Improvement of acquisition time using high speed MEMS bolometer in active imaging

Isao Morohashi; Ya Zhang; Boqi Qiu; Norihiko Sekine; Kazuhiro Hirakawa; Iwao Hosako

doi:10.1117/12.2553016

11 March 2020 Improvement of acquisition time using high speed MEMS bolometer in active imaging

Isao Morohashi, Ya Zhang, Boqi Qiu, Norihiko Sekine, Kazuhiro Hirakawa, Iwao Hosako

Proceedings Volume 11331, Fourth International Conference on Photonics Solutions (ICPS2019); 1133104 (2020) https://doi.org/10.1117/12.2553016
Event: Fourth International Conference on Photonic Solutions (ICPS 2019), 2019, Chiang Mai, Thailand

Abstract

For establishing terahertz (THz) imaging with rapid scan, the influence of the response speed of a microelectromechanical system (MEMS) bolometer on the image quality have been evaluated and compared it with a pyroelectric detector (PED). The MEMS bolometer was operated with the frequency modulation detection mode in which the frequency shift due to the illumination of the laser light is tracked by a phase-locked loop (PLL) system. In the detection system using the PED, the laser light was chopped by an optical chopper and output signals were measured by a lock-in amplifier. Output signals from the detection systems were recorded by an analog-to-digital converter (ADC). An etched metal bookmark was used for the imaging object and imaging was made by a combination of continuous scans in the X direction and step scans in the Z direction. In imaging using the MEMS bolometer under a stage speed of 25 mm/s, the fine structures composed of very small holes much smaller than 1 mm were clearly observed. The images acquired by the MEMS bolometer were almost the same quality regardless of the stage speed, while in the case of the PED the images were distorted with increasing the stage speed. This is due to the bandwidth of the detectors. These results imply that the MEMS bolometer enables to acquire images with rapid scanning.

Citation Download Citation

Isao Morohashi, Ya Zhang, Boqi Qiu, Norihiko Sekine, Kazuhiro Hirakawa, and Iwao Hosako "Improvement of acquisition time using high speed MEMS bolometer in active imaging", Proc. SPIE 11331, Fourth International Conference on Photonics Solutions (ICPS2019), 1133104 (11 March 2020); https://doi.org/10.1117/12.2553016

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