Manufacture of an optical effector using silicon micro-machining

Using a complex micro-machined structure a novel optical-to-fluid pressure converter has been developed. The device offers immunity from electromagnetic interference and the potential for intrinsic safety. The effector, an improved version of a previous device, has been further miniaturized and fully micro-machined from silicon and glass. The device operates when light enters a sealed air-filled cell, formed within a silicon wafer, and is converted to heat by an absorber. The associated rise in temperature increases the pressure inside the cell and forces a diaphragm to move. The diaphragm movement is detected by a change in the back pressure of an impinging jet of fluid, which can be either pneumatic or hydraulic. The response time of the device, of the order of tens of milliseconds, has been further reduced as a result of miniaturization. This paper outlines the manufacturing technique and presents selected experimental test results.