributions are used than that of traditional output gratings with step diffraction efficiency distributions. A shifting-optimization method was proposed to optimize the location of each grating according to the size of exit pupil and usage distance, so that the ratio of energy utilization of HWDS could be greatly incereased resulted from the reduction of the invalid diffraction region. In a holographic waveguide display system, the diffraction efficiency, location, and length of each ouput grating make great impact on the uniformity of output intensity and ratio of energy utilization. Generally uniformity of output intensity is decided by the diffraction efficiency distribution of each output grating, and ratio of energy utilization rests with the location and length of each ouput grating. Firstly, aming at the uniformity of central field of view, the diffraction efficiency distribution of corresponding output grating was optimized and curve fitting, and a continuous and increasing curve of efficiency distribution was obtained. Similar processing was carried out for other gratings corresponding to other FOV. Calculation results demonstrate that the uniformity of output intensity of HWDS will be improved notablely when output gratings with optimized continuous and increasing diffraction efficiency distributions are used than that of traditional output gratings with step diffraction efficiency distributions. A shifting-optimization method was proposed to optimize the location of each grating according to the size of exit pupil and usage distance, so that the ratio of energy utilization of HWDS could be greatly incereased resulted from the reduction of the invalid diffraction region.
Acta Photonica Sinica
- Publication Date: Jan. 01, 2015
- Vol. 44, Issue 2, 209002 (2015)
Method for Choosing Angle of Reference Beam in Computer-generated Holograms Based on Spatial Frequency Analysis of Principle Fringe Pattern
HUANG Ying-qing, ZHAO Kai, PEI Chuang, YAN Xing-peng, and JIANG Xiao-yu
A method for choosing angle of reference beam in computer-generated holograms based on spatial frequency analysis of principle fringe pattern was proposed. The rules for reconstructed image rightly were obtained through analyzing the spatial frequency of principle fringe pattern. The angles of reference beam in the holography reconstructed system based on spatial light modulator were computed. The holograms of one image plane with size of 22.5 mm×26.1 mm were generated at the distance of 1 000 mm when different angles of reference beam were chosen. The digital and optical reconstructed experiments were conducted respectively. The results indicate that the angle of reference beam must be chosen in the range which is from 0.893 8° to 1.398 0° in order to achieve good quality of reconstructed images. If the angle of reference beam is smaller than 0.893 8°, the reconstructed image and the conjugate image could not be separated completely, whereas the reconstructed image would overlap with the conjugate image of the next order if the angle of reference beam is larger than 1.398 0°. The experimental results validate the theoretical analysis very well. A method for choosing angle of reference beam in computer-generated holograms based on spatial frequency analysis of principle fringe pattern was proposed. The rules for reconstructed image rightly were obtained through analyzing the spatial frequency of principle fringe pattern. The angles of reference beam in the holography reconstructed system based on spatial light modulator were computed. The holograms of one image plane with size of 22.5 mm×26.1 mm were generated at the distance of 1 000 mm when different angles of reference beam were chosen. The digital and optical reconstructed experiments were conducted respectively. The results indicate that the angle of reference beam must be chosen in the range which is from 0.893 8° to 1.398 0° in order to achieve good quality of reconstructed images. If the angle of reference beam is smaller than 0.893 8°, the reconstructed image and the conjugate image could not be separated completely, whereas the reconstructed image would overlap with the conjugate image of the next order if the angle of reference beam is larger than 1.398 0°. The experimental results validate the theoretical analysis very well.
Acta Photonica Sinica
- Publication Date: Jan. 01, 2015
- Vol. 44, Issue 2, 209001 (2015)
IMPLEMENTATION OF THREE-DIMENSION STEREOSCOPIC DISPLAY WITH A PARTIAL-PIXEL HOLOGRAPHIC SCREEN
[in Chinese], and [in Chinese]
Acta Photonica Sinica
- Publication Date: Jan. 01, 2002
- Vol. 31, Issue 4, 467 (2002)
COLOR TRANSMISSION HOLOGRAM
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Acta Photonica Sinica
- Publication Date: Jan. 01, 2002
- Vol. 31, Issue 4, 463 (2002)
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