That used to be prohibitively expensive, but not with what we are offering. This is illustrated in the picture above. It has never been known outside of Russia until now, and we are the only maker offering this method. This uses differences in refractive index to produce a shadow effect. Description of how it works is beyond this description, but it is well described in the books we sell.
Fluorescence microscopy is a specialized technique, but invaluable when it can be used.
For example, when chlorophyll is illuminated at 440 nm, i.e. in the blue part of the spectrum, it emits much dimmer light at 665 nm, that is, red light. Many chemical stains are available to show particular cellular features. Acridine orange, for example, stains chromosomes, so that they will fluoresce as green. A fluorescence microscope illuminates the specimen from above. The so-called excitation light passes through an appropriate filter, through the objective.