Diffraction grating based interferometric systems and methods
First Claim
1. An interferometer comprising:
- a low coherence light source;
a first beam splitter in communication with the light source to split light from the light source into a first sample light beam to be directed onto a sample and a reference light beam, wherein a second sample light beam is received by the interferometer from the sample;
a diffraction grating positioned to diffract at least one of the reference light beam and the second sample light beam;
a second beam splitter positioned to receive the second sample light beam and the reference light beam, wherein at least one of the second sample light beam and the reference light beam has been diffracted by the diffraction grating, and the second sample light beam and the diffracted reference light beam are combined in the second beam splitter to form a combined light beam; and
a detector positioned to receive the combined light beam from the second beam splitter.
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Abstract
Diffraction grating based fiber optic interferometric systems for use in optical coherence tomography, wherein sample and reference light beams are formed by a first beam splitter and the sample light beam received from a sample and a reference light beam are combined on a second beam splitter. In one embodiment, the first beam splitter is an approximately 50/50 beam splitter, and the second beam splitter is a non 50/50 beam splitter. More than half of the energy of the sample light beam is directed into the combined beam and less than half of the energy of the reference light beam are directed into the combined beam by the second beam splitter. In another embodiment, the first beam splitter is a non 50/50 beam splitter and the second beam splitter is an approximately 50/50 beam splitter. An optical circulator is provided to enable the sample light beam to bypass the first beam splitter after interaction with a sample. Two combined beams are formed by the second beam splitter for detection by two respective detectors. More than half of the energy of the light source provided to the first beam splitter is directed into the sample light beam and less than half of the energy is directed into the reference light beam. The energy distribution between the sample and reference light beams can be controlled by selection of the characteristics of the beam splitters.
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Citations
73 Claims
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1. An interferometer comprising:
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a low coherence light source;
a first beam splitter in communication with the light source to split light from the light source into a first sample light beam to be directed onto a sample and a reference light beam, wherein a second sample light beam is received by the interferometer from the sample;
a diffraction grating positioned to diffract at least one of the reference light beam and the second sample light beam;
a second beam splitter positioned to receive the second sample light beam and the reference light beam, wherein at least one of the second sample light beam and the reference light beam has been diffracted by the diffraction grating, and the second sample light beam and the diffracted reference light beam are combined in the second beam splitter to form a combined light beam; and
a detector positioned to receive the combined light beam from the second beam splitter. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. An interferometer comprising:
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a first low coherence light source and a second low coherence light source, each emitting light at a different wavelength;
a first beam splitter in communication with the first and second light sources to split the light from the light sources into a first sample light beam to be directed onto a sample and a reference light beam, wherein a second sample light beam is received by the interferometer from the sample;
a diffraction grating positioned to diffract at least one of the reference light beam and the second sample light beam;
a second beam splitter positioned to receive the reference light beam and the second sample light beam, wherein at least one of the reference light beam and the sample light beam has been diffracted by the diffraction grating, the second beam splitter forming two combined light beams;
a first detector positioned to receive one of the combined light beams; and
a second detector positioned to receive the other of the combined light beams. - View Dependent Claims (17, 18, 19, 20, 21)
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22. An interferometer comprising:
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a low coherence light source;
a first, fiber optic beam splitter;
a first optical fiber optically coupling the light source to the first beam splitter, wherein the first beam splitter splits light received from the light source into a sample light beam and a reference light beam;
a second optical fiber to convey the sample light beam onto a sample and to convey a second sample light beam received from the sample to the first beam splitter;
a second beam splitter;
a third optical fiber optically coupling the first beam splitter to the second beam splitter to convey the second sample light beam, at least in part, from the first beam splitter to the second beam splitter;
a diffraction grating;
a fourth optical fiber optically coupling the first beam splitter to the diffraction grating to convey the reference light beam, at least in part, to the diffraction grating;
wherein the second beam splitter is positioned to receive the diffracted reference light beam and the reference light beam and the second sample light beam are combined in the second beam splitter to form a combined light beam; and
a detector positioned to receive the combined light beam. - View Dependent Claims (23, 24, 25, 26, 27, 28, 29, 30, 31, 32)
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33. An interferometer comprising:
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a low coherence light source;
a first fiber optic beam splitter;
a first optical fiber optically coupling the light source to the first beam splitter, wherein the first beam splitter splits light received from the light source into a sample light beam and a reference light beam;
an optical circulator having a first port, a second port and a third port, wherein light input to the first port exits the optical circulator from the second port and light entering the second port exits the optical circulator from the third port;
a second optical fiber optically coupling the first beam splitter to the first port of the optical circulator;
a third optical fiber to convey the sample light beam to a sample and to convey a second sample light beam received from the sample to the first beam splitter;
a second beam splitter;
a fourth optical fiber optically coupling the third port of the optical circulator to the second beam splitter, wherein the third optical fiber conveys the second sample light beam, at least in part, from the third port to the second beam splitter;
a diffraction grating;
a fifth optical fiber optically coupling the first beam splitter to the diffraction grating to convey the reference light beam, at least in part, to the diffraction grating;
the second beam splitter being positioned to receive the diffracted reference light beam from the diffraction grating, wherein the reference light beam and the second sample light beam combine in the beam splitter to form a combined light beam; and
a detector positioned to receive the combined beam - View Dependent Claims (34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52)
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53. An interferometer comprising:
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a low coherence light source;
a first beam splitter in communication with the light source to split light from the light source into a sample light beam to be directed onto a sample and a reference light beam wherein a second light beam is received by the interferometer from the sample;
a second beam splitter for generating two combined light beams from the second sample light beam and the reference light beam, wherein an optical path difference has been introduced into at least one of the second sample light beam and the reference light beam;
first and second detectors, each positioned to receive one of the combined light beams;
first and second polarization filters, each filtering light with respect to a different polarization, the first polarizing filter being between the second beam splitter and the first detector and the second polarizing filter being between the second beam splitter and the second detector.
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- 54. The interferometer of claim 54, wherein each detector is a multi-element detector.
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58. A method of imaging a sample material comprising the steps of:
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splitting a low coherence light beam into a sample light beam and a reference light beam;
directing the sample light beam onto a sample and receiving a second sample light beam from the sample;
diffracting one of the reference light beam and the second sample light beam;
after the diffracting step, combining the second sample light beam with the diffracted light beam by a beam splitter to form a combined light beam; and
detecting the combined light beam with a detector. - View Dependent Claims (59, 60, 61, 62, 63, 68, 69, 70)
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64. A method of analyzing a sample material comprising the steps of:
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splitting a low coherence light beam having an energy into a sample light beam having more than half of the energy of the light beam and a reference light beam having less than half of the energy of the light beam;
directing the sample light beam onto a sample;
diffracting the reference light beam;
combining the light received from the sample with the diffracted reference light beam to form a combined light beam; and
detecting the combined light beam with a detector. - View Dependent Claims (65, 66, 67, 71, 72, 73)
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Specification