Microscope glossary of terms and definitions

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Microscope Glossary

Mechanical stage. A type of stage that allows one to move the specimen slide in the X or Y direction a precise distance by turning a knob. Very useful at higher magnifications.

Monocular microscope. A compound microscope with one eyepiece.

Nosepiece. Also called the turret, the part of the microscope that holds the objective lenses.

Numerical Aperture (NA). The ability of a lens to resolve fine detail in an object being observed. It is related to the aperture of the lens and the index of refraction of the medium found between the lens and the specimen.

Objective lens. The lens in a microscope closest to the specimen. In a compound microscope there are usually 3 to 5 objective lenses mounted in the nosepiece, allowing a selection of different magnification powers.

Parcentered. A lens design that allows specimens to remain centered in the field of view at multiple magnification levels.

Parfocal. A lens design such that allows specimens to remain focused at different magnification powers.

Phase contrast. An optical technique used to better view the structure of transparent objects whose differences in thickness result in differences in the phase of transmitted light. Found on advanced microscopes.

Post stand. A type of stand used with low-power microscopes. The microscope body can rotate about the post and also up and down.

Rack and Pinion. A microscope focusing mechanism where the rack is a track with teeth and the pinion is a gear that travels up and down the track. By turning a focus knob, the microscope moves closer or further away from the specimen.

Rack Stop. The rack stop keeps you from cranking the objective lenses too far down and causing damage.

Resolution. The ability of a lens to show fine details of the object being observed.

Reticle. A tiny grid pattern etched on an eyepiece lens. It is used to make measurements of the size of objects seen through a microscope. Also called an eyepiece micrometer.

Retractable objective (XR). A spring located inside the objective lens so that minimal damage is done to the slide and the top element of the lens should the microscope be cranked down too far.

Ring light. An external light source that usually attaches to the microscope body and gives off a 360° ring of light. Also called annular light.