Patent ID: 8154735

Claim:
An apparatus for measuring a quasi-static error for measuring a positional error and an angular error generated in each of X, Y, and Z axis directions of a rotating driving shaft through a position detection sensor for sensing an input position of a laser beam, the apparatus comprising: a first position sensor for sensing the input position of the laser beam, the first position sensor being disposed on a center of an upper surface of the driving shaft; a first splitter for spectrally outputting an inputted laser beam as a straight directional laser beam component and horizontal directional laser beam component so that the straight directional laser beam component is inputted to the first position sensor, the first splitter being spaced apart from the first position sensor at a predetermined distance on an extension line of an upper part of the driving shaft and fixed to the driving shaft to rotate together with the driving shaft; a second position sensor spaced apart from the first splitter at a predetermined distance in a horizontal spectral direction of the first splitter so as to receive the horizontal directional laser beam component spectrally outputted from the first splitter and fixed to the driving shaft to rotate together with the driving shaft; a second splitter for spectralizing the inputted laser beam into a straight directional laser beam component and down-vertical directional laser beam component, the second splitter being spaced apart from an upper part of the first splitter on an extension line of the upper part of the driving shaft; a reflector for receiving the straight directional laser beam component split from the second splitter and reflecting the received laser beam component to the first position sensor; a laser driving device disposed on a same horizontal extension line of the second splitter and reflector and opposed to the reflector based on the second splitter, to irradiate the laser beam to the second splitter; and a blocking plate for selectively blocking the straight directional or vertical directional laser beam component split from the second splitter.