Proc. SPIE. 10978, Advanced Photon Counting Techniques XIII
KEYWORDS: Near infrared, CMOS sensors, Imaging systems, Cameras, LIDAR, Sensors, Silicon, Single photon, Image sensors, Single photon detectors, 3D image processing, Direct detection LIDAR, Single-photon counters, Time of flight range image sensors
Initial results of electrical and optical characterization of Voxtel’s first generation 256 x 256 dual-mode silicon singlephoton avalanche diode (SPAD) image sensor are presented. The SPAD image sensor is a dual-mode device capable of sequential passive single-photon-counting (2D) and active single-photon lidar (3D) range imaging at greater than 250 frames per second, full-frame. The sensor was developed in 180-nm complementary metal-oxide semiconductor imagesensor technology with a pixel pitch of 30 μm and fill factor of 9%; and it achieves room temperature per-pixel dark count rate of less than 55 Hz (0.63 Hz/μm2), peak photon detection probability of 29% (at 480 nm) and timing jitter of 268 ps full width at half maximum at the optimal operating point. Preliminary imaging results in 2D and 3D mode are presented.
The latest three-dimensional imaging results from Voxtel teamed with the University are Dayton are presented using Voxtel’s VOX3D™ series flash lidar camera. This camera uses the VOX3D series flash lidar sensor which integrates a 128×128 InGaAs p-i-n detector array with a custom, multi-mode, low-noise, complementary metal-oxide semiconductor readout integrated circuit. In this paper, results are presented of: short-range (< 10 m) three-dimensional lidar imaging performed at University of Dayton with a fast, low-power eye safe laser (20-μJ per pulse, 10-kHz) in high-bandwidth, windowed region-of-interest mode; and longer range (30 – 150 m) outdoor lidar tests performed at Voxtel with two different eye safe lasers (300-μJ and 3-mJ per pulse, 10-Hz) in full-frame low-bandwidth mode. The VOX3D camera achieves a single-shot timing precision of 23.2 cm and 10.7 cm in high-bandwidth and low-bandwidth modes respectively, with the timing precision in high bandwidth mode being limited by camera electronics. The VOX3D camera has a maximum range of 51 m and 159 m with 300-μJ and 3-mJ lasers in full-frame low-bandwidth mode, respectively.
In this paper we present the results of electrical and optical characterization of silicon single-photon avalanche diode (SPAD) development at Voxel Inc. Measurements are made on a 40 x 40 SPAD array test chip with column readout, inpixel integrated active quenching circuit, and pixel enable/disable circuit and ability to control dead time from 37 ns to 1.5 μs. The pixel pitch is 35 micrometers and includes three different SPADs with active-area diameters of 8 micrometers, 10 micrometers, and 14 micrometers. The realized SPADs have a breakdown voltage of 22.5 V with peak-to-peak variation of less than 36 mV across the array. At room temperature, with 10% over-bias the DCR is only 0.22 Hz/μm<sup>2</sup>. The SPADs have a sensitive range of 400 – 900 nm, with a peak photon-detection probability of 23% at 500 nm. After-pulsing and crosstalk are within the noise fluctuation of the SPAD and are not significant.
We continue our work on the design and implementation of multi-channel single photon detection systems for highly
sensitive detection of ultra-weak fluorescence signals, for high-performance, multi-lane DNA sequencing instruments.
A fiberized, 32-channel single photon detection (SPD) module based on single photon avalanche diode (SPAD), model
C30902S-DTC, from Perkin Elmer Optoelectronics (PKI) has been designed and implemented. Unavailability of high
performance, large area SPAD arrays and our desire to design high performance photon counting systems drives us to
use individual diodes. Slight modifications in our quenching circuit has doubled the linear range of our system from
1MHz to 2MHz, which is the upper limit for these devices and the maximum saturation count rate has increased to 14
MHz. The detector module comprises of a single board computer PC-104 that enables data visualization, recording,
processing, and transfer. Very low dark count (300-1000 counts/s), robust, efficient, simple data collection and
processing, ease of connectivity to any other application demanding similar requirements and similar performance
results to the best commercially available single photon counting module (SPCM from PKI) are some of the features of
Single photon counting is the most sensitive method for detection of weak signals. However, it has rarely been used in DNA sequencing applications because of its complexity. We present a fiberized 16-channel single photon detection (SPD) module based on avalanche photo diodes (APD). The diodes are cooled at -20 °C and the average dark count is 700 c/s with APD operating at 10V over-voltage. The proposed system uses active quenching based on basic NAND gates and delay integrated circuits (ICs) and is compact in size, robust, easily portable and requires only 120Vac supply for its operation. The fiberization of the diodes using standard components allows the connection of this system to any other system using fibers with FC connectors with up to 400μm core diameters. Comparative performance with superior commercially available photon counting modules has been obtained. The SPD module has been successfully used for fluorescence detection of weak signals in a DNA sequencing instrument and hence the suitability of large active area APD model for DNA sequencing has been verified experimentally.