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High precision small angle generator for realization of the SI unit of plane angle and calibration of high precision autocollimators

A highly precise small angle generator (HPSAG) has been developed in UME to realize the SI unit of plane angle, radian (rad), more precisely and calibrate high precision autocollimators. The device can easily generate small angles in measurement steps of 0.001 arcsec in the measurement range of ±8 arcsec. This enables calibration of high-resolution electronic autocollimators in very small measurement steps close to the autocollimators’ resolution with an expanded uncertainty of 0.01 arcsec (k = 2). Description of the device, method, uncertainty budget and the first results are reported.