Abstract: A photocathode comprises a substrate in which a cavity is formed and a film of material disposed on the substrate. The film of material comprises an electron emitting surface configured to emit electrons when illuminated by a beam of radiation. The electron emitting surface is on an opposite side of the film of material from the cavity.

Abstract: A ring laser gyroscope includes active cavity containing gain medium, first reflective surfaces coupled to active cavity, medium exciter to excite gain medium, second reflective surfaces coupled to first passive cavity, and third reflective surfaces coupled to second passive cavity. Excited gain medium induces first and second laser fields within active cavity. First plurality of reflective surfaces includes first, second, and third reflective surfaces that reflect light within active cavity. Second plurality of reflective surfaces includes first, fourth, and fifth reflective surfaces that reflect light within first passive cavity. Third plurality of reflective surfaces includes fourth, sixth, and seventh reflective surfaces that reflect light within second passive cavity. First and fourth reflective surfaces are partially transmissive such that they both transmit and reflect light.

Abstract: A semiconductor ring laser gyro includes: a semiconductor laser for emitting light from each end of the gyro; at least one reflection prism comprising a plurality of reflection surfaces for forming an optical circuit, the at least one reflection prism adapted to receive and internally reflect the light emitted from the semiconductor laser; a transmissive mirror disposed at one of the plurality of reflection surfaces of the at least one reflection prism and adapted to transmit part of the light traveling clockwise and part of the light traveling counterclockwise through the optical circuit; and a beam multiplexing prism for multiplexing the light transmitted through the transmissive mirror.

Abstract: A photodiode is formed with an integral mask so as to be able to undesirable light. By forming the mask directly on the photodiode instead of etching the mask on a cover, or placing a mask on the cover, misalignment problems can be avoided.