Microscope diagram – parts of a compound upright microscope

Compound microscopes are interesting. They let you see objects and organisms far too small to be seen with the naked eye, simply by shining a light into some transparent lenses. 

But while the concept is simple, the design is a little more complicated.

Here’s a look at all the different parts of a microscope, so that you can get a better idea of how a microscope works. 

Wide-field eyepieces WF10x/18

The eyepieces are what you look down to see your specimens. They generally contain a lens that magnifies the image 10 times (10x) as seen here, but some specialised uses call for 20x lenses.

Some eyepieces can give you a wider field of view than others – these are known as wide-field (WF). Here, the ‘18’ denotes the 18mm field of view the eyepieces provide.

Camera port

Trinocular microscopes have a third eyepiece (the ‘tri’) designed specifically to allow cameras to be attached to the microscope. Because of this, this third eyepiece is often known as the camera port.

Diopter adjustment rings

For most people, the left eye sees a little differently to the right eye. The diopter adjustment rings allow you to adjust the focus of the individual eyepieces to compensate for any visual imbalance between your eyes.

Sliding interpupillary adjustment grips

The distance between your eyes is rarely the same as anyone else’s, so whenever a different person uses your microscope, they’ll need to adjust the distance between the two eyepieces. An adjustable slide lets you move the eyepieces closer or further apart, as needed.

Trinocular head

The head of the microscope houses the eyepieces. This one is trinocular (rather than ‘mono’ or ‘bi’) because it has three eyepieces – two for looking down, and one for a camera, sometimes referred to as a siedentopf binocular microscope head. 

Revolving nosepiece

The revolving nosepiece is a rotatable disc that houses all the objectives lenses of a microscope. It rotates to allow you to switch easily between the different objectives.

Head locking screw

This is simply a screw that attaches the microscope head to the body.

Microscope stand arm

This connects the base of the microscope to the head. It’s often used as a handle when carrying the microscope. The course and fine focusing knobs are located on the stand arm.

Achromatic objective lenses

The heart of a microscope. The objective lenses determine image quality, resolution and the level of magnification. The lenses sit just above the specimen and focus the light into the image that you see through the eyepieces.

Achromatic lenses are the standard microscope objectives. They compensate for chromatic and spherical aberration.

Locking screws

These screws attach the mechanical stage to the microscope.

Specimen holder

As the name implies, the specimen holder holds your glass slides steady and in position.

Stage lateral movement rail

This rail enables the mechanical stage to move your slide to the left or right.

Double layer mechanical stage

Mechanical stages allow you to make fine adjustments to your slide’s position using precise mechanical controls.