Laser dark-field microscope: investigation of the motility of submicroscopic structures

摘要

Some years ago we have built a dark-field microscope based on a catadioptric objective used as a dark-field condenser (Krol et al. 1990, Eur. Biophys. J. 19: 93-99). The apparatus allowed to measure small (tens of nm) transverse displacements of light-scattering micro-objects, such as cell margins or intracellular particles. The principle of apparatus was the registration of the change in the intensity of light scattered from a moving structure that goes in or out the small scattering area (0.5 250L?.5 μm). Recently, we have improved the method by equipping the microscope with a low power He-Ne laser. Highly coherent laser beam focused on the micro-object did not allow to form a real micro-image, but allowed to measure small displacements of the scattering structure via registration of the changes in the intensity of light scattered from the structure moving across the focused spot of laser light. Using the laser as a light source lead to an enhancement of the sensitivity of the apparatus, allowing the registration of displacements with amplitudes down to 1-2 μm.