A photorefractive Bi 12 TiO 20 (BTO) crystal is exposed with high intensity pulsed-laser beams 532 nm (the average intensity of the laser was 110 mW/cm 2 , the average intensity per pulse was 2 MW/cm 2 ), and the photo-induced dynamics of the absorption between 480 and 900 nm are studied and explained by two long-lived energy levels in the forbidden band. The relaxation times of the long-lived energy levels are experimentally found to be 10 4 and 10 5 s. The hysteresis character of the absorption coefficient is discussed.

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We demonstrate in experiment that the resolution of a conventional light microscope can be enhanced by 26% with the help of an image inverting interferometer. In order to prove this statement, we measured the point spread function of the system as well as the resolution of two-point objects. Additionally, the contrast transmission function of the interferometric setup was measured and compared to the results gained with a conventional wide-field microscope. Using the interferometric system, the spatial frequencies near the cutoff-frequency were far better transmitted than by the conventional microscope. Finally, we demonstrate the improved resolution with the help of images of two-dimensional structures.

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JNDs were lower for coma than for astigmatism and trefoil, depending on the magnitude of other residual aberrations, and showed large variations among subjects. Thus, the decision to correct more pronounced aberrations (eg, by wavefront-guided LASIK) should not depend on wavefront measurement results alone. A staircase procedure for determination of JNDs provides repeatable results.