X-RAY IMAGE CONVERTER TUBE Russian patent published in 1994 - IPC

FIELD: electronic instrument engineering. SUBSTANCE: X-ray image converter tube has envelope provided with entrance window. There are X-ray luminescent screen and photocathode inside the envelope; the photocathode is formed onto internal surface of the screen. There are electrostatic focusing electrodes, anode and output cathode-luminescent screen inside the envelope as well. Moreover, hole of the anode is covered with conducting grid, made in form of spherical segment, which has radius of curvature being equal to R_s. The segment is aligned with photocathode at distance L_cat from its center. Aperture diaphragm is mounted in the surface of electron beam minimal cross-section, between spherical segment and output screen. The diaphragm is mounted at distance L_cr from center of photocathode. Relations for determining R_s, L_cat and L_cr are given. Distance between photocathode and anode is reduced by 1.6 times in X-ray image converter tube, contrast is increased 2-3 times. EFFECT: improved efficiency. 2 dwg