1. A Nearly Interference-Free and Depth-Resolution-Configurable Time-of-Flight System Based on a Mega-Pixel Vertical Avalanche Photodiodes CMOS Image Sensor
- Author
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Shota Yamada, Motonori Ishii, Shigetaka Kasuga, Masato Takemoto, Hiromu Kitajima, Toru Okino, Yusuke Sakata, Manabu Usuda, Yugo Nose, Hiroshi Koshida, Masaki Tamaru, Akito Inoue, Yuki Sugiura, Shigeru Saito, Taiki Kunikyo, Yusuke Yuasa, Kentaro Nakanishi, Naoki Torazawa, Takashi Shirono, Tatsuya Kabe, Shinzo Koyama, Mitsuyoshi Mori, Yutaka Hirose, Masayuki Sawada, Akihiro Odagawa, and Tsuyoshi Tanaka
- Subjects
Avalanche photodiode ,vertical avalanche photodiode ,time-of-flight ,CMOS image sensor ,photon counting ,ranging ,Electric apparatus and materials. Electric circuits. Electric networks ,TK452-454.4 - Abstract
We present a long range (~250 m) time-of flight (TOF) system with suppressed (nearly-free) mutual-interference. The system is based on a $1296\times960$ pixels vertical avalanche photodiodes (VAPD) CMOS image sensor (CIS). Real-time long-range 3D-imaging with 30 fps speed (450 fps for 2D imaging) is demonstrated. Designs and operation principles of the core circuits, i.e., a photon counting circuit and a global shutter driver, are fully described. The ranging method is based on a sub-range synthesis (SRS) where a range is set by the phase of exposure pulses with respect to that of the light source of the system. The depth resolution is configurable in that the minimum sub-range width limited by the light source pulse width of 10 ns or 1.5 m can be reduced to a 10 cm by introducing an indirect-TOF operation. Furthermore, by employing a random flight timing (RFT), mutual-interference in raw signal level is suppressed by 35 dB when 2 cameras are simultaneously operated. By simulation, the present system is estimated to be tolerant up to a case of 27 cameras operation.
- Published
- 2022
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