Patent ID: 7265848

Claim:
A time resolved, nonlinear complex susceptibility measuring apparatus having: a Sagnac type interference light path in which a reference and a probe light to propagate, a light pulse light source for providing a light pulse with which to irradiate a test specimen disposed in the light path and for supplying the Sagnac type interference light path with a light pulse, and a measuring instrument for measuring the intensity of interference light between the reference and probe lights, characterized in that: the reference and probe lights are a pair of polarized lights orthogonal to each other, and the Sagnac type interference light path is a polarized light splitting Sagnac type interference light path, and that the apparatus includes: a direction of polarization converting mechanism for rotating a direction of polarization of the reference and probe lights by an angle of 90° in the polarized light splitting Sagnac type interference light path; a phase difference sweep mechanism for sweeping a phase difference between the reference and probe lights that are output from the polarized light splitting Sagnac type interference light path; and a phase difference compensating mechanism for compensating for a phase difference between the reference and probe lights prior to entry of the light pulse into the polarized light splitting Sagnac type interference light path, whereby a phase difference between the reference and probe lights that are output from the polarized light Sagnac type interference light path is swept and a time resolved, nonlinear complex susceptibility is found from a phase difference sweep interference waveform obtained by measuring the intensity of interference light between the reference and probe lights for each of such phase differences swept.