Compact Six-Degree-of-Freedom Displacement Sensing Based on Laser Reflection and Position-Sensitive Detectors

Chen, Jingyu; Li, Junjie; Diao, Yuan; Wang, Ke; Dong, Wenbo; Yu, Mengxi; Li, Zongfeng

doi:10.3390/photonics12111072

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Compact Six-Degree-of-Freedom Displacement Sensing Based on Laser Reflection and Position-Sensitive Detectors

by

Jingyu Chen

^1,2,†,

Junjie Li

^1,2,*,†

,

Yuan Diao

¹,

Ke Wang

¹

,

Wenbo Dong

¹

,

Mengxi Yu

¹ and

Zongfeng Li

^1,*

¹

Key Laboratory of Space Utilization, Technology and Engineering Center for Space Utilization, Chinese Academy of Sciences, Beijing 100094, China

²

University of Chinese Academy of Sciences, Beijing 100049, China

^*

Authors to whom correspondence should be addressed.

^†

These authors contributed equally to this work.

Photonics 2025, 12(11), 1072; https://doi.org/10.3390/photonics12111072

Submission received: 16 September 2025 / Revised: 21 October 2025 / Accepted: 28 October 2025 / Published: 29 October 2025

(This article belongs to the Special Issue New Progress in Optical Precision Measurement in the Field of Space Technology)

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Abstract

To meet pose-control and vibration-suppression requirements in confined spaces, a compact, noncontact six-degree-of-freedom (6-DoF) displacement-sensing method is proposed. The method is based on laser reflection and a position-sensitive detector (PSD) and features an adjustable incidence angle. An adjustable-incidence-angle PSD–corner-cube retro-reflector (CCR) configuration is devised, which reduces the PSD’s spatial footprint to 10.4% of that of a conventional layout. Building on this configuration, an analytical model is derived that maps the target’s 6-DoF displacement to the PSD spot motion as a function of the fixed relative pose between the PSD and the CCR mounted on the target. The model is linearized under the small-angle assumption. Experiments show an accuracy of 5.89 μm for translation within ±1.5 mm and 0.0027° for rotation within ±0.5°. The method couples a compact architecture with high precision and provides both a theoretical basis and an engineering-ready pathway for high-bandwidth pose sensing in confined spaces.

Keywords: displacement measurement; position-sensitive detector; laser reflection; corner-cube retro-reflector; small-angle approximation

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MDPI and ACS Style

Chen, J.; Li, J.; Diao, Y.; Wang, K.; Dong, W.; Yu, M.; Li, Z. Compact Six-Degree-of-Freedom Displacement Sensing Based on Laser Reflection and Position-Sensitive Detectors. Photonics 2025, 12, 1072. https://doi.org/10.3390/photonics12111072

AMA Style

Chen J, Li J, Diao Y, Wang K, Dong W, Yu M, Li Z. Compact Six-Degree-of-Freedom Displacement Sensing Based on Laser Reflection and Position-Sensitive Detectors. Photonics. 2025; 12(11):1072. https://doi.org/10.3390/photonics12111072

Chicago/Turabian Style

Chen, Jingyu, Junjie Li, Yuan Diao, Ke Wang, Wenbo Dong, Mengxi Yu, and Zongfeng Li. 2025. "Compact Six-Degree-of-Freedom Displacement Sensing Based on Laser Reflection and Position-Sensitive Detectors" Photonics 12, no. 11: 1072. https://doi.org/10.3390/photonics12111072

APA Style

Chen, J., Li, J., Diao, Y., Wang, K., Dong, W., Yu, M., & Li, Z. (2025). Compact Six-Degree-of-Freedom Displacement Sensing Based on Laser Reflection and Position-Sensitive Detectors. Photonics, 12(11), 1072. https://doi.org/10.3390/photonics12111072

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

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Compact Six-Degree-of-Freedom Displacement Sensing Based on Laser Reflection and Position-Sensitive Detectors

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