Viewing posts tagged SEM
In the last year or two we've been doing a lot of work aimed at replacing photomultiplier tubes (PMTs) in instruments, using avalanche photodiodes (APDs) and silicon photomultipliers (SiPMs). These devices are arrays of single-photon detectors, so they're also known as multi-pixel photon counters (MPPCs). Our main application areas include biomedical instruments such as flow cytometers and microplate readers, which have to measure low light levels very precisely but don't need the ultralow dark current of PMTs. (Follow-on articles will talk about our SiPM work in airborne lidar and SEM cathodoluminescence, as well as on improving the performance of actual PMTs.)
PMTs have been around since the 1930s, and remain the undisputed champs for the very lowest light levels. We love PMTs, but we have to admit that they're delicate and not that easy to use—they tend to be bulky, they need high voltage, and they need regular replacement. Most of all, PMTs are very expensive.
In How We Work, we gave an overview of how we build instruments, from the initial feasibility calculation (or photon budget) to delivery of the first production units.