Optical sensing of absorbing and inhomogeneous media by AC-reflection near the critical angle

Augusto Garcia-Valenzuela; M. Pena-Gomar

doi:10.1117/12.361263

2 September 1999 Optical sensing of absorbing and inhomogeneous media by AC-reflection near the critical angle

Augusto Garcia-Valenzuela, M. Pena-Gomar

Proceedings Volume 3878, Miniaturized Systems with Micro-Optics and MEMS; (1999) https://doi.org/10.1117/12.361263
Event: Symposium on Micromachining and Microfabrication, 1999, Santa Clara, CA, United States

Abstract

We discuss an optical reflection technique to sense very small variations of the refractive index that can be applied to absorbing and non-homogeneous media. The technique offers the possibility of being integrated, using MOEMS technology into a compact optical probe for a variety of applications, and may be the core for a new class of generic sensors. It consists of AC-modulating the angle of incidence near the critical angle and measuring the reflectivity variations. This technique may be a useful alternative to design a refractive index probe for absorbing and inhomogeneous media were other techniques are strongly limited. The theory necessary to use, develop, and design appropriately these kind of sensors is summarized, and experimental results validating the theory are given. A possible design of a fiber-optic probe based on the modulation of the index of refraction of a micro-prism through the elasto-optic effect is given.

Citation Download Citation

Augusto Garcia-Valenzuela and M. Pena-Gomar "Optical sensing of absorbing and inhomogeneous media by AC-reflection near the critical angle", Proc. SPIE 3878, Miniaturized Systems with Micro-Optics and MEMS, (2 September 1999); https://doi.org/10.1117/12.361263

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