초록 ▼

Broadband energy incident on a transducer having partially or fully reflective surfaces separated by a gap which is greater than the coherence length of the broadband energy but smaller than one-half a coherence length of a band of energy within said broadband energy causes a portion of the spectral

Broadband energy incident on a transducer having partially or fully reflective surfaces separated by a gap which is greater than the coherence length of the broadband energy but smaller than one-half a coherence length of a band of energy within said broadband energy causes a portion of the spectral content of the broadband energy corresponding to a coherence length greater than twice the gap length to exhibit interference effects while the average power of the broadband energy remains unaffected. Splitting energy reflected from the transducer into two beams which are filtered at preferably similar center frequencies but with different pass bands yields beams which are radically different in sensitivity to changes in gap length. Analyzing the beams to derive a ratio of powers (since source intensity and fiber attenuation in a common fiber are thus self-cancelling) allows high accuracy and high resolution absolute measurement of temperature, pressure or strain. Effects of any of these physical parameters which are not of interest in a measurement can be fully compensated or made arbitrarily insignificant in a simple transducer structure of extremely small size. Use of broadband energy permits measurement over greater lengths of optical fiber.

대표청구항 ▼

[ Having thus described my invention, what I claim as new and desire to secure by Letters Patent is as follows:] [1.] An optical fiber measurement system includinga source of broadband energy,an interferometric transducer means for producing periodic intensity variation with continuous change in mea

[ Having thus described my invention, what I claim as new and desire to secure by Letters Patent is as follows:] [1.] An optical fiber measurement system includinga source of broadband energy,an interferometric transducer means for producing periodic intensity variation with continuous change in measurand by a path length difference,a band-pass filter having a pass band smaller than a spectral content of said broadband energy and corresponding to a coherence length greater than said path length difference, andmeans for determining a ratio of energy of a portion of said broadband energy received from said interferometric transducer means having a coherence length less than said path length difference to energy of another portion of said broad band energy received by said transducer having a coherence length greater than said path length difference.