Displacement sensor made by potassium diffusion on glass

A displacement sensor using a double Michelson interferometer integrated on glass is presented. The design employs only Y junctions and the single-mode waveguides are made by potassium diffusion. Conventional lenses and flat mirrors are compared to gradient index lenses for collimating and reflecting the sensing beam. The reflection from the moving mirror and the contrast of the interference signals are studied as a function of the distance from the sensor to the mirror. The resolution is improved from 20 to 0.7 nm when an optical isolator is connected to the laser diode.<
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