Quantification of critical alignment parameters for a rotationally-shearing interferometer employing exact ray trace

Abstract

A rotationally-shearing interferometer (RSI) is sensitive to asymmetries in wave fronts. The rotational system, composed of a Dove prism, provides an adjustable sensitivity to the RSI, which is most desirable for asphericity measurements and extra-solar planet detection. We are interested in determining the magnitude of critical engineering parameters that ensure a performance better than /10 for the RSI. Previously, we determined that, when the manufacturing tolerance of the angles of a Dove prism is maintained within AE0.35 arcsec, the maximum wave-front deviation is less than /10 (at 633 nm). In this work, we study the angular and the change-induced deviations caused by the positioning of the rotational system. We determine, employing exact ray trace, the positioning tolerances and the resolution of the fine mirror movements needed to satisfy a maximum wave-front deviation of /10 in the RSI. This analysis shows that the compensating element of the RSI provides a 0.7 arcsec window, wherein the maximum OPD remains below /10. Moreover, the positioning tolerance in the RSI must lie within AE0.33 arcsec. The results suggest the use of piezoelectric actuators to control prism and mirror mounts to ensure the desired performance.

Photothermal deflection of laser beam as means to characterize thermal properties of biological tissue: numerical study

“…Different proposals for ray trace analysis have been published [15][16][17]. All of them may be used to determine the angle deflection of laser beam.…”