Interferometer for determining characteristics of an object surface
AssigneeZygo Corporation
InventorsXavier Colonna De Lega, Peter De Groot
Life of this patent
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Abstract
Disclosed is a system including: (i) an interferometer configured to direct test electromagnetic radiation to a test surface and reference electromagnetic radiation to a reference surface and subsequently combine the electromagnetic radiation to form an interference pattern, the electromagnetic radiation being derived from a common source; (ii) a multi-element detector; and (iii) one or more optics configured to image the interference pattern onto the detector so that different elements of the detector correspond to different illumination angles of the test surface by the test electromagnetic radiation.
Claims25
An apparatus comprising:
- an interferometer configured to direct test light to a test surface over a range of illumination angles and subsequently combine it with reference light to form an interference pattern, the test and reference light being derived from a common source;
- the common source;
- a multi-element detector;
- and
- one or more optics configured to direct at least a portion of the combined light to the detector so that different elements of the detector correspond to different illumination angles of the test surface by the test light;
- wherein the common source is a tunable source, the interferometer comprises a reference surface positioned to reflect the reference light, and the reference surface is further positioned to produce a non-zero optical path length difference with the test light at the interference pattern.
An apparatus comprising:
- an interferometer configured to direct test light to a test surface over a range of illumination angles and subsequently combine it with reference light to form an interference pattern, the test and reference light being derived from a common source;
- a multi-element detector;
- and
- one or more optics configured to direct at least a portion of the combined light to the detector so that different elements of the detector correspond to different illumination angles of the test surface by the test light;
- wherein the interferometer comprises a multi-position mount configured to support multiple objectives and position a selected objective in the path of input light from the common source, the multiple objectives including at least one interference objective.
An interferometry method, comprising:
- providing test and reference light derived from a tunable common source;
- varying the wavelength of the tunable common source
- directing test light to a test surface to provide illumination of the test surface over a range of illumination angles;
- subsequently combining the test light with reference light to form an interference pattern, wherein the optical path lengths of the test and reference light are unequal at the interference pattern;
- directing at least a portion of the combined light to a multi-element detector so that different elements of the detector correspond to different illumination angles of the test surface by the test light;
- and
- detecting a series of interference images in response to varying the wavelength of the tunable common source.
Dependencies are inferred from the claim text.