Method and apparatus for the interferometric examination of scattering objects
AssigneeISIS Optronics GmbH
InventorsAlexander Knuttel, Paul Welker, Christian Kugler, Reiner Rygiel
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Abstract
The invention proposes a method for the optimization of the interferometric examination of scattering objects, wherein intensity-modulated light is divided, one beam is directed into an object and the other beam is directed to a reference mirror, the reflected light is guided to a detector module, where it is converted to an interference signal and this signal is evaluated. The method is characterized by the fact that light of at least two different central wavelengths is irradiated and the converted interference signals of both central wavelengths are phase-shifted in order to compensate for their expected dispersion.
Claims17
Apparatus for the interferometric examination of a scattering object with an optical coupler, a reference mirror and a detector module in the light path, the apparatus comprising:
- at least two light sources (2, 2′) with different central wavelengths (λ1, λ2);
- a digitalization unit (18) connected to the detector module (15), for digitalization of received, converted interference signals of light of the at least two light sources (2, 2′);
- and
- a shifting unit (20) for shifting a phase position of the central wavelength (λ1, λ2) in order to compensate expected dispersion of the phase position.
A method for interferometric examination of a scattering object using an interferometer having a light source, a sample arm, a reference arm and a detector arm, the method comprising the steps of:
- dividing intensity-modulated light of at least two different central wavelengths into a first partial beam, traveling along the sample arm, and a second partial beam, traveling along the reference arm;
- irradiating the scattering object with the first partial beam to produce scattered light;
- directing the second partial beam to a reference mirror to produce a reflected second partial beam;
- combining at least some of the scattered light and at least some light of the reflected second partial beam along the detector arm to a detector module;
- opti-electronically converting the combined scattered light and light of the reflected second partial beam in the detection module into at least two interference signals with different central wavelength;
- and
- shifting the converted interference signals relative to each in order to compensate expected dispersion of phase position.
Apparatus for the interferometric examination of a scattering object, the apparatus comprising:
- at least two light sources (2, 2′) with different central wavelengths (λ1, λ2);
- an optical combiner (4) for combining light from each of the at least two light sources into an optical waveguide (5);
- an optical coupler (6) for dividing the combined light into a sample arm (7) and a reference arm (8), said sample arm (7) being disposed for irradiating the scattering object with a first partial beam of the divided light and receiving scattered light, said referenced arm (8) being disposed for irradiating a mirror (12) and receiving reflected light;
- a light detector (14) for receiving both scattered and reflected light;
- a digitalization unit (18) connected to said light detector (14) for digitalization of received converted interference signals between the scattered and reflected light from the two light sources;
- and
- a shifting unit (20) for shifting a phase position of the centered wavelengths (λ1, λ2) in order to compensate expected dispersion of the phase position.
Dependencies are inferred from the claim text.