Journal of the Optical Society of America/
~ researchers have invented an optical on-off switch to replace electrical wiring on airplanes with fiber optics for controlling elevators, rudders, and other flight-critical elements
~ new optical device is an on-off switch which senses press of a button from a pilot
~ a system based on a single optical fiber could potentially sense presses from hundreds of buttons simultaneously
~ crucial component is a fiber Fabry-Perot interferometer (FFPI) which consists of two parallel mirrors
~ when white light passes through mirrors, some of it bounces between mirrors, and some passes through
~ these light waves combine or "interfere" to produce a pattern
~ interference pattern changes if distance between the mirrors changes
~ a small plank-like object cantilever is bonded to interferometer and cantilever is attached to a switch
~ pressing switch creates a force on cantilever, which causes it to bend, changing spacing between mirrors and thereby altering interference pattern
~ altered interference pattern provides a signal to indicate that switch has been pressed
~ this information can be transmitted optically to desired part of airplane
~ a network of other interferometers and lasers filters out fluctuations in temperature and other disturbances so that only press of button registers as a valid signal
~ a fiber-optics system is lightweight and does not take up much room and it is immune from lightning and electromagnetic interference
~ it also is a safer alternative for planes as it is not susceptible to causing fires
~ fiber-optic approach is intended for both military and commercial aircraft
~ it could either be incorporated into new designs or retrofitted into existing aircraft
~ voice communications equipment in newer aircraft is already fiber-optics based
~ integrating other aircraft instrumentation into a single optics package could save weight, space, fuel, and construction costs on future aircraft