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

Next Wednesday 18th June, Professor Silvano Donati is going to provide a technical session in CD6. Silvano Donati of the Department of Electronics University of Pavia (Italy) is IEEE and USA Life Fellow and a leading researcher in the field of electro-optical sensors and Self-Mixing Interferometry.

The technical session entitled "Self-Mixing Interferometry: Universal Yardstick to Measure Almost Everything" will be held at CD6 headquarters in the UPC Campus in 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.