Gooch and Housego Plc

Normalair-garrett (holdings) Limited

Cleveland Crystals, Inc.

Jonathan David Ward

Christopher N Pannell

Melvin E Pedinoff

Thomas E Stenger

Owen D Furlong

Ramesh K Shori

Leonard Moore

Stefano Valle

An acousto-optic (AO) device includes an AO crystal having a plurality of faces including a first face and a second face. An input transducer bonded to the first face (top electrode) for receiving a radio frequency (RF) signal and launching bulk acoustic waves (BAWs) configured to interact with an optical beam propagating in the AO crystal, wherein the BAWs are received at least in part by the second face after interacting with the optical beam. The second face has a roughened surface portion over an area of at least (&#x2267;) 50% of an area of the top electrode, and a root mean square (rms) surface roughness&#x2267;1 &#x3bc;m and a surface profile derivable from a Fourier transform which provides at least one a first spatial frequency peak from 1 cycle/mm to 300 cycles/mm or at least one band of spatial frequency peaks from 1 cycle/mm to 300 cycles/mm.

Acoustic absorber having a roughened surface for AO devices

An acousto-optic (AO) frequency shifter includes an anisotropic crystal having an optical axis and an input face, and an acoustic transducer having electrodes affixed to the face for receiving an electrical signal and projecting an acoustic wave into the crystal. The anisotropic crystal is cut relative to the face so that the transducer is at an acoustic angle (&#x3b8;) corresponding to a predetermined angle of incidence (&#x3b8;) of an optical beam to be directed relative to the optic axis of the anisotropic crystal to substantially satisfy the parallel tangents phase matching condition.

High frequency acousto-optic frequency shifter having wide acceptance angle

An acousto-optic modulator includes a (100), (010) or (001) single crystal silicon acousto-optic interaction medium, and at least one transducer for emitting an acoustic wave attached to the single crystal. The transducer has a first electrode layer disposed on one side and a second electrode layer disposed on its other side. The transducer is aligned to the single crystal so that the direction of acoustic propagation in the silicon crystal is substantially along the (100), (010) or (001) direction. A q-switched laser includes a modulator according to the invention.

Silicon acousto-optic modulator

Signal output means (11) responsive to gas flow and particularly suited for use in gas flow indicator apparatus (10), has first and second pressure-datum valves (24, 25) arranged in downstream order in a gas conduit (16), the second pressure-datum valve (25) being arranged to open at a lower pressure difference than the first pressure-datum valve (24). A flueric amplifier (15) has a power jet port (28) connected to the gas conduit (16) on the upstream side of the first pressure-datum valve (24), opposed control pressure ports (26, 27) connected respectively to a chamber (22) formed between the first and second pressure-datum valves (24, 25) and to the gas conduit (16) downstream of the second pressure-datum valve (25), and a vent port (30) also connected to the gas conduit (16) downstream of the second pressure-datum valve (25). A pressure signal output by the flueric amplifier (15) in response to gas flow through the conduit (16) may be used to trigger a visual or audio warning device (14).

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Ilminster, United Kingdom

Jonathan David Ward