Measurement of deviation of the microscope stage from squareness to the optical axis

The measurement of deviation of microscope stage from squareness to the optical axis is an important parameter in optical testing of microscopes. This test ensures that when the deviation is in the permitted limits, the optical axis of the microscope is normal to the stage and hence the movement of the microscope tube is in normal direction to the stage. In the present article a simple method to measure the deviation of the microscope stage from squareness to its optical axis has been described using a parallel plate and autocollimators. Test results on a few microscopes have been presented.