Through-focus phase retrieval and its connection to the spatial correlation for propagating fields.

Through-focus phase retrieval methods aim to retrieve the phase of an optical field from its intensity distribution measured at different planes in the focal region. By using the concept of spatial correlation for propagating fields, for both the complex amplitude and the intensity of a field, we can infer which planes are suitable to retrieve the phase and which are not. Our analysis also reveals why all techniques based on measuring the intensity at two Fourier-conjugated planes usually lead to a good reconstruction of the phase. The findings presented in this work are important for aberration characterization of optical systems, adaptive optics and wavefront metrology.

Absolute profile measurement of large moderately flat optical surfaces with high dynamic range.

We present a novel procedure for absolute, highly-accurate profile measurement with high dynamic range for large, moderately flat optical surfaces. The profile is reconstructed from many sub-profiles measured by a small interferometer which is scanned along the specimen under test. Additional angular and lateral distance measurements are used to account for the tilt of the interferometer and its precise lateral location during the measurements. Accurate positioning of the interferometer is not required. The algorithm proposed for the analysis of the data allows systematic errors of the interferometer and height offsets of the scanning stage to be eliminated and it does not reduce the resolution. By utilizing a realistic simulation scenario we show that accuracies in the nanometer range can be reached.

[In vitro studies of allergen activity and the depot effect of semi-depot extracts of grass pollen]. / In-vitro-Untersuchungen zu Allergenaktivität und Depoteffekt von Gräserpollen-Semidepotextrakten.

Employing two different techniques--Al-RAST and RAST inhibition test--we studied semi-depot extracts of grass pollen from six producers. On one hand, we measured the amount of allergens absorbed by Al(OH)3 gel; on the other hand, we determined the quantity of allergens solved in the aqueous phase. Furthermore, we checked up the continuous release of allergens from the depot by means of a simple in vitro model. The six different semi-depot extracts revealed different amounts of allergens in the depot (Al[OH]3) as well as in the aqueous phase. As we measured the continuous release of allergens, we found that all six extracts behaved nearly identically regarding their function as depots, but were different respecting the released amount of allergens. Summing up, it may be said that therapy extracts--analogous to previously examined test extracts--show differences with regard to their allergenic activities but very similar properties in respect to their function as depots.