Electron-optical terminal image device based on a cold cathode

An image converter device for UV or X-ray images, including an airtight vacuum envelope comprising:

• (a) a multilayered photocathode structure, said structure including a non-conducting substrate substantially transparent to UV or X-ray radiation laminated with the following thin layers in sequence:
• (i) a first conductive layer serving as a ground voltage inducing electrode which is substantially transparent to the UV or X-ray radiation;
• (ii) an insulator film which is substantially transparent to the UV or X-ray radiation;
• (iii) a semi-conductor film;
• and
• (iv) a second conductive layer serving as a cover electrode including a multiplicity of electron-ejecting cathode spots each having a thickness of no more than 40 nm for allowing a passage of electrons;
• and
• (b) an anode structure including a fluorescent screen positioned parallel to said cold cathode structure and being separated from said photo-cathode structure by an electron acceleration space.