PHOTOCATHODE Russian patent published in 2009 - IPC H01J40/06 

FIELD: electrics.

SUBSTANCE: invention concerns construction elements of photoelectronic devices, particularly photocathodes on shaped substrates applied as input transducers of electromagnetic emission to electron flow. Photocathode includes light permitting dielectric substrate and thin photoemission layer divided into three parts with different functions. Transduction of light to electrons is performed by photoemission layer parts at the bottom of cells with resistance connection to grid-shaped low-resistance part of photoemission layer at the substrate surface. Resistance of resistive connection is chosen to generate volumetric charge at the cell bottom when given photoemission current from photocathode cell, so that electric field of volumetric charge would return photoelectrons to the cell bottom, thus limiting photo-induced current from the cell. As photocathode consists of several cells collecting current to common low-resistance grid electrode, overexposure of some cells would not affect state of the others, thus enabling photocathode resistance to local overexposure. At low lighting level usual for photoelectronic device operation volumetric charge does not evolve, and photocathode works and normal one. Such photocathodes can be successfully applied in photoelectronic devices of simultaneous monitoring of objects differing in luminance by several orders.

EFFECT: limitation of photocurrent from cell in case of overexposure, photocathode resistance to local overexposure.

4 cl, 5 dwg