Polarization-Modulated Optical Homodyne for Time-of-Flight Imaging with Standard CMOS Sensors
Indirect time-of-flight (iToF) imaging is a widely applied technique to obtain a depth image from the phase difference of amplitude-modulated signals between emitted light and reflected light. The phase difference is computed via electrical correlation on a conventional iToF sensor. However, iToF se...
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MDPI AG
2025-03-01
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| Online Access: | https://www.mdpi.com/1424-8220/25/6/1886 |
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| author | Ayaka Ebisu Takahito Aoto Tsuyoshi Takatani |
| author_facet | Ayaka Ebisu Takahito Aoto Tsuyoshi Takatani |
| author_sort | Ayaka Ebisu |
| collection | DOAJ |
| description | Indirect time-of-flight (iToF) imaging is a widely applied technique to obtain a depth image from the phase difference of amplitude-modulated signals between emitted light and reflected light. The phase difference is computed via electrical correlation on a conventional iToF sensor. However, iToF sensors face a trade-off between spatial resolution and light collection efficiency because it is hard to downsize the circuit of the electrical correlation in a pixel. Thus, we propose a novel iToF depth imaging system based on polarization-modulated optical homodyne detection with a standard CMOS sensor. A resonant photoelastic modulator is employed to modulate the polarization state, enabling optical correlation through interaction with an analyzer. The homodyne detection enhances noise resistance and sensitivity in the phase difference estimation. Furthermore, the use of a polarization camera allows to reduce the number of measurements. We first validate the successful estimation of the phase difference in both setups with an avalanche photodiode or a CMOS sensor. The experimental results show accurate depth estimation even in challenging factors such as a low signal-to-noise ratio, temporal intensity variations, and speckle noise. The proposed system enables high-resolution iToF depth imaging using readily available image sensors. |
| format | Article |
| id | doaj-art-ef07a17f5cff412a86704b20fcd490e0 |
| institution | DOAJ |
| issn | 1424-8220 |
| language | English |
| publishDate | 2025-03-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Sensors |
| spelling | doaj-art-ef07a17f5cff412a86704b20fcd490e02025-08-20T02:43:07ZengMDPI AGSensors1424-82202025-03-01256188610.3390/s25061886Polarization-Modulated Optical Homodyne for Time-of-Flight Imaging with Standard CMOS SensorsAyaka Ebisu0Takahito Aoto1Tsuyoshi Takatani2Deggree Programs in Systems and Information Engineering, University of Tsukuba, Tsukuba 305-8573, JapanOptech Innovation, LLC., Tsukuba 305-0031, JapanInstitute of Systems and Information Engineering, University of Tsukuba, Tsukuba 305-8573, JapanIndirect time-of-flight (iToF) imaging is a widely applied technique to obtain a depth image from the phase difference of amplitude-modulated signals between emitted light and reflected light. The phase difference is computed via electrical correlation on a conventional iToF sensor. However, iToF sensors face a trade-off between spatial resolution and light collection efficiency because it is hard to downsize the circuit of the electrical correlation in a pixel. Thus, we propose a novel iToF depth imaging system based on polarization-modulated optical homodyne detection with a standard CMOS sensor. A resonant photoelastic modulator is employed to modulate the polarization state, enabling optical correlation through interaction with an analyzer. The homodyne detection enhances noise resistance and sensitivity in the phase difference estimation. Furthermore, the use of a polarization camera allows to reduce the number of measurements. We first validate the successful estimation of the phase difference in both setups with an avalanche photodiode or a CMOS sensor. The experimental results show accurate depth estimation even in challenging factors such as a low signal-to-noise ratio, temporal intensity variations, and speckle noise. The proposed system enables high-resolution iToF depth imaging using readily available image sensors.https://www.mdpi.com/1424-8220/25/6/1886depth imagingspatial resolutionoptical correlationphotoelastic modulator |
| spellingShingle | Ayaka Ebisu Takahito Aoto Tsuyoshi Takatani Polarization-Modulated Optical Homodyne for Time-of-Flight Imaging with Standard CMOS Sensors Sensors depth imaging spatial resolution optical correlation photoelastic modulator |
| title | Polarization-Modulated Optical Homodyne for Time-of-Flight Imaging with Standard CMOS Sensors |
| title_full | Polarization-Modulated Optical Homodyne for Time-of-Flight Imaging with Standard CMOS Sensors |
| title_fullStr | Polarization-Modulated Optical Homodyne for Time-of-Flight Imaging with Standard CMOS Sensors |
| title_full_unstemmed | Polarization-Modulated Optical Homodyne for Time-of-Flight Imaging with Standard CMOS Sensors |
| title_short | Polarization-Modulated Optical Homodyne for Time-of-Flight Imaging with Standard CMOS Sensors |
| title_sort | polarization modulated optical homodyne for time of flight imaging with standard cmos sensors |
| topic | depth imaging spatial resolution optical correlation photoelastic modulator |
| url | https://www.mdpi.com/1424-8220/25/6/1886 |
| work_keys_str_mv | AT ayakaebisu polarizationmodulatedopticalhomodynefortimeofflightimagingwithstandardcmossensors AT takahitoaoto polarizationmodulatedopticalhomodynefortimeofflightimagingwithstandardcmossensors AT tsuyoshitakatani polarizationmodulatedopticalhomodynefortimeofflightimagingwithstandardcmossensors |