Why people like the Hybrid PhotoDiode

The Hybrid PhotoDiode (HPD) tube is a new kind of photodetector composed of a vacuum photodiode in which the photocathode is coupled to a PIN diode. It presents peculiarities and performances radically different from those of most existing photon detectors. Because of these characteristics the HPD is generating vast interest in the scientific community and may be useful in a variety of demanding environments.