Interferometer spectrometer with reduced alignment sensitivity
First Claim
1. An interferometer spectrometer, comprising:
- a beam splitter for splitting an input ray into a first ray and a second ray having a first path and a second path, the first ray and the second ray exiting the beam splitter in parallel;
a means for redirecting the first and second rays back toward the beam splitter to define a first path length and a second path length, respectively, the first ray and the second ray striking the redirecting means in parallel; and
a means for generating a difference between the first and second path lengths, wherein the first ray and the second ray optically interact with the beam splitter, the redirecting means, and the means for generating a path length difference.
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Abstract
An interferometer spectrometer that has reduced alignment sensitivity is described herein. Parallelism of an output ray pair formed by a single input ray is not affected by variations in relative alignment of the components. In comparison to other compensated interferometer designs, lateral separation errors in the output ray pair due to optical component misalignment are reduced. The reduced alignment sensitivity may be accomplished by utilizing simple planar components that are common to both light paths. The reduced alignment sensitivity and simplicity in design provides a more compact and more robust interferometer, with reduced manufacturing costs associated therewith. An elliptical field of view light source that utilizes an array of collimator lenses is also described. The light source provides a more compact design than a single circular collimator lens of the same area, and is suitable for single channel or multi-channel use.
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Citations
63 Claims
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1. An interferometer spectrometer, comprising:
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a beam splitter for splitting an input ray into a first ray and a second ray having a first path and a second path, the first ray and the second ray exiting the beam splitter in parallel;
a means for redirecting the first and second rays back toward the beam splitter to define a first path length and a second path length, respectively, the first ray and the second ray striking the redirecting means in parallel; and
a means for generating a difference between the first and second path lengths, wherein the first ray and the second ray optically interact with the beam splitter, the redirecting means, and the means for generating a path length difference. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
an interferometer spectrometer as in claim 1;
a light source generating the input ray, the light source optically connected the interferometer;
a means for introducing one or more test samples into the input ray, the introducing means disposed between the light source and the interferometer; and
a light collector for receiving the output ray pair, the light collector optically connected the interferometer.
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18. An interferometer spectrometer, comprising:
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a beam splitter for splitting an input ray into a first ray and a second ray having a first path and a second path, the beam splitter having flat and parallel leading and trailing surfaces with homogenous refractive material disposed therebetween;
a flat end mirror terminating the first path and the second path to define a first path length and a second path length, respectively, wherein the end mirror reflects the first and second rays back to the beam splitter to combine the rays into an output ray pair, wherein the rays forming the output ray pair are parallel;
a compensator disposed between the beam splitter and the end mirror for equalizing the optical path lengths of the first and second paths, the compensator having flat and parallel leading and trailing surfaces with homogenous refractive material disposed therebetween; and
a means for generating a difference between the first and second path lengths to create an interference pattern in the output ray pair, wherein the path length difference generating means is common to both the first and second paths. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25, 26)
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27. An interferometer spectrometer, comprising:
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a beam splitter for splitting an input ray into a first ray and a second ray having a first path and a second path, the beam splitter comprising a plate having flat and parallel surfaces;
a flat end mirror terminating the first path and the second path to define a first path length and a second path length, respectively, wherein the end mirror reflects the first and second rays back to the beam splitter to combine the rays into an output ray pair, wherein the rays forming the output ray pair are parallel;
a compensator disposed between the beam splitter and the end mirror for equalizing the optical path lengths of the first and second paths, the compensator comprising a plate having flat and parallel surfaces; and
a means for generating a difference between the first and second path lengths to create an interference pattern in the output ray pair, wherein the path length difference generating means is common to both the first and second paths;
wherein translational changes in relative position between the beam splitter, the compensator and the end mirror do not result in a lack of parallelism or a lateral separation between the rays forming the output ray pair.
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28. An interferometer spectrometer, comprising:
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a beam splitter for splitting an input ray into a first ray and a second ray having a first path and a second path, respectively;
an end mirror terminating the first path and the second path to define a first path length and a second path length, respectively, wherein the end mirror reflects the first and second rays back to the beam splitter along the first and second paths, respectively, to combine the rays into an output ray pair;
a compensator disposed between the beam splitter and the end mirror for equalizing the optical path lengths of the first and second paths; and
a means for generating a difference between the first and second path lengths to create an interference pattern in the output ray pair, the path length difference generating means disposed in the first and second paths such that the first and second rays pass therethrough. - View Dependent Claims (29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44)
an intersection mirror for causing the first and second paths to intersect at the intersection point, the intersection mirror disposed between the beam splitter and the end mirror.
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36. An interferometer spectrometer as in claim 28, wherein the path length difference generating means comprises rotation of the beam splitter.
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37. An interferometer spectrometer as in claim 28, wherein the path length difference generating means comprises rotation of the compensator.
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38. An interferometer spectrometer as in claim 32, wherein the path length difference generating means comprises rotation the scanner.
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39. An interferometer spectrometer as in claim 28, wherein the input ray is provided by a light source, and wherein the light source produces an elliptical angular subtense.
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40. An interferometer spectrometer as in claim 39, wherein the light source includes a collimator lens having an array of transmitting fibers disposed adjacent an array of receiving fibers.
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41. An interferometer spectrometer as in claim 39, wherein the light source includes a plurality of collimator lenses each having an array of transmitting fibers disposed adjacent an array of receiving fibers.
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42. An interferometer spectrometer as in claim 41, wherein the lenses are arranged in parallel.
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43. An interferometer spectrometer as in claim 39, wherein a single channel is utilized.
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44. An interferometer spectrometer as in claim 39, wherein multiple channels are utilized.
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45. An interferometer spectrometer, comprising:
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a beam splitter comprising a block of refractive material having parallel first and second surfaces, the second surface having a partially reflective material thereon for splitting an input ray into a first ray and a second ray having a first path and a second path, respectively, the first surface having a reflective material thereon for reflecting the first ray such that the first and second rays exit the beam splitter in parallel;
an end mirror terminating the first path and the second path to define a first path length and a second path length, respectively, wherein the end mirror reflects the first and second rays back to the beam splitter along the first and second paths, respectively, to combine the rays into an output ray pair;
a compensator comprising a plate of refractive material having parallel sides, the compensator disposed between the beam splitter and the end mirror for equalizing the optical path lengths of the first and second paths; and
a means for generating a difference between the first and second path lengths to create an interference pattern in the output ray pair, wherein the path length difference generating means is common to both the first and second paths. - View Dependent Claims (46, 47, 48, 49, 50, 51, 52, 53, 54)
an intersection mirror for causing the first and second paths to intersect at the intersection point, the intersection mirror disposed between the beam splitter and the end mirror.
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52. An interferometer spectrometer as in claim 45, wherein the path length difference generating means comprises rotation of the beam splitter.
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53. An interferometer spectrometer as in claim 45, wherein the path length difference generating means comprises rotation of the compensator.
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54. An interferometer spectrometer as in claim 49, wherein the path length difference generating means comprises rotation the scanner plate.
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55. An interferometer spectrometer, comprising:
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a beam splitter comprising a plate of refractive material having parallel leading and trailing surfaces, the trailing surface having a partially reflective material thereon for splitting an input ray into a first ray and a second ray having a first path and a second path, respectively, the leading surface having a reflective material thereon for reflecting the first ray such that the first and second rays exit the beam splitter in parallel;
an end mirror terminating the first path and the second path to define a first path length and a second path length, respectively, wherein the end mirror reflects the first and second rays back to the beam splitter along the first and second paths, respectively, to combine the rays into an output ray pair;
a compensator plate of refractive material having parallel sides for equalizing the amount of refractive material in the first and second paths, the compensator plate disposed between the beam splitter and the end mirror;
an intersection mirror for causing the first and second paths to intersect at an intersection point, the intersection mirror disposed between the compensator and the end mirror; and
a scanner plate of refractive material having parallel sides for generating a difference between the first and second path lengths to create an interference pattern in the output ray pair, the scanner plate disposed at the intersection point. - View Dependent Claims (56, 57, 58)
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59. An interferometer spectrometer, comprising:
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a light source including an array of collimator lenses defining an elliptical angular subtense;
a beam splitter for splitting the input ray into a first ray and a second ray having a first path and a second path, respectively;
an end mirror terminating the first and second paths to define a first path length and a second path length, respectively;
a compensator disposed between the beam splitter and the end mirror for equalizing the optical path lengths of the first and second paths; and
a means for generating a difference between the first and second path lengths. - View Dependent Claims (60, 61, 62, 63)
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Specification