Measuring optical element for aberration from gravity and holding

A system for measuring an optical element, comprising:

• a rotation/holding module, configured to irradiate a laser ray to an overall portion of the optical element, wherein the optical element is supported as one of a horizontal state and a vertical state;
• a picture capturing module, configured to rotate continuously the optical element with 360 degrees to reflect the laser ray to obtain a reflected light wavefront picture from the reflected laser ray for each of a plurality of specified rotation angles of the optical element;
• a characteristics analysis module, configured to analyze the reflected light wavefront picture for each of a plurality of specified rotation angles of the optical element to obtain a plurality of aberration characteristics information, respectively, each being one of a sine and a cosine wave functions of a wavefront error for each of the plurality of specified rotation angles of the optical element;
• an error analysis module, configured to compare each of the plurality of aberration characteristics information with an ideal sine function and an ideal cosine function to obtain an amplitude difference and a constant amplitude deviation for each of the plurality of specified rotation angles of the optic element, wherein the amplitude difference and the constant amplitude deviation indicates that a measuring system error, an optic element gravity error, and a holding error are existed;
• an error classified-characteristics obtaining module, configured to extract the measuring system error, the optic element gravity error, and the holding error from each of the plurality of aberration characteristics information to obtain a plurality of classified aberration characteristics information;
• and
• an error amount calculation module, configured to analyze each of the plurality of classified aberration characteristics information for each of the plurality of specified rotation angles of the optical element to obtain an error amount corresponding to the manufacture residual-shape error.