Quasi-equal-path electronic speckle pattern interferometric system.

Limitations of a quasi-equal-path electronic speckle pattern interferometric system are discussed. We show that by replacement of the reference glass plate with a plano-concave lens the quasi-equal-path electronic speckle pattern interferometric system can be made more versatile. An arrangement to reduce the aberration in the reference beam is also presented.

Quasi-equal-path electronic speckle pattern interferometric system.

A quasi-equal-path electronic speckle pattern interferometric system that uses the polarization property of a diffusing object is presented. The fringe pattern is extremely stable with high visibility. Phase stepping in this arrangement is accomplished by translating the glass plate used for obtaining the reference beam.

Contrast of the vibration fringes in time-averaged electronic speckle-pattern interferometry: effect of speckle averaging.

This paper presents a detailed investigation of the effect of speckle averaging in electronic speckle-pattern interferometric fringes. The theory states that the constrast of the resultant smoothed fringes increases as the number of frames is increased. It is shown that the contrast of the fringes is optimized with a limited number of superpositions, and further addition results in the reduction of speckle noise with the contrast remaining almost the same.

Tunable self-reference phase conjugate interferometer.

We propose a versatile self-reference phase conjugate interferometer which is based on degenerate four-wave mixing in a photorefractive crystal. A crystal of BaTiO(3) is used to store a wavefront which is compared to its displaced version at a later time. Tunable transverse and longitudinal displacements can be easily given to a wavefront.