On Laser Ranging Based on High-Speed/Energy Laser Diode Pulses and Single-Photon Detection Techniques

Abstract

This paper discusses the construction principles and performance of a pulsed time-of-flight (TOF) laser radar based on high-speed (FWHM $100 ps) and high-energy ($1 nJ) optical transmitter pulses produced with a specific laser diode working in an "enhanced gain-switching" regime and based on single-photon detection in the receiver. It is shown by analysis and experiments that single-shot precision at the level of 2W3 cm is achievable. The effective measurement rate can exceed 10 kHz to a noncooperative target (20% reflectivity) at a distance of 9 50 m, with an effective receiver aperture size of 2:5 cm 2 . The effect of background illumination is analyzed. It is shown that the gating of the SPAD detector is an effective means to avoid the blocking of the receiver in a high-level background illumination case. A brief comparison with pulsed TOF laser radars employing linear detection techniques is also made.

An 80 × 25 pixel CMOS single-photon image sensor with sub-ns time gating for solid state 3D scanning

“…Obviously, the accuracy of the depth measurement depends on the transmitted laser pulse width and distance measurement resolution of the detector. With a pulsed laser source that has high energy (Er > 1 nJ) and narrow full width at half maximum (FWHM ~ 100 ps), single-shot depth resolution of < 2 cm is achievable [8]. The detector time measurement precision depends on the SPAD timing jitter (50 -100 ps) and the time gating precision.…”

“…One part of the solution is to use optical filtering, carefully selecting the field of view of the receiver and using either a mechanical or electrical shutter. Range gating with fast electric shutter has been used in recent high-performance SPAD sensors to suppress the pile-up effect of unwanted photons arriving at the detector [7,8]. A SPAD imager operating principle that has been used in this work develops this idea further and decreases this time gating to the minimum.…”

High-energy sub-nanosecond optical pulse generation with a semiconductor laser diode for pulsed TOF laser ranging utilizing the single photon detection approach

“…The PDP is typically 5-2 % in the wavelength range of 800-900 nm meaning that approximately 50 photons per pulse are needed for a valid detection. This is about an order of magnitude less than what is needed in a typical linear receiver [4]. In addition, no separate analogue amplifier channel is needed which simplifies the receiver considerably.…”

“…Recently, it has been shown that the single photon detection (single photon avalanche detector, SPAD) mode presents a very interesting option for the receiver of a pulsed time-of-flight (TOF) laser radar [1][2][3][4]. The main advantages of the single photon detection compared to linear detection (e.g.…”

“…From the miniaturization point of view, this approach would benefit from the availability of semiconductor laser source producing highly energetic and short pulses with a characteristic pulse length on the scale of the jitter of the SPAD (*100 ps). Radiometric calculations show that a pulse energy of *1 nJ is needed for non-cooperative targets within a range of tens of meters from the emitter/receiver, with the size of optics of *5 cm 2 [4]. The achievable single shot precision of such a laser radar working in the single photon detection mode is set by the optical pulse width and the single photon detector response jitter.…”