Apparatus for and method of measurement of aspheric surfaces using hologram and concave surface

A method of measuring an aspheric surface, comprising:

• splitting light emitted from a light source into incident light and reference light using an optical path changer;
• passing the incident light to a first optical element with a hologram which diffracts the incident light;
• transmitting the diffracted incident light through a second optical element having a concave surface;
• reflecting the incident light after having passed through the concave surface from a test piece with the aspheric surface to form test light;
• and
• measuring an error in the aspheric surface using interference fringes of the test light and the reference light.

A method of measuring an aspheric surface, comprising:

• splitting light emitted from a light source into incident light and reference light using an optical path changer;
• transmitting the incident light through an optical element having a hologram and a concave surface;
• reflecting the incident light after having passed through the optical element from a test piece with the aspheric surface to become test light;
• and
• measuring an error in the aspheric surface from interference fringes of the test light and the reference light.

An apparatus for measuring an aspheric surface on a test piece, comprising:

• an interferometer which generates a first light to proceed along an optical path to the test piece to be reflected from the aspheric surface to become test light, and which evaluates the test light and the first light to measure an error on the aspheric surface;
• a holographic surface disposed in the optical path of the first light to diffract the incident first light towards the test piece;
• and
• an optical surface disposed between the test piece and the holographic surface and having a shape to reduce an incident angle of the test light incident to the holographic surface.

A method of correcting an aspheric surface, comprising:

• splitting light emitted from a light source into a first light and a reference light;
• transmitting the first light through a holographic surface and a concave surface;
• receiving the first light at the aspheric surface after passing through the holographic and surfaces;
• reflecting the received first light from a test piece with the aspheric surface to become test light;
• measuring an error in the aspheric surface from interference fringes of the test light and the reference light;
• and
• if an error is detected, additionally processing the aspheric surface to correct the measured error.