Research On Multiplexing Technology For Single-photon LiDAR

Laser ranging technology has the advantages of fast measurement speed,high measurement accuracy,simple system structure and non-contact measurement,and is widely used in industrial detection,vehicle-mounted radar,geomorphology mapping and other fields.Compared with the traditional linear photoelectric light detection and ranging(Li DAR),the single-photon Li DAR(SPL)based on single-photon detection has higher detection sensitivity and longer measurement distance.Due to the limitation of the death time of single photon detector,the detection rate of SPL is far less than that of traditional linear photoelectric Li DAR.Multi-beam SPL technology improves the detection rate of SPL by detecting echo signals of multiple beams simultaneously,and makes up for the deficiency of SPL in detection rate.However,the multi-beam SPL system usually require single photon detectors and timers corresponding to the number of laser beams.The optical path structure of the system is complex,the scale of the core components of the system is large,and the installation and adjustment are difficult.Aiming at these problems,this paper studies the multiplexing technology applied to multi-beam SPL,so as to reduce the device scale required by the system and simplify the system structure.In this paper,technologies such as pulse time division multiplexing,wavelength division multiplexing,and pseudo-random pulse coding multiplexing are developed.Only one single-pixel single-photon detector is used to realize the simultaneous detection of multi-beam echoes,and realize the optical path structure of single-beam transceiver of multi-beam detection,which greatly simplifies the optical path system.The main innovations of the paper are as follows:1.Proposed multi-beam multiplexing detection technology of wavelength division multiplexing(WDM)and time division multiplexing(TDM)technology.Using WDM technology,16 distributed feedback lasers,dense wavelength division multiplexers,blazed gratings and other devices were used to build a 16-beam coaxial detection system with multi-beam detection and single beam transceiver.The field programmable gate array(FPGA)board used to time-division the pulse delay of the driving signals of the 16 lasers,and only one single-pixel near-infrared single-photon detector was used to detect the echo photons of all beams at the same time.The 16-beam single-photon imaging was realized,and the distance resolution of the system was 12 cm.The detection accuracy of the system reached 1.7 mm @ 1 s measurement time.2.Proposed multiplexed laser ranging technology based on pseudo-random pulse coding.8 groups of pseudo-random encoded pulse signals were used to drive 8 lasers with different wavelengths to generate 8 pseudo-random encoded laser pulses.Using the wavelength division multiplexed coaxial receiving and transmitting detection optical path,a single-pixel near-infrared single-photon detector was used to detect the echo photons of all beams at the same time.By calculating the correlation function between the detection signal and each group of pseudo-random codes,the time-of-flight detected by each laser was obtained,and multi-beam single-photon ranging and imaging were realized.The distance resolution of this system was 15 cm,and the detection accuracy reached 30 mm @ 1 s measurement time.