These instruments achieve extremely high-precision optical measurements by applying the principles of autocollimation. Using a reflective surface, such things as the differences, variations and deviations of the microscopic edges of the object are read and a wide variety of measurements can be taken concerning deviations in its straightness, perpendicularity, parallelism, flatness and the like.
The Autocollimator 6B-LED makes high-precision measurements simultaneously on two axes with the brightfield technique, while the Autocollimator 6D-LED, with the darkfield technique, can be used for measurements like those for a plane mirror with a small surface area.

Telescope magnification	38 x
Objective	f= 700 mm; effective aperture: 70 mm
Measuring range	30 minutes of arc (both vertical and horizontal axes)
Minimum reading	0.5 seconds of arc
Readout system	Adjustment in viewfield and reading on micrometer
Measuring accuracy	0.5 seconds of arc within a range of 5 minutes of arc 1 second of arc within a range of 30 minutes of arc
Viewfield	6B-LED: bright-field, 6D-LED: dark-field
Light source	LED
Power supply	12V 5A (AC adapter is required) or size AA battery ×2
Dimensions of main body	Outer diameter of lens barrel support: 68 mm Overall length: Approx. 490 mm
Weight (including stand)	Approx. 32 kg