New Sensing Techniques Using Spatio-temporal Dynamics of Phase Singularities in Scattered Random Optical Fields : A Basic Research

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The purpose of this research project is to establish the basis of a new sensing technique for high-precision displacement measurement based on spatio-temporal dynamics of phase singularities in random optical fields. Because the proposed technique uses phase singularities as position markers imbedded on the surface of an object and traces the movement of the individual phase singularities, it can measure non-uniform displacement fields including rotation and scale changes, which has not been possible by conventional correlation techniques. The main achievements are summarized as in the following :1.The generation of the pseudo-phase singularities from the complex analytic signal of a random pattern has been proposed, which enabled the use of pseudo-phase information without recourse to interferometry.2.Displacement measurement with nanometric spatial resolution has been achieved by use of the phase singularities in the pseudo-phase distribution.3.Measurement of large non-uniform displacements and deformations has been successfully demonstrated by use of the information about the local structure of phase singularities.4.Phase singularities in a coherence function have been observed for the first time by experiment.Integrating all the above results, a new displacement-sensing system was developed that makes use of the phase singularities in the analytic signal of a random texture of the object and applied to the measurement of biological samples.