What is the difference between an ocular micrometer and a stage micrometer?

An ocular micrometer is a scale installed in the eyepiece and appears in the microscope field of view. A stage micrometer is a reference scale placed on the stage and is used to calibrate the ocular micrometer for each magnification or zoom setting.

Why does an ocular micrometer need calibration?

The actual value of one ocular micrometer division changes with objective magnification, zoom setting, eyepiece and optical configuration. Calibration with a stage micrometer is required before reliable specimen measurement.

How should I choose an ocular micrometer size?

Ocular micrometer size should be selected according to the eyepiece reticle diameter and the microscope eyepiece design. The pattern should also match the intended measurement or counting application.

Microscope & Accessory

Microscope Micrometer

Ocular micrometers, stage micrometers and microscope calibration.

Microscope micrometers are used to measure specimen dimensions through the microscope optical system. Accurate measurement requires proper selection of the reticle type, compatible eyepiece size and correct calibration procedure.

Ocular Micrometer Stage Micrometer Calibration Compatible Size Traceability

Ocular and Stage Micrometer

Ocular Micrometer

Eyepiece scale
An ocular micrometer is a glass scale or reticle installed inside the eyepiece. It allows specimen size to be compared against the scale visible in the microscope field of view.
Ocular Micrometer

Stage Micrometer

Reference scale
A stage micrometer is placed on the microscope stage and used as a reference standard. It helps determine the real measurement value of the ocular micrometer scale under each magnification condition.
Stage Micrometer

Microscope Measurement Overview

Ocular micrometers are installed in the eyepiece and show a scale in the field of view.
Stage micrometers are reference scales used to calibrate the ocular micrometer.
Calibration is required because the actual value of one ocular micrometer division changes with magnification and optical configuration.

Reticle diameter must match the eyepiece design and compatible size requirements.
Stage micrometers are used for calibration checks, microscope setup and measurement reliability.
Traceability may be required for quality control, inspection records or regulated measurement workflows.