true signal from background noise. ‘The beauty of single photons is that you can have a highly sensitive return,’ he underlined. ‘You can also have a very high time resolution, pretty much better than any analogue non photon counting system, since this makes the signal large compared to the noise.’ Temporal resolution can go down to less than 100 picoseconds, which enables clear, concentrated signal detection against the background, Buller said. It is central to distinguishing photons that may be returning from obscured objects, such as lower levels of tree canopy. Some examples of existing single photon detectors are silicon-based electron multiplying charge coupled devices (EMCCDs) available from UK-based
“Typical lidars might run at a few tens of hertz. In photon counting, it’s not unusual to be running at megahertz or tens of megahertz”
www.electrooptics.com | @electrooptics
www.lasercomponents.co.uk
Teledyne e2v. They are ‘widely used in the most sensitive applications in life science facilities and more recently in quantum technology research’, said Cliff Weatherup, Teledyne e2v’s strategic technology manager. ‘The wavelength range of silicon extends from the ultraviolet to the near infrared with a cut-off at 1,064nm. ‘There is a lot of interest in extending
this detection capability out to the short- wave infrared and into the medium wave where there are a lot of performance benefits and some significant synergies with laser sources,’ Weatherup continued. ‘Teledyne has an ongoing interest in extending the capabilities in its current array detectors out to these longer wavelengths to drive technology advances in its existing markets and help extend our reach in new markets.’
The shape of sensing to come Time correlated single photon counting (TCSPC) is an increasingly well- established technique in lidar added Robert Lamb, chief technical officer, electro optics, at Leonardo in Edinburgh. This statistical sampling method records
SINGLE PHOTON COUNTER
g
▪ Fast 350 ps timing resolution ▪ High QE over 70 % ▪ Low dark count rate <10 cps ▪ Extended blue, extended NIR
Geiger Mode APD-Modules
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