Optical system, method of manufacturing an optical system and method of manufacturing an optical element
View Patent ↗A method of positioning optical elements relative to each other uses an interferometer apparatus comprising a plurality of holograms generating beams of adjustment measuring light which are incident on optical surfaces of the optical elements. Interference patterns generated by superimposing adjustment measuring light of the beams reflected from the surfaces are indicative of positioning errors of the optical elements. The beams of adjustment measuring light may comprise focused beams forming a point focus on the optical surface and beams of light which is orthogonally incident on extended portions on the optical surface.
1. A null lens arrangement for an interferometer for testing an optical element, the null lens arrangement comprising:
a first grating configured to diffract measuring light such that measuring light diffracted by the first grating is substantially orthogonally incident on a first optical surface of the optical element in an extended region thereof such that a shape of the first optical surface within the extended region can be determined; and
a second grating configured to diffract measuring light such that measuring light diffracted by the second grating is directed on a second surface such that a distance of the second surface from second grating can be determined.
2. The null lens arrangement according to claim 1 , wherein the second surface is a surface of the optical element.
3. The null lens arrangement according to claim 1 , wherein the second surface coincides with the first surface of the optical element.
4. An interferometer system for testing an optical element, the interferometer system having a null lens arrangement, wherein the null lens arrangement comprises:
a first grating configured to diffract measuring light such that measuring light diffracted by the first grating is substantially orthogonally incident on a first optical surface of the optical element in an extended region thereof such that a shape of the first optical surface within the extended region can be determined; and
a second grating configured to diffract measuring light such that measuring light diffracted by the second grating is directed on a second surface such that a distance of the second surface from second grating can be determined.
5. A method of manufacturing an optical element, the method comprising:
mounting the optical element relative to a null lens arrangement of an interferometer;
diffracting measuring light at a first grating of the null lens arrangement to form a first beam of measuring light which is substantially orthogonally incident on a first optical surface of the optical element;
diffracting measuring light at a second grating of the null lens arrangement to form a second beam of measuring light directed on a second surface;
superimposing light of the first beam of measuring light reflected from the first surface with reference light to generate at least one first interference pattern;
superimposing light of the second beam of measuring light reflected from the second surface with reference light to generate at least one second interference pattern; and
processing the first optical surface based on the at least one first interference pattern and the at least one second interference pattern.
6. A method of operating an optical system, the method comprising:
mounting the optical element relative to a null lens arrangement of an interferometer;
diffracting measuring light at a first grating of the null lens arrangement to form a first beam of measuring light which is substantially orthogonally incident on a first optical surface of the optical element;
diffracting measuring light at a second grating of the null lens arrangement to form a second beam of measuring light directed on a second surface;
superimposing light of the first beam of measuring light reflected from the first surface with reference light to generate at least one first interference pattern;
superimposing light of the second beam of measuring light reflected from the second surface with reference light to generate at least one second interference pattern; and
adjusting a position of the first optical surface relative to the second optical surface based on the at least one first interference pattern and the at least one second interference pattern.