Method of adjusting a video microscope system incorporating polarization

Abstract

A method is disclosed for adjusting a polarizing or interference type video microscope system so as to achieve significant improvement in resolution, contrast, speed of recording, image fidelity and visibility of fine detail, the video microscope system including (1) a polarizing or interference type microscope having an iris diaphragm and a compensator and (2) a video camera having an adjustable gain control circuit and an adjustable DC restoration circuit. The method involves lowering the gain and the clamp level of the DC restoration circuit in the video camera to a minimum, then adjusting the microscope for optimum optical imaging conditions, these conditions including partly closing the iris diaphragm and setting the compensator for .+-. approximately the same bias retardation as the specimin (i.e. .lambda./100-.lambda./50), then opening the diaphragm to the maximal working aperture of the microscope objective and setting the compensator at a bias retardation of around .lambda./9 to .lambda./4, depending on source brightness, and then raising both the gain and the clamp level of the DC restoration circuit to form an image of favorable visual contrast on the video monitor. The invention is based on the discovery that by setting the compensator of the microscope at bias retardations of around .lambda./9 to .lambda./4 rather than bias retardations of around .lambda./100 to .lambda./50, as in conventional high extinction techniques, the difference between the background brightness and specimen brightness can be increased and that even though a specimen examined at such higher bias retardations may not be visually perceptible when viewed directly though the microscope because of the high background level, by increasing the gain and raising the clamp level of the DC restoration circuit the contrast can be improved such that the image may be made visually perceptible on the video monitor. Using a polarization type microscope, the method may be employed, for example, in observing birefringence in living cells, such as in the motile reticulopodial network of Allogromia laticollaris and using a differential interference contrast microscope the method may be employed, for example, in analyzing microtubule retated motility in the reticulopodial network of Allogromia laticollaris. The invention eliminates the need for using polarizing rectifiers.