Stereo microscope parts diagram with labels and functions

Parts of a stereo microscope

Stereo microscopes (both eyes) have come a long way since they were invented by a French monk over 300 years ago.

They’ve gone from handcrafted novelties to sophisticated and varied tools indispensable to science and industry. From surgery and biology to engineering and repair, they’ve become an essential part of our lives – whether or not we know it.

But at bottom, all this amazing functionality is based on a common platform. To give you a better idea of how stereo microscopes work, here’s a breakdown of their main components.


Optico ASZ-400T Trinocular Stereo Zoom Microscope & LED Stand


The microscope eyepiece lets you see your samples while also providing a set level of magnification. The eyepieces can usually be swapped out for different magnifications as needed, although the default is 10x.

They can also be moved closer together or farther apart to suit the distance between your eyes.

Camera port

The camera port (also known as a trinocular port) lets you attach a camera to your microscope so you can take photos or video while you work.

You can attach more traditional cameras such as DSLRs, as well as a variety of digital camera options. You can even stream the microscope image directly to a computer, TV or tablet.


The ‘diopter’ is a simple adjustable ring on the eyepiece.

It allows you to adjust the focus of the individual eyepieces to compensate for the difference in vision between your eyes.

Most people have stronger vision in one eye, and you end up with one eyepiece a bit out of focus. Adjusting the diopter lets you have both eyepieces in focus at the same time.

Zooming Knob

This knob lets you adjust the magnification setting of your microscope. It helps you to zoom in on a particular area for a close view.

For continuous zoom microscopes, you can adjust the magnification anywhere within a set range. On a dual power microscope, you can switch between two pre-set magnification settings.

Optical head

The optical head is the structure that fits on top of the microscope frame and houses the eyepieces and lenses. Stereo heads can be either binocular or trinocular, depending on whether or not they have a camera port.

Focusing knob

This knob adjusts the focus of the microscope. It moves the optical head up or down to bring your sample into sharp focus.

Top lighting

This lighting array illuminates your samples from above. It’s useful for opaque samples that are best seen with reflected light, such as circuits or insects.

Bottom lighting

This lighting array sits below the stage. It’s handy for thin or transparent samples where transmitted light is more useful.

Lighting controls

The controls to the lighting arrays. Depending on the microscope, the top and bottom lighting can be switched on or off, and the intensity can be adjusted.

Stage plate

The stage plate is the platform where you place your specimens. Plates can come in light or dark colours to provide better contrast for a particular sample.

And there you have it, the surprisingly simple features of the microscope that helped design your smart phone and computer – and, in the hands of a surgeon, may one day save your life!

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