Abstract
We demonstrate a reflectivity and depth imaging Lidar system based on a novel photon arrival time measurement method. In this method, the arrival time of photons in a scanning position is continuously measured with a common starting point. The number of laser pulses is counted by a specially designed field programmable gate array (FPGA) control module as the coarse time of arrival photon. Time interval between arrival photon and the nearest coming laser pulse is measured by a time-correlated single-photon counting (TCSPC) module as the fine time of arrival photon. Using the system, not only the single-photon counting imaging can be realized, but also the first photon imaging, the first two photons imaging, etc. can be realized. A photon statistical model based on the doubly stochastic Poisson point processes, a time-gated filtering algorithm, and the reflectivity algorithm based on maximum likelihood estimation are derived. High-sensitivity reflectivity and depth imaging with a resolution of 512 × 512 pixels are achieved. The experimental results show that the horizontal spatial resolution is 2 mm, the vertical depth resolution is 5.375 cm, and the average number of photons per pixel is less than 1.3 photons.
Highlights
Single-photon counting Lidar has become a research hotspot for a number of remote sensing applications in recent years [1], [2]
A photon statistical model based on the doubly stochastic Poisson point processes, a time-gated filtering algorithm, and the reflectivity algorithm based on maximum likelihood estimation are derived
The experimental results show that the horizontal spatial resolution is 2 mm, the vertical depth resolution is 5.375 cm, and the average number of photons per pixel is less than 1.3 photons
Summary
Single-photon counting Lidar has become a research hotspot for a number of remote sensing applications in recent years [1], [2]. The reflection intensity and depth of the surface of the long-distance object can be recovered by counting the number of photons in the laser echo signals and measuring time-of-flight (TOF) of the photons [6]. A Lidar based on a combination of a single-photon detector and a low power semiconductor laser can satisfy the detection of long-range objects in the atmospheric environment [7], [8] and airborne remote sensing [9] with strict limits on weight, size and volume. This paper presents a continuous, high-precision method for measuring arrival time of photons with a common starting point in a scanning position In this method, the number of laser pulses is counted by a field programmable gate array (FPGA) control module as the coarse time of arrival photon. Single-photon counting imaging of the long-range object can be achieved, and the first photon imaging, the first two photons imaging, etc. can be realized
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