A laser scanning microscope executing intraframe polarization switching of the illumination beam

The polarization of the illumination beam in a beam scanning microscope such as the confocal microscope plays an important role in extracting the orientational information of the molecules in the specimen. In this paper, we present the development of a beam scanning microscope comprising a custom designed optical arrangement to obtain images of the same target with different polarizations of the illumination beam. The optical arrangement, based on a ferroelectric liquid crystal spatial light modulator (FELCSLM), can generate homogeneous as well as non-homogeneous user defined polarization profiles over the cross-sectional area of the illumination beam. Here, we employ a computer generated holography technique and exploit the programmability of the FELCSLM display to considerably reduce the time gap between two successive illuminations of each location of the specimen with two different polarizations. We demonstrate the working of the beam scanning microscope where the polarization profile of the illumination beam is switched at the end of every line scanned, in contrast to a conventional beam scanning microscope where the polarization can be switched at the end of every frame scanned. Preliminary experimental results obtained using a polarization sensitive target confirm the feasibility of the proposed scheme.