TABLE OF CONTENTS While liquid crystal materials have been implemented as variable phase shifters and polarization modulators in polarization microscopy, liquid crystal spatial light modulators (SLM) have been investigated in a variety of other imaging and microscopy applications. Because liquid crystal spatial light modulators are the primary component of a liquid crystal display, the technology of these devices is both mature and readily commercially available. Alternative applications of liquid crystal spatial light modulators in techniques such as phase contrast microscopy, scanning microscopy, and adaptive optics are discussed.
Much like polarization microscopy, phase contrast microscopy systems are employed for viewing samples with little absorptive contrast, such as biological specimens. Unlike polarization microscopy, birefringence is not required for contrast generation in phase contrast microscopy, rather just a variation in refractive index. In a phase contrast microscope, differences in refractive index are detected by their manifestation as diffraction. The configuration is similar to a bright field microscope except that (1) a phase plate is placed after the objective lens to generate a spatially dependent phase difference and (2) the sample is illuminated using oblique light through an annulus in the light delivery system. Light unperturbed during propagation through the specimen will encounter the phase plate at one phase delay, while diffracted light will encounter the phase plate at a different phase delay, generating a phase shift between these two beams, usually 90 . As the two...
