Korea Research Institute of Standards and Science (KRISS) has built a goniometer combining an index table and a small angle generator. The index table divides a circle into 1440(0.25°) and the small angle generator divides 2° with a resolution of 0.002". The integration of a small angle generating facility to the index table allows any 0.002" increment to be generated. The small angle generator is based on the sine bar mechanism that angle is determined from the ratio of two lengths. The rotational angle is measured by a laser angle interferometer that detects the relative motion of two retro-reflectors attached to the rotating arm. The distance between two retro-reflectors is self-calibrated by an index table positioned on the rotating arm. The accuracy of the goniometer system is better than 0.11 second over full circle without calibration of the index table.
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