Patent ID: 7638745

Claim:
A device for use in measuring photon energy, the device comprising: at least one pixel unit comprising at least a Photocathode exposed to electromagnetic radiation to emit electrons in response to absorbed photons, and an Anode electrode; a control unit comprising a voltage supply to at least one electrode and configured for scanning a spectrum of energies of electrons emitted from the Photocathode electrode said scanning comprising varying a retarding electric field in a vicinity of the Photocathode thereby inducing a change in an electric current from the Photocathode to the Anode by selectively preventing arrival to the Anode of electrons having energies below a certain given energy value corresponding to the applied retarding field, the spectrum of electron energies correlating with energy distribution of photons incident onto the Photocathode and causing emission of said electrons, a change in the electric current being therefore indicative of the spectrum of photon energies incident on the Photocathode.