An experimental study on terahertz light field data acquisition and digital refocusing

Yang Moxuan; Zhao Yuanmeng; Zuo Jian; Lv Nanfang; Zhang Cunlin

doi:10.12086/oee.2020.190670

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Yang M X, Zhao Y M, Zuo J, et al. An experimental study on terahertz light field data acquisition and digital refocusing[J]. Opto-Electron Eng, 2020, 47(5): 190670. doi: 10.12086/oee.2020.190670

Citation:

Yang M X, Zhao Y M, Zuo J, et al. An experimental study on terahertz light field data acquisition and digital refocusing[J]. Opto-Electron Eng, 2020, 47(5): 190670. doi: 10.12086/oee.2020.190670

An experimental study on terahertz light field data acquisition and digital refocusing

Key Laboratory of Terahertz Optoelectronics, Ministry of Education; Beijing Key Laboratory for Terahertz Spectroscopy and Imaging; Beijing Advanced Innovation Center for Imaging Theory and Technology; Department of Physics, Capital Normal University, Beijing 100048, China

Fund Project: Supported by "the 2020 Connotation Development Funds for Interdisciplinary Academic Construction" of Graduate School of Capital Normal University

More Information

Corresponding author: Zhao Yuanmeng, E-mail:zhao.yuanmeng@cnu.edu.cn

Received Date 02 November 2019

Revised Date 14 April 2020

Published Date 01 May 2020

Abstract

Abstract

In recent years, terahertz imaging has attracted great attention due to its advantages including penetrability and nondestructive property. The field imaging technology within the terahertz range is expected to enhance the terahertz image quality and improve its application effect. In this paper, an experiment on the data acquisition and digital refocusing of the terahertz light field was conducted. Firstly, the basic principle, system structure, and the method of reconstructing light field imaging were analyzed. Secondly, the terahertz focal plane array camera was used to collect the data about light field and digital refocusing was used to get the computed imaging. Finally, the reconstructed image was enhanced to obtain higher depth resolution, angle resolution, and object contour resolution. Experimental results showed the feasibility and ability of terahertz light field imaging to improve image quality and enrich retrieval effects.
- terahertz /
- light field acquisition /
- digital refocusing /
- image reconstruction

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References

[1]	速晋辉, 金易弢, 陆艺丹, 等.光场图像重构算法仿真[J].光学仪器, 2017, 39(1): 31-40. Google Scholar Su J H, Jin Y T, Lu Y D, et al. Simulation of the algorithms for the light field image rendering[J]. Optical Instruments, 2017, 39(1): 31-40. Google Scholar
[2]	聂云峰, 相里斌, 周志良.光场成像技术进展[J].中国科学院研究生院学报, 2011, 28(5): 563-572. Google Scholar Nie Y F, Xiang L B, Zhou Z L. Advances in light field photography technique[J]. Journal of the Graduate School of the Chinese Academy of Sciences, 2011, 28(5): 563-572. Google Scholar
[3]	Gershun A. The light field[J]. Journal of Mathematics and Physics, 1939, 18(1-4): 51-151. doi: 10.1002/sapm193918151 CrossRef Google Scholar
[4]	Gabor D. A new microscopic principle[J]. Nature, 1948, 161(4098): 777-778. doi: 10.1038/161777a0 CrossRef Google Scholar
[5]	Levoy M, Hanrahan P. Light field rendering[C]//Proceedings of the 23rd Annual Conference on Computer Graphics and Interactive Techniques, 1996: 31-42. Google Scholar
[6]	赵国忠.太赫兹科学技术研究的新进展[J].国外电子测量技术, 2014, 33(2): 1-6, 20. doi: 10.3969/j.issn.1002-8978.2014.02.001 CrossRef Google Scholar Zhao G Z. Progress on terahertz science and technology[J]. Foreign Electronic Measurement Technology, 2014, 33(2): 1-6, 20. doi: 10.3969/j.issn.1002-8978.2014.02.001 CrossRef Google Scholar
[7]	Hu B B, Nuss M C. Imaging with terahertz waves[J]. Optics Letters, 1995, 20(16): 1716-1718. doi: 10.1364/OL.20.001716 CrossRef Google Scholar
[8]	Xu J M, Chen L, Zang X F, et al. Triple-channel terahertz filter based on mode coupling of cavities resonance system[J]. Applied Physics Letters, 2013, 103(16): 161116. doi: 10.1063/1.4826456 CrossRef Google Scholar
[9]	姚建铨.太赫兹技术及其应用[J].重庆邮电大学学报(自然科学版), 2010, 22(6): 703-707. Google Scholar Yao J Q. Introduction of THz-wave and its applications[J]. Journal of Chongqing University of Posts and Telecommunications (Natural Science Edition), 2010, 22(6): 703-707. Google Scholar
[10]	Jain R, Grzyb J, Pfeiffer U R. Terahertz light-field imaging[J]. IEEE Transactions on Terahertz Science and Technology, 2016, 6(5): 649-657. Google Scholar
[11]	肖照林.基于相机阵列的光场成像与深度估计方法研究[D].西安: 西北工业大学, 2014. Google Scholar Xiao Z L. Camera array based light field imaging and depth estimation[D]. Xi'an: Northwestern Polytechnical University, 2014.http://cdmd.cnki.com.cn/Article/CDMD-10699-1015031013.htm Google Scholar
[12]	Wilburn B, Joshi N, Vaish V, et al. High performance imaging using large camera arrays[J]. ACM Transactions on Graphics, 2005, 24(3): 765-776. doi: 10.1145/1073204.1073259 CrossRef Google Scholar
[13]	Lumsdaine A, Georgiev T. The focused plenoptic camera[C]//Proceedings of 2009 IEEE International Conference on Computational Photography, 2009: 1-8. Google Scholar
[14]	王丽娟, 张骏, 张旭东, 等.局部搜索式的Lytro相机微透镜阵列中心标定[J].光电工程, 2016, 43(11): 19-25. doi: 10.3969/j.issn.1003-501X.2016.11.004 CrossRef Google Scholar Wang L J, Zhang J, Zhang X D, et al. Micro-lens array center calibration via local searching using Lytro cameras[J]. Opto-Electronic Engineering, 2016, 43(11): 19-25. doi: 10.3969/j.issn.1003-501X.2016.11.004 CrossRef Google Scholar
[15]	Veeraraghavan A, Raskar R, Agrawal A, et al. Dappled photography: mask enhanced cameras for heterodyned light fields and coded aperture refocusing[J]. ACM Transactions on Graphics, 2007, 26(3): 69. doi: 10.1145/1276377.1276463 CrossRef Google Scholar
[16]	Green P, Sun W Y, Matusik W, et al. Multi-aperture photography[J]. ACM Transactions on Graphics, 2007, 26(3): 68. doi: 10.1145/1276377.1276462 CrossRef Google Scholar
[17]	张春萍, 王庆.光场相机成像模型及参数标定方法综述[J].中国激光, 2016, 43(6): 0609004. Google Scholar Zhang C P, Wang Q. Survey on imaging model and calibration of light field camera[J]. Chinese Journal of Lasers, 2016, 43(6): 0609004. Google Scholar
[18]	Wang Y Q, Yang J G, Guo Y L, et al. Selective light field refocusing for camera arrays using bokeh rendering and superresolution[J]. IEEE Signal Processing Letters, 2019, 26(1): 204-208. doi: 10.1109/LSP.2018.2885213 CrossRef Google Scholar
[19]	石梦迪, 张旭东, 董运流, 等.一种双引导滤波的光场去马赛克方法[J].光电工程, 2019, 46(12): 180539. doi: 10.12086/oee.2019.180539 CrossRef Google Scholar Shi M D, Zhang X D, Dong Y L, et al. A light field demosaicing method with double guided filtering[J]. Opto-Electronic Engineering, 2019, 46(12): 180539. doi: 10.12086/oee.2019.180539 CrossRef Google Scholar

Overview

Overview

Overview: As a highly versatile computational imaging method, light field imaging has attracted great attention and has rapidly developed in the past 20 years. Light field imaging with visible light has been widely applied. Terahertz radiation has many advantages such as good penetrability and effective bandwidth. The combination of light field imaging and terahertz radiation will enrich the concept of light field imaging.

Firstly, this article introduced the characteristics of terahertz waves, summarized the historical development of light field photography, and analyzed the basic principle of terahertz light field imaging. Based on the method of capturing, 4D light field, the typical light field photography devices are categorized into single scanning imaging camera, camera array imaging, integral imaging, aperture coded, optical mask, etc. The terahertz light field imaging technology, a kind of computational imaging method within the terahertz band, takes advantage of terahertz focal plane array camera to collect a series of target sub-image arrays from different directions and angles, then, uses the digital refocusing to get the computed imaging and image reconstruction technology to obtain image. However, the reconstructed image appears blurry with unclear boundary. In order to reduce adverse effects, the image edge feature was combined with Laplace operator to enhance images, thus obtaining the refocusing images of light field with higher depth resolution, angle resolution, and object contour resolution at different depths.

Experimental results showed the feasibility and ability of terahertz light field imaging to improve image quality and enrich retrieval effects. The successful combination of terahertz radiation and light field imaging technology provides unique characteristics for future research. For example, it overcomes the limitation of traditional visible light imaging by optical lens and sensor or the size of the aperture. Terahertz light filed imaging technology can take advantage of the characteristics of the wave to achieve image in the dark environment. In a word, the light field imaging quality is effectively improved by the above method. It lays a foundation for establish a three-dimensional reconstruction and synthetic aperture imaging algorithm by removing the foreground of terahertz light field imaging.