Canadian Marconi Company

Zhuo-Jun Lu

A characteristic matrix S(j,i) of the system is preformed such that each row j is preformed at a predetermined constant optical path difference. Light from a laser is transmitted through the system at n different laser wavelengths, and a different datum is obtained at each wavelength whereby to obtain a set of n different data. A vector is formed from the n different data, and the characteristic matrix is multiplied by the vector to obtain a correlation vector. The maximum amplitude element of the correlation vector points to the row of a matrix which has the greatest correlation with the obtained data, so that the predetermined optical path difference of that row indicates the phase of the interferometer of the system. In a separate embodiment, the data vector is divided by the characteristic matrix to obtain a second matrix, and the second matrix is used to form an absolute deviation vector. In this method, the minimum value of the vector points to the row of the characteristic matrix which has least absolute deviation from the obtained data than any other one of the rows so that the predetermined optical path difference of this row is indicative of the phase of the interferometer. In a third embodiment, two sets of data are obtained at two different wavelengths whereby to obtain the optical path difference of the interferometer without ambiguity.

Method for measuring optical path difference of an imbalanced

The interferometer is fed by a laser whose wavelength is modulated. The frequency of the optical fringes generated by modulating the wavelength of the laser are measured. Preferably, the measurement of the frequency is carried out by counting pulses. A system for carrying out the method includes a pulse counter circuit.

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Pierrefonds, Canada

Zhuo-Jun Lu