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Electro-optic sensors made of lasers or photodetectors assemblies can be associated with a window interface. In order to
use these sensors in an avionics application, this interface has to be set on the periphery of the aircraft. This creates
constraints on both the position/access of the associated electronics circuit card and the aircraft fuselage. Using an
optical fiber to guide the light signal to a sensor being situated inside the aircraft where electronics circuit cards are
deployed is an obvious solution that can be readily available. Fiber collimators that adapt to circular TO-can type
window sensors do exist. However, they are bulky, add weight to the sensor and necessitate regular maintenance of the
optical interface since both the sensor window and the collimator end-face are unprotected against contamination. Such
maintenance can be complex since the access to the electronics circuit card, where the sensor is sitting, is usually
difficult. This interface alignment can also be affected by vibrations and mechanical shocks, thus impacting sensor
performances.
As a solution to this problem, we propose a highly-hermetic feedthrough fiber pigtailed circular TO-can package. The
optical element to optical fiber interface being set inside the hermetic package, there is no risk of contamination and
thus, such a component does not require any maintenance. The footprint of these sensors being identical to their window
counterparts, they offer drop-in replacement opportunities. Moreover, we have validated such packaged electro-optic
sensors can be made to operate between -55 to 115°C, sustain 250 temperature cycles, 1500G mechanical shocks,
20Grms random vibrations without any performance degradations. Their water content is much smaller than the 0.5%
limit set by MIL-STD-883, Method 1018. They have also been verified to offer a fiber pigtail strain relief resistance over
400g. Depending on the electronics elements inside these sensors, they can be made to have a MTBF over 50 000h at
100°C.
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