In microscopy, several different phase contrast methods (e.g. Zernike contrast, differential interference contrast) have been developed to image phase objects. For these methods specialized microscopic equipment (modified microscope objectives, filters, etc.) is needed. The static elements within such microscopes are a trade-off, because phase contrast imaging depends strongly on the object and the information to be visualized. We show results of an implementation of many different phase contrast methods using a high resolution phase-only spatial light modulator (SLM) in the pupil plane. All implemented methods are realized by software. Therefore, it is not only feasible to change the different phase contrast methods in real time, but it is also possible to optimize the parameters. Images obtained from different settings are combined digitally to improve the final image quality. Furthermore, completely new phase contrast filters can be tested easily because the phase of each pixel can be changed arbitrarily. We use this method to implement a new phase contrast filter that is obtained by combining a focused and a defocused point spread function. We will present theoretical as well as experimental results of this vertical differential interference contrast filter.
© 2011 OSA/SPIEPDF Article