Sparsity based terahertz reflective off-axis digital holography

Wan, Min; Muniraj, Inbarasan; Malallah, Ra’ed; Zhao, Liang; Ryle, James P.; Rong, Lü; Healy, John J.; Wang, Dayong; Sheridan, John T.

doi:10.1117/12.2264788

Cited by 4 publications

(4 citation statements)

References 21 publications

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“…The first reports on successful camera-based THz holography used the pyroelectric detector Pyrocam III [105,106]. In later works, models with higher resolutions were used [107]. Decent signal-to-noise ratios (SNRs) can be achieved with pyroelectric cameras at the strongest line (2.52 THz) of far-infrared gas lasers (FIRLs), after multi-frame averaging and dead pixel replacement procedures to improve the SNR [106,108,109].…”

Section: Source-detector Systemsmentioning

confidence: 99%

THz coherent lensless imaging

et al. 2019

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Imaging with THz radiation has proved an important tool for both fundamental science and industrial use. Here we review a class of THz imaging implementations, named coherent lensless imaging, that reconstruct the coherent response of arbitrary samples with a minimized experimental setup based only on a coherent source and a camera. After discussing the appropriate sources and detectors to perform them, we detail the fundamental principles and implementations of THz digital holography and phase retrieval. These techniques owe a lot to imaging with different wavelengths, yet innovative concepts are also being developed in the THz range and are ready to be applied in other spectral ranges. This makes our review useful for both the THz and imaging communities, and we hope it will foster their interaction.

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Section: Source-detector Systemsmentioning

confidence: 99%

THz coherent lensless imaging

et al. 2019

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“…Frequency filtering techniques are often used for reducing the informative holographic data size considerably 39,40 .Currently, off-axis hologram compression is researched for problems in microscopy (images of red blood cells 14 , micro bio objects 15 , etc. ), terahertz systems 56 , 3D diffuse grayscale 57 and color 58 objects coding and imaging, computer-generated depth images representation 59 , next generation 3DTV applications 35,60 , quick volume scene displaying 61 , interferometry 15 , data multiplexing 62 , etc. Compression of off-axis digital holograms by binarization or direct quantization is used for visualization of optical scanning holographic data 63,64 , digital micromirror (DMD) applications 29,64 , fast printing and watermarking 65 , etc.There are two main aims of the paper:to compress single off-axis digital holograms using separation of the filtered spectrum into R/I parts andto perform a comparative analysis of the obtained results with those for compression by separation of the spectrum into A/P parts.Hologram compression based on a combination of a number of methods is analyzed, specifically,hologram frequency filtering,separation of the obtained spectrum into components,the wavelet transform, andadditional processing by quantization and thresholding.…”

Section: Introductionmentioning

confidence: 99%

“…Currently, off-axis hologram compression is researched for problems in microscopy (images of red blood cells 14 , micro bio objects 15 , etc. ), terahertz systems 56 , 3D diffuse grayscale 57 and color 58 objects coding and imaging, computer-generated depth images representation 59 , next generation 3DTV applications 35,60 , quick volume scene displaying 61 , interferometry 15 , data multiplexing 62 , etc. Compression of off-axis digital holograms by binarization or direct quantization is used for visualization of optical scanning holographic data 63,64 , digital micromirror (DMD) applications 29,64 , fast printing and watermarking 65 , etc.…”

Section: Introductionmentioning

confidence: 99%

Wavelet compression of off-axis digital holograms using real/imaginary and amplitude/phase parts

Cheremkhin

Курбатова

2019

Sci Rep

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Compression of digital holograms allows one to store, transmit, and reconstruct large sets of holographic data. There are many digital image compression methods, and usually wavelets are used for this task. However, many significant specialties exist for compression of digital holograms. As a result, it is preferential to use a set of methods that includes filtering, scalar and vector quantization, wavelet processing, etc. These methods in conjunction allow one to achieve an acceptable quality of reconstructed images and significant compression ratios. In this paper, wavelet compression of amplitude/phase and real/imaginary parts of the Fourier spectrum of filtered off-axis digital holograms is compared. The combination of frequency filtering, compression of the obtained spectral components, and extra compression of the wavelet decomposition coefficients by threshold processing and quantization is analyzed. Computer-generated and experimentally recorded digital holograms are compressed. The quality of the obtained reconstructed images is estimated. The results demonstrate the possibility of compression ratios of 380 using real/imaginary parts. Amplitude/phase compression allows ratios that are a factor of 2–4 lower for obtaining similar quality of reconstructed objects.

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“…Currently compression of off-axis digital holograms is used for the tasks of microscopy, metrology, fast 3D-object reconstruction, interferometry, and etc. [7][8][28][29][30].…”

Section: Introductionmentioning

confidence: 99%