Compact laser radar based on a subnanosecond laser diode transmitter and a two-dimensional CMOS single-photon receiver

Abstract

<div lang="en" class="abs"><p class="abs_header">Abstract</p><p>A pulsed TOF laser radar utilizing the single-photon detection mode has been implemented, and its performance is characterized. The transmitter employs a QW double-heterostructure laser diode producing 0.6 nJ∕100 ps laser pulses at a central wavelength of ∼810 nm. The detector is a single-chip IC manufactured in the standard 0.35-μmHV CMOS process, including a 9 × 9 single-photon avalanche diode (SPAD) array and a 10-channel time-to-digital converter (TDC) circuit. Both the SPAD array and the TDC circuit support a time gating feature allowing photon detection to occur only within a predefined time window. The SPAD array also supports a 3 × 3 SPADs subarray selection feature to respond to the laser spot wandering effect due to the paraxial optics and to reduce background radiation-induced detections. The characterization results demonstrate a distance measurement accuracy of þ∕ − 0.5 mm to a target at 34 m having 11% reflectivity. The signal detection rate is 28% at a laser pulsing rate of 100 kHz. The single-shot precision of the laser radar is ∼20 mm (FWHM). The deteriorating impact of high-level background radiation conditions on the SNR is demonstrated, as also is a scheme to improve this by means of detector time gating.</p></div>