Consiglio Nazionale Delle Ricerche

Anna G Mignani

Giuliano Conforti

Riccardo Falciai

Andrea A Mencaglia

Mario Brenci

Massimo Brenci

Cosimo Trono

Anna M Verga-Scheggi

Mauro Bacci

A description is given of a sensor for measuring the UV fraction of a radiation, comprising a photochromic transducer consisting of a photochromic material ( ) with characteristics of reversible photochromism, whose absorbance varies as a function of the UV fraction of the radiation (R) incident on the photochromic material. An optical path ( ) is provided to guide a light signal through said photochromic material and collect a return light signal, whose value is proportional to the level of absorbance of the photochromic material.

Fiber optic sensor with photochromic transducer, and corresponding method

Vibrations of a body are measured by attaching a vibrating element to the body, directing a beam of electromagnetic energy onto the vibrating element and collecting reflected electromagnetic energy from the vibrating element. The magnitude of the reflected electromagnetic energy is processed to determine vibration and/or temperature of the body. The magnitude of the reflected light is preferably a function of second degree of the position of said vibrating element. Processing said magnitude of reflected electromagnetic energy is preferably done by a Fourier series up to a second harmonic.

Fiber-optic vibration sensor

The sensor comprises a vibrating sheet (1), mechanically connected to the body (5A) to be analyzed, and an optical triangulation recording system for recording the displacements of the movable part of the sheet, in particular the free end (1B) opposite to that which is restrained. The recording system comprises two optical fibers (7, 9) ending in microlenses (10, 12) having optical axes mutually inclined and converging in the movable part (1B) of the sheet.

An optical fiber temperature thermometer uses a thermochromic substance having optical absorption peaks which vary with temperature within a first waveband, and having substantially constant absorption with temperature in a second waveband. The radiation employed is in a wide band to include the first and second wavebands, and the radiation, reflected and attenuated as a result of the passage through the thermochromic substance, is split into two selected beams and filtered in narrow band pass filters for the first and second wavebands, to supply optical signals to respective detectors whose outputs are divided to produce a ratio signal representative of the temperature. The sensor is sufficiently compact for biomedical use, and, being unaffected by electromagnetic fields, is useful in regions of high tension or in microwave heating.

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Florence, Italy

Anna G Mignani