Abstract

A low-cost humidity and pressure optical sensor, based on the internal reflection phenomenon, is presented. It takes advantage of the phase difference acquired by $s$- and $p$-polarized light undergoing internal reflection to generate an easily detectable minimum in the reflected profile, in a position corresponding to the critical angle. The apparatus presents good sensitivity to relative humidity changes above 70% and a response time below one second. The same device is also capable of measuring changes in pressure and can be used as a vacuum gauge between 1 and 1000 mbar.

© 2014 Optical Society of America

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