One-shot phase stepping with a pulsed laser and modulation of polarization: application to speckle interferometry.

For applications involving time varying optical phase distributions, fast cameras and/or pulsed lasers have to be used. To apply phase-shifting interferometry techniques (PSI) as well, single shot capture is required. Among others, modulation of polarization and phase grating interferometry is a possible technique to be considered. In this paper, a report about the use of this technique based on a double pulse laser system is presented. Single-pulse and twin-pulse operations are considered both in optical interferometers as well as in ESPI systems (mainly in subtraction mode). In ESPI a reduction of the degree of polarization appears due to scattering, so some measures have to be taken to prevent such deletereous effect. To show the feasibility of the proposed variants some experimental results are presented.

Only one fitting for bironchigrams.

We present an algorithm that uses a square grid in a Ronchi test. We assume that the point coordinates of this pattern (termed a bironchigram) are affected by Gaussian errors. To calculate the optical path difference, we apply only one nonlinear least-squares fit to the dot coordinates. The relevant equations are deduced, and experimental results are shown.

Aberration extraction in the hartmann test by use of spatial filters.

Using a computer, we generated a set of filters to aid in the retrieval of aberration functions from Hartmanngrams. These filters consist of discrete two-dimensional data points, like the Hartmanngrams themselves, and are orthogonalized by the Gram-Schmidt procedure. The aberration coefficients are obtained by calculation of the scalar product of the Hartmanngram and each orthogonal filter.