Actualitat

Self-Mixing Interferometry: a Universal Yardstick to Measure Almost Everything

El proper dimecres 18 de Juny el professor Silvano Donati impartirà una sessió tècnica al CD6. Silvano Donati del Department of Electronics University of Pavia (Itàlia) és IEEE i OSA Life Fellow i una figura mundial en el món dels sensors electro-òptics i en particular de la interferometria de self-mixing.

La sessió tècnica titulada “Self-Mixing Interferometry: a Universal Yardstick to Measure Almost Everything” tindrà lloc a l'edifici del CD6 al Campus de la UPC a Terrassa.

Abstact: In this talk, we start with a theoretical introduction to mutual- and self-coupling phenomena in laser oscillator, and then describe in details the principle of operation of self-mixing interferometer, a new coherent configuration for the measurement of dimensional and kinematic quantities such as: displacement, distance, vibration amplitude, thickness, and angle, and also physical quantities like: coupling factors, line width, alfa-facto index of refraction. In the measurement arrangement, the laser
undergoes self-injection at weak level, leading to an amplitude and frequency modulation driven by external optical path length. Then we will describe the developments of a displacement-measuring instrument, first by using the up/down counting of mode hops, then extending the principle of measurement to the case of a diffuse target, reflecting back a field affected by the speckle-pattern statistics. Third, we will report on the successful implementation of two-channel (or, referenced) vibrometer, based on analogue processing of the self-mix signal, in which the speckle-related amplitude errors are removed thanks to a servo-loop concept, and the instrument is capable of true differential operation, on diffuse surface, like a normal optical interferometer operates on legs ending
with reflective surfaces. A survey of perfomance achieved in different design will conclude the talk.