Displacement measurement with intracavity interferometry

conference paper

English

We present a measuring technique for displacement and position sensing over a limited range with detection of standingwave pattern inside of a passive Fabry-Perot cavity. The concept considers locking of the laser optical frequency and the length of theFabry-Perot cavity in resonance. Fixing the length of the cavity to e.g. a highly stable mechanical reference allows to stabilize wavelength of the laser in air and thus to eliminate especially the faster fluctuations of refractive index of air due to air flow and inhomogeneities. Sensing of the interference maxima and minima within the cavity along the beam axis has been tested and proven with a low loss photoresistive photodetector based on a thin polycrystalline silicon layer. Reduction of losses wasachieved thanks to a design as an optimized set of interference layers acting as an antireflection coating. The principle is demonstrated on an experimental setup.

antireflective coatings; Fabry Perot interferometers; interferometry; lasers; photodetectors; refractive index; silicon

LAZAR, J.; HOLÁ, M.; FEJFAR, A.; STUCHLÍK, J.; KOČKA, J.; OULEHLA, J.; ČÍP, O.

1. 5. 2014

0277-786X

Proceedings of SPIE

United States of America

913210:1

6

6