Gec Ferranti Defence Systems Limited

Gec-marconi Avionics Holdings Limited

Roger Hill

John Nuttall

Roger K Tolfree

An apparatus and method for depositing multiple layer, thin optical films onto a substrate and an optical filter made thereby. The apparatus includes a vacuum chamber; moving means for moving the substrate between regions of the vacuum chamber; material depositing means within each region for depositing a film of material on the substrate; a reactive substance source for introducing a reactive substance into each region so as to react with the material as it is deposited in that region; and control means for controlling the degree of such reaction in one region relative to the other, to obtain desired stoichiometry in the deposited materials. The method includes moving the substrate between regions; depositing different materials on the substrate in respective regions; introducing a reactive substance into each region so as to react with the material as it is deposited in that region; and controlling degree of reaction in one region relative to that in another region to obtain a desired stoichiometry in the deposited materials.

Depositing different materials on a substrate

The gyroscope had a closed optical path (10) defined by four reflecting surfaces (11, 12, 13, 14). Counter-rotating beams of radiation circulating around the closed path are produced by a gaseous active lasing medium executed over a gain region (15) to produce a discharge in the gas. A reciprocal dispersion element (18) is located in the optical path and a solenoid (23) is wound around part of the gain region to produce a magnetic field over that region. One of the reflecting surfaces (14) is a partially transmitting mirror which passes a small proportion of the radiation incident upon it, and detectors (19, 20) detect radiation in each counter-rotating beams passing through the mirror (14). The alternating current components of the outputs of the detectors are used to control a control circuit (22) so as to control the magnetic field produced by the solenoid (23).

Multi-oscillator ring laser gyroscope with improved stabilization

A closed path (14) around which two beams of laser radiation may pass in opposite directions is formed in a block (10) of material and is defined by at least three mirrors (11, 12 13). One of these mirrors (11) is partially transmissive of laser radiation in each beam and has detector means (17, 18) associated with it to derive electrical signals dependent upon the rotational forces acting on the gyroscope about an axis 19. A second mirror (12) is totally reflecting and is associated with a transducer (20) which continuously moves the mirror. Second detector means (21) is responsive to laser radiation in the two beams to derive alternating-current signals to control the transducer (20). Control means (22) respond to the direct-current component of the output of the second detector means (21) to maintain the intensity of the laser beams at a constant value.

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Midlothian, United Kingdom

Roger Hill