Resolving range ambiguity in a photon counting depth imager operating at kilometer distances

Area of Science:

• Photonics and Optical Engineering
• 3D Imaging Technologies
• Laser Ranging Systems

Background:

• Time-correlated single-photon counting (TCSPC) is utilized in time-of-flight (ToF) ranging and depth imaging.
• Current TCSPC systems using periodic laser pulses require low repetition rates (<100 kHz) for unambiguous absolute range measurements over long distances (>1 km).
• This limitation restricts the data acquisition rate and the ability to generate high-resolution 3D images efficiently.

Purpose of the Study:

• To demonstrate a new pseudo-random pattern matching technique for scanning rangefinder systems.
• To overcome the ambiguity and low repetition rate limitations of traditional ToF systems.
• To enable unambiguous 3D image acquisition at significantly higher pulse rates.

Main Methods:

• Application of a pseudo-random pattern matching algorithm to a scanning rangefinder.
• Utilizing GHz base clock rates for enhanced measurement precision.
• Employing time-correlated single-photon counting to detect scattered return photons.

Main Results:

• Achieved unambiguous 3D image acquisition at average pulse rates exceeding 10 MHz.
• Demonstrated centimeter distance uncertainty for depth imaging.
• Successfully ranged objects between 50 m and 4.4 km.

Conclusions:

• The pseudo-random pattern matching technique effectively enhances the performance of ToF ranging systems.
• This method allows for high-speed, unambiguous 3D imaging, significantly improving upon existing TCSPC limitations.
• The developed system offers a viable solution for advanced depth imaging applications over extended ranges.