Toward a 3-D Camera Based on Single Photon Avalanche Diodes

Abstract

A three-dimensional (3-D) imager is presented, capable of computing the depth map as well as the intensity scale of a given scene. The heart of the system is a two-dimensional array of single photon avalanche diodes fabricated in standard CMOS technology. The diodes exhibit low-noise equivalent-power high-dynamic range, and superior linearity. The 3-D imager achieves submillimetric precision at a depth-of-field of a few meters. This precision was achieved by averaging over 10 000 measurements. The imager operates using a standard laser source pulsed at 50 MHz with 40-mW peak power and requires no mechanical scanning mechanisms or expensive optical equipment.

System Tradeoffs in Gamma-Ray Detection Utilizing SPAD Arrays and Scintillators

“…Standard SPAD jitters range from roughly 100 ps FWHM in fully digital SPAD TDC arrays to several hundred picoseconds in silicon photo-multipliers, though jitters as small as 70 ps sigma have been measured in SiPMs [9]- [12]. Light detection efficiencies range from over 25% for optimized silicon photo-multipliers with high fill factors and PDPs to under 5% in some modern SPAD TDC arrays with low fill factors [11], [13] . When coupled to a LYSO crystal that gives off roughly 14 500 scintillation photons per 511 keV gamma-ray, the number of primary photoelectrons would range from roughly 3600 for a detector with a light detection efficiency of 25% to under 150 for a detector with a light detection efficiency of 1% [14].…”

A 4μs integration time imager based on CMOS single photon avalanche diode technology

“…10 illustrates the optical response of a typical pixel to a variable illumination measured with an integration time of 1 s. The sensor was tested with a homogenous illumination using a monochromator whose wavelength was set to 635 nm. At a high intensity illumination, when the signal approached 20 mega counts, the SPAD presented a saturation behavior due to the dead time [15]. This point is considered to be the saturation level.…”

“…Due to the absence of readout noise, when the illumination is very low, the signal is only limited by the noise in the dark. Since dark counts respect a Poissonian distribution [15], their average value can be electronically stored for each pixel and removed from the final image. Under this assumption, the temporal noise in the dark is defined as the time varying component of the dark counts, i.e.…”

“…In this case, the TOF of photons originated at a pulsed light source and reflected by an object, must be detected with a precision of a few picoseconds to achieve millimetric depth accuracy [13,14]. This is generally accomplished by averaging a relatively low number of measurements [13,15], thus establishing the potential for high frame rates even in 3D vision.…”

Ad-Hoc Wireless Sensor networks for exploration of solar-system bodies

“…The detection of the back reflected signal from different directions may be performed by a 2-D optical detector in photon-counting mode (SPAD) [21].…”