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

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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.