The ultramicroscope is a light optical microscope that enables the visualization of sub-micron dispersed particles. The working principle is based on darkfield imaging using an extremely high numerical aperture illumination. This is achieved by the cyto-viva condenser arrangement. Simply speaking this generates a quasi-perpendicular illumination of the sample particles so that the direct illumination doesn´t enter the objective lens. Only photons scattered (by the particles) in direction of the objective lens are detected. This effect is similar to the flashing of dust particles in the air when illuminated by an intense sun light beam against a dark background.
More than just imaging these particles the ultramicroscope can measure their size distribution by tracking the individual particles in the field of view. Off-line calculation of the diffusion coefficient applying Stokes-Einstein equation finally yields a size of every individual particle passing the field of view of the microscope. This size determination method is complementary to dynamic light scattering techniques.
|Objectives:||Zeiss Epiplan Objectives 10x, 40x, 50x and 100x immersion|
|Camera:||Leica BW CCD camera|
|Condensor:||Cyto-Viva exteme darkfield illumination condenser|
|Sample requirements:||Dispersion of nanoparticles in any solvent|