As an improvement of the intensity correlation used widely in conventional electronic speckle photography, we propose a new technique for displacement measurement based on correlating Stokes-like parameters derivatives for transformed speckle patterns. The method is based on a Riesz transform of the intensity speckle pattern, which converts the original real-valued signal into a complex signal. In closest analogy to the polarisation of a vector wave, the Stokes-like vector constructed from the spatial derivative of the generated complex signal has been applied for correlation. Experimental results are presented that demonstrate the validity and advantage of the proposed pseudo-Stokes vector correlation technique over conventional intensity correlation technique.

As an alternative to correlation-based techniques widely used in conventional speckle metrology, we propose a new technique that makes use of phase singularities in the complex analytic signal of a speckle pattern as indicators of local speckle displacements. The complex analytic signal is generated by vortex filtering the speckle pattern. Experimental results are presented that demonstrate the validity and the performance of the proposed optical vortex metrology with nano-scale resolution.

Ishijima, R, Wang, W, Qiao, Y, Yokozeki, T, Honda, D, Matsuda, A, Hanson, SG, Miyamoto, Y & Takeda, M 2006, Optical metrology using the spatial structures of phase singularities in the analytic signal representation of a random pattern, and its application to biological kinematic analysis (in Japanese, abstract in English). in Proceedings. Optical Society of Japan, Tokyo, pp. 448-449, Optics and Photonics Japan 2006, Tokyo, Japan, 08/11/2006 … Optical metrology using the spatial structures of phase singularities in the analytic signal representation of a random pattern, and its application to biological kinematic analysis (in Japanese, abstract in English). / Ishijima, R.; Wang, W.; Qiao, Y.; Yokozeki, T.; Honda, D.; Matsuda, A.; Hanson, Steen Grüner; Miyamoto, Y.; Takeda, M … Proceedings. Tokyo : Optical Society of Japan, 2006. p. 448-449.