Calibration slide for stereomicroscopes.
The slide has a 10x10 mm grid etched into it. At the center of the slide are crosshairs with two micrometer scales, each with 200 divisions. The scale division is 0.05 mm, and the length of each scale is 10 mm.
The calibration slide (stage micrometer) is used to determine magnification, the microscope's linear field of view, and the division value of eyepiece scales and reticles.
When used with a digital camera, the slide allows the image analysis software to be calibrated for each objective.

Image analysis software calibration

Calibration is performed for each objective used for observations. The calibration slide is used to determine the calibration factor for the image analysis software.

Calibration procedure:

1. Secure the calibration slide on the microscope stage.
2. Select the desired objective and set the camera to its maximum resolution.
3. Obtain a high-contrast image of the scale on the monitor screen and capture the image.
4. Select “Calibration” mode in the image analysis software.
5. Click with the mouse to define the maximum visible distance between the first and last scale divisions.
6. Enter the resulting scale size in real-world units in the image analysis software.
7. Enter the calibration name, specifying the current objective magnification.
8. Check the result: in “Measurement” mode, measure several calibration slide scale divisions in real-world units.
9. The image analysis software will save the calibration factor under the selected name. It will then automatically convert the results into the selected units of measurement.

Eyepiece scale calibration

The eyepiece scale is calibrated for each objective used for observations. Place the slide on the stage, then focus the microscope on the scale. Rotate the eyepiece in the optical tube until the slide scale and eyepiece scale are aligned parallel to each other.

The calculation for each objective is performed using the formula:
Е=ТL/A, where
E – eyepiece division value
Т – stage division value specified on the stage micrometer (0.05 mm)
L – number of stage micrometer divisions
А – number of eyepiece scale divisions.

The corresponding eyepiece scale division values for each objective will thus be recorded.

When measuring an object, first count the number of eyepiece scale divisions covered by the object. Then multiply the result by the scale value previously calculated for the objective in use. The resulting value is the object's true linear dimension.