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High-Speed and Cost-Effective Reflective Terahertz Imaging System Using a Novel 2D Beam Scanner
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- Authors
- Eui Su Lee, Mugeon Kim, Kiwon Moon, Il-Min Lee, Dong Woo Park, Jun-Hwan Shin, Hyun-Soo Kim, Da-Hye Choi, Kyeong Sun Choi, Dong Hun Lee, Kyung Hyun Park
- Issue Date
- 2020-08
- Citation
- IEEE/OSA Journal of Lightwave Technology, v.38, no.16, pp.4237-4243
- ISSN
- 0733-8724
- Publisher
- Optical Society of America (OSA)
- Language
- English
- Type
- Journal Article
- Abstract
- Nondestructive THz imaging technology is a promising technology in several industrial applications such as process monitoring and quality control. To further popularize the application of this technique in the industry, we developed photonics-based devices such as a dual-mode laser, uni-travelling carrier photodiode, and Schottky-barrier diode that enable the realization of a compact, low-cost, multifunctional continuous wave (CW) THz system. To develop CW THz reflective imaging systems with these devices, a telecentric f-罐 lens and novel two-dimensional (2D) beam scanner were developed. A high-speed, low-cost 2D reflector with a 4-sided polygon mirror, a brushless DC (BLDC) motor rotating at approximately 2,990 revolutions per minute (RPM) and a stepping motor was designed to ensure that a THz image sized 500 × 400 pixels could be scanned in approximately 2 s. However, it is difficult to maintain a constant speed in high-speed rotating BLDC motors. The measured maximum deviation is approximately 0.7%, which results in distorted images. To compensate for this distortion, a sync signal reflector was designed to monitor the real-time RPM of the BLDC motor. Using the novel 2D beam scanner and sync signal reflector, the distorted images could be corrected simply, enabling the development of a 2D THz reflective imaging system using a single emitter and detector; this system could exhibit a higher speed and was more cost effective than the existing system. Although further improvements to photonics-based THz technologies are necessary, we believe that these efforts will begin an era of THz technologies as a widely used industrial technique.
- KSP Keywords
- 2D beam, Brushless dc (BLDC) motor, Dual-mode laser, High-speed rotating, Imaging technology, Industrial Applications, Low-cost, Polygon mirror, Process monitoring, Quality Control, Real-time