Periscopic Eye Piece Microscopes

Periscopic Eye-Piece Microscope

This consists of a triple eye-lens and single field-lens. Its predominant feature is a very large and flat field, with almost all objectives. In this respect it has a considerable advantage over the Huyghenian and Solid. It is positive and therefore well adaped for micrometer work, as it is focused like a magnifier, and its magnifying power remains constant, while with the Huyghenian it is variable, from the fact that the eye-lens alone is focused, thus varying its distance from the field-lens, and consequently the magnifying power. Nomenclature. The rating of eye-pieces was formerly, and is to a considerable extent today, by letters. This method, however, is arbitrary, as the letters of different makers have a totally different significance, so that nothing like a standard exists. This fact induced the American Society of Microscopists to endeavor to establish a universal method, and after the matter had been given careful attention for several successive years, it finally adoped the method which rates them according to their magnifying powers, the same as that which has been used in objectives. .This gives an approximate idea of the magnifying powers ; thus, an eye-piece marked 1 inch or by a letter signifying the same, shows that it magnifies about 10 diameters ; one of 1 inch, 20 diameters, and so on.

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