Parts of a Compound Microscope

A set of vocabulary flashcards defining each major part of a compound microscope and its function.

Eyepiece (Ocular lens)

The lens at the top of the microscope that you look through, typically providing 10× magnification.

Diopter adjustment

A focusing ring on one eyepiece that compensates for differences between the viewer’s eyes.

Nosepiece

The rotating turret that holds the objective lenses and allows quick switching between magnifications.

Objective lens

Primary lenses located near the specimen, commonly 4×, 10×, 40×, and 100×, that provide most of the magnification.

Stage clips / Slide holder

Metal clips that secure the microscope slide firmly on the stage.

Aperture

The hole in the stage through which light passes to illuminate the specimen.

Condenser

A lens system beneath the stage that focuses and concentrates light onto the specimen.

Iris diaphragm

An adjustable opening below the condenser that regulates the amount and angle of light reaching the specimen to control contrast.

Illuminator

The built-in light source, usually in the base, that provides illumination for viewing the specimen.

Interpupillary adjustment

A mechanism that changes the distance between eyepiece tubes to match the user’s eye spacing.

Eyepiece tube

The tube that holds the ocular lenses at the correct distance from the objectives.

Head

The upper assembly that houses the eyepiece tubes and connects them to the objective nosepiece.

Arm

The curved or straight support that connects the head to the base; used to carry the microscope.

Specimen stage

The flat platform on which the slide rests; can move in the X- and Y-axes for positioning.

Fine focus knob

The smaller knob that makes minute adjustments to achieve sharp focus after coarse focusing.

Coarse focus knob

The larger knob that rapidly moves the stage or head for initial focusing of the specimen.

Stage controls

X- and Y-axis knobs that move the stage left/right and forward/backward for precise slide positioning.

Base

The bottom support of the microscope that houses the illuminator and provides stability.

Brightness adjustment

A dial or knob that controls the intensity of the illuminator’s light output.

Light switch

The on/off switch that powers the microscope’s illuminator.