The Pinhole Autocollimator is a precision instrument for measuring exceedingly small angular displacement of polished reflective surface. The pinhole Autocollimator differs from the Autocollimator in the way it is used. It is more specific in usage. The Autocollimator can be used in a variety of measurements principle of operation for both the instruments is the same. Pinhole Autocollimator can be used for evaluating alignment of machine surfaces, surface plate flatness and squareness of the surface to another, straightness of shaft and a variety of other orientation measurements.​