Interferometer for measuring optical phase differences
AssigneeCarl-Zeiss-Stiftung
InventorMichael Kuchel
Life of this patent
Estimating the term…
Abstract
For generating several interferograms which differ from each other in the relative phase position between the interfering partial beams, a light source is utilized having a coherence length less than the optical path difference between the two component beams in the measuring path of the interferometer. Furthermore, at least one optical delay device is provided which splits the beam into two component beams and which generates an optical path difference between these component beams which is approximately the same as the optical path difference of the partial beams in the measuring path of the interferometer. Thereafter, the delay device again unites the component beams congruently.
Claims16
An interferometer for measuring optical phase differences which occur between two partial beams reflected from a reference surface and from the surface of the part to be measured, respectively, the interferometer comprising:
- light source means for providing a coherent beam directed along a beam path;
- optical delay means for splitting said beam into first and second component beams and for generating a first optical path difference between said first and second component beams and for then congruently recombining said component beams;
- optical directing means for directing said first and second component beams toward the reference surface and the measurement surface of the part to be measured whereat said partial beams occur and a second optical path difference is generated between said partial beams;
- said optical delay means including adjusting means for adjusting said first optical path difference to be approximately equal to said second optical path difference;
- said light source means having a coherence length that is less than said second optical path difference;
- spatially-resolving receiver means;
- and,
- optical means for transmitting said partial beams reflected from said reference surface and said measurement surface, respectively, so as to image said reference surface and said measurement surface on said receiver means.
Dependencies are inferred from the claim text.