As already seen in “Principles of Microscopes and Microscopy (Part I)”, light microscopy can be divided into six sub-categories: bright field microscopy, dark field microscopy, ultraviolet microscopy, fluorescence microscopy, phase contrast microscopy and differential interference contrast (D.I.C).

The so-called ultraviolet microscopy uses ultraviolet light instead of white, common, light, or visible light, as the light source. The ultraviolet light has a wavelength of 180 to 400 nm, much smaller than the visible light, whose wavelength is from 400 to 700 nm. And the advantage is?

Let’s recap how the resolution power is calculated:



According to the above equation, the smaller the wavelength, smaller the resolution power, what means you will be able to observe even smaller objects through the microscope. That said, we can conclude that ultraviolet microscopy enables a useful magnification of about twice the magnification of bright field microscopy.

In addition to promoting a larger magnification, without prejudice of clearness, the ultraviolet microscopy also allows the observation of substances absorbed for microorganisms, which become visible as ultraviolet light reaches upon them and make them fluorescent. This is the main application of ultraviolet microscopy, I mean, histochemical.

The ultraviolet microscope differs from the conventional microscope, for since ultraviolet radiations are not visible, images need to be impressed on a photographic film, by use of an image converter tube, or by the projection on a screen, right after being captured by a phototube. In addition, ultraviolet microscopy needs special lens for the transmission of ultraviolet light and optic resources to reflect the region of interest, 230 to 350 nm.


Don’t miss the next article: fluorescence microscopy.