Trinocular Microscopes

Written by Patricia Skinner
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Everyone's heard of binoculars, but what about trinoculars? Trinocular microscopes have three objectives, which are the metal tubes that contain the lenses, instead of the usual one, or even two. Why? Well, because nowadays there is a need for a video facility on microscopes, and that's what one of the lenses does.

This type of microscope will often be used for biological or medical applications, as usually their extra functions enable more complicated and closer examination of a specimen. That third eyepiece in trinocular microscopes allows for photo microscopy. Let's take a closer look at the objectives, as these are the "business parts" of a microscope.

The All-Important Lenses

The lens at the bottom of the objective, or that which is closest to the object being viewed, creates a magnified image in an area called the "primary image plane". This eyepiece provides the other half of the magnifying power. Magnifying power times objective power equals magnification.

Objective lenses have many designs and qualities which differ with each manufacturer. Trinocular microscopes can vary widely in the functions of their lenses. The magnification power and the numerical aperture, which are a measure of the limit of resolution of the lens, are both usually inscribed on the barrel of any objective lens.

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