Improved terahertz phase sensing by using liquid crystal phase shifter

Ryota Ito; Michinori Honma; Toshiaki Nose

doi:10.1117/12.2543039

25 February 2020 Improved terahertz phase sensing by using liquid crystal phase shifter

Ryota Ito, Michinori Honma, Toshiaki Nose

Proceedings Volume 11303, Emerging Liquid Crystal Technologies XV; 113030M (2020) https://doi.org/10.1117/12.2543039
Event: SPIE OPTO, 2020, San Francisco, California, United States

Abstract

The use of terahertz waves for imaging has been studied intensively from the scientific, medical, and industrial viewpoints. Phase information is important for terahertz imaging and thus several kinds of phase detection methods for terahertz waves have been reported. Phase imaging using continuous wave terahertz interferometry has the advantage of having a high signal-to-noise ratio. Phase-shifting interferometry by using a liquid crystal (LC) phase shifter is a possible candidate for terahertz phase imaging. Accordingly, it has several advantages, such as a simple experimental setup and a low drive voltage. In our previous research, we confirmed that hydrogen-bonded LCs do not exhibit dichroism at 2.5 THz. Furthermore, hydrogen-bonded LCs exhibit higher birefringence in the terahertz range than in the visible range. Recently, we studied phase-shifting interferometry by using a hydrogen-bonded LC device. Since the hydrogen-bonded LC do not exhibit dichroism at 2.5 THz, the birefringence of the sample could be successfully obtained. To improve repeatability of this measurement, it is important to monitor the operational state of the LC phase shifter while making phase measurements. To simultaneously measure the phase of the sample and the degree of the phase shift of an LC device, we introduced a beam splitter and an additional detector into the phase-shifting interferometry technique. We report an improved measurement method for phase-shifting interferometry by using the LC phase shifter.

Citation Download Citation

Ryota Ito, Michinori Honma, and Toshiaki Nose "Improved terahertz phase sensing by using liquid crystal phase shifter", Proc. SPIE 11303, Emerging Liquid Crystal Technologies XV, 113030M (25 February 2020); https://doi.org/10.1117/12.2543039

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