Exalos has developed superluminescent LED (SLED) modules that are less sensitive to wavelength shifts induced by temperature or ageing, for more accurate and reliable inertial navigation systems (writes Nick Flaherty). A key application for SLEDs is in navigation systems, such as avionics, aerospace, sea, terrestrial and subsurface, that use fibre optic gyroscopes (FOGs) to make precise rotation measurements. FOGs measure the phase shift of optical radiation propagating along a fibre optic coil when it rotates around the winding axis. The new generation of SLED modules use frequencies from 400 to 1700 nm to improve their wavelength stability by a factor of four compared with conventional devices. They are packaged in cooled 14-pin dual inline and Butterfly packages, cooled and uncooled five-pin Butterfly packages and low-cost uncooled TOSA and TO-56 packages. The basic components of a FOG are a light source, a singlemode fibre coil, an optical coupler, a modulator and a detector. Light from the source is fed into the fibre in counter-propagating directions using the coupler. When the fibre coil is at rest, the two light waves interfere constructively at the detector, and a maximum signal is produced at the modulator. When the coil rotates, the waves take different optical path lengths that depend on the rate of rotation. The phase difference between the waves varies the intensity at the detector and provides information on the rate of rotation. SLED-based gyroscopes rely on the wide bandwidth of the source to reduce both the large Kerr-induced drift and the high coherent backscattering noise along the fibre. Navigation SLEDS add stability Using a superluminescent LED in a fibre optic gyroscope +1 (503) 434-6845 | www.nwuav.com Supporting The War Fighter Since 2005 with Aviation Grade Propulsion Systems Northwest UAV AVIATIONGRADE AMERICAN MADE NW-230 Heavy-Fuel Engine NW-44 FUEL INJECTED HEAVY-FUEL ENGINE 34-68 Kg UAS 18-34 Kg UAS NW-88 TWIN-CYLINDER HEAVY-FUEL ENGINE DEFENSE CONTRACT AUDIT AGENCY COMPLIANT VISIT US AT Designed for Group III Unmanned Aircraft in the 90-160 kg range. With an emphasis on high TBO, minimal maintenance cycles and high endurance with minimal fuel burn. • MADE IN THE USA • Purpose-built for Heavy-Fuel APRIL 22-25, 2024 Booth #4437 APRIL 8-10, 2024 Booth #3317
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