The autocollimator projects an image of a reference cross wire to the object under inspection and receive the reflected image from the object. Shift in the reflected image compared to the fixed reference crosswire represents angle. A linear stage driven by a micrometer carries the fixed cross wire near to the eyepiece of the instrument. Operator can determine shift and hence the angle by moving the fixed cross wire and aligning it with the reflected image. Graduations on the micrometer give angular measurements directly in arc seconds.

In most cases, the object under inspection may not be having reflective surfaces. In order to carry out inspection, operator needs to fix a plane mirror to the object for reflecting back the light to the instrument. Holmarc supplies a front coated mirror along with kinematic mount as a standard accessory along with auto-collimator.

Holmarc’s auto-collimator has stainless steel body and high precision optics. Illumination is by an LED. A kinematic stage with two axes tilt movements holds the instrument on a height adjustable stand. A heavy cast iron base provides required stability for measurements.