Flexible Adaptive Phase Contrast Methods Using a Spatial Light Modulator

In microscopy, several different phase contrast methods (like Zernike contrast or differential interference contrast) have been developed to image phase objects. For all those methods different microscopic equipment like special microscope objectives or filters are needed. Each of those methods with its static elements represents a trade-off, as ideal phase contrast imaging depends strongly on the object. A variation of different methods is difficult and expensive. Therefore we use a spatial phase-only modulator in the pupil plane for phase contrast filtering. By changing the filter via software, we can easily adapt the filter to the object. Furthermore, it is possible to vary the different methods and their parameters in real time. As there are no mechanical changes, it is possible to easily combine those pictures digitally to benefit from the advantages of different methods and to improve the image quality. Results of different adaptive phase contrast methods (adaptive Zernike, quantitative phase contrast, DIC) are presented. Two new phase contrast methods (modified DIC and a digital combination of different methods) show the high flexibility and potential of the method.