Solid-state block-based pulsed laser illuminator for single-photon avalanche diode detection-based time-of-flight 3D range imaging

Sahba S Jahromi,Jussi-Pekka Jansson,Eugene A Avrutin,Juha T Kostamovaara,Boris S Ryvkin,Pekka Keränen

doi:10.1117/1.oe.60.5.054105

Sahba S Jahromi, Jussi-Pekka Jansson + Show 4 more

Open Access

https://doi.org/10.1117/1.oe.60.5.054105

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Abstract

A laser diode illuminator for single-photon avalanche diode detection-based pulsed time-of-flight 3D range imaging is presented. The illuminator supports a block-based illumination scheme and consists of a 16-element custom-designed common anode quantum-well laser diode bar working in the enhanced gain switching regime and lasing at ∼810 nm. The laser diode elements are separately addressable and driven with gallium nitride drivers, which produce current pulses with a width of ∼2 ns; the current pulse amplitude was estimated from the supply voltage (90 V) as 5 to 10 A. Cylindrical optics are used to produce a total illumination field-of-view of 40 × 10 deg2 (full width at half maximum) in 16 separately addressable blocks. With a laser pulsing frequency of 256 kHz and laser pulse energy of ∼8.5 nJ, the average optical illumination power of the transmitter is 2.2 mW.

Highlights

One potential alternative for 3D range imaging is the pulsed time-of-flight (TOF) approach using CMOS single-photon avalanche detector (SPAD) techniques, in which a burst of short, powerful optical pulses produced with a laser diode transmitter is used to illuminate the field-ofview (FOV) of the system
This paper presents what we believe as the first published solid-state realization of a blockbased optical illuminator intended for SPAD-based pulsed TOF 3D range imaging
The key result of this work is a practical demonstration of a solid-state block-based illuminator realized relatively straightforwardly and in miniature size with a common anode laser diode bar and cylindrical optics

Summary

Introduction

One potential alternative for 3D range imaging is the pulsed time-of-flight (TOF) approach using CMOS single-photon avalanche detector (SPAD) techniques, in which a burst of short, powerful optical pulses produced with a laser diode transmitter is used to illuminate the field-ofview (FOV) of the system. One specific practical feature of this measurement technique is that, in the case of a typical measurement, the probability of a single SPAD element detecting a signal photon is substantially below one within most of the measurement range This means that it is necessary to transmit a number of optical pulses to achieve a valid detection for each pixel, i.e., a high enough signal-tonoise ratio (SNR). The number of signal detections in a given measurement time (defined by the desired frame rate) is exactly the same as it would be when using flood illumination with the same amount of average optical energy (assuming operation in single-photon detection regime, which holds for practical measurement cases).

Emitter Design

Laser Diode Bar Driver Electronics

Findings

Discussion and Summary