Measurements of optical inhomogeneity and other properties in substances using propagation modes of light
First Claim
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1. A method for optically measuring a sample comprising:
- directing one beam of guided light in a first propagation mode to a sample;
directing a first portion of the guided light in the first propagation mode at a location near the sample away from the sample before the first portion reaches the sample while allowing a second portion in the first propagation mode to reach the sample;
controlling a reflection of the second portion from the sample to be in second propagation mode different from the first propagation mode to produce a reflected second portion;
directing both the first portion in the first propagation mode and the reflected second portion in the second propagation mode through a common waveguide into a detection module to extract information from the reflected second portion on the sample;
adjusting a relative phase delay between the reflected first portion and the reflected second portion to a first value to measure a first signal associated with a first layer within the sample;
adjusting the relative phase delay to a second, different value to measure a second signal associated with a second layer within the sample; and
obtaining a ratio between the first and the second signals to extract information about a layer of the sample located between the first and the second layers.
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Abstract
This application describes designs, implementations, and techniques for controlling propagation mode or modes of light in a common optical path, which may include one or more waveguides, to sense a sample.
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Citations
83 Claims
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1. A method for optically measuring a sample comprising:
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directing one beam of guided light in a first propagation mode to a sample;
directing a first portion of the guided light in the first propagation mode at a location near the sample away from the sample before the first portion reaches the sample while allowing a second portion in the first propagation mode to reach the sample;
controlling a reflection of the second portion from the sample to be in second propagation mode different from the first propagation mode to produce a reflected second portion;
directing both the first portion in the first propagation mode and the reflected second portion in the second propagation mode through a common waveguide into a detection module to extract information from the reflected second portion on the sample;
adjusting a relative phase delay between the reflected first portion and the reflected second portion to a first value to measure a first signal associated with a first layer within the sample;
adjusting the relative phase delay to a second, different value to measure a second signal associated with a second layer within the sample; and
obtaining a ratio between the first and the second signals to extract information about a layer of the sample located between the first and the second layers. - View Dependent Claims (2, 3)
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4. A method for optically measuring a sample, comprising:
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directing one beam of guided light in a first propagation mode to a sample;
directing a first portion of the guided light in the first propagation mode at a location near the sample away from the sample before the first portion reaches the sample while allowing a second portion in the first propagation mode to reach the sample;
controlling a reflection of the second portion from the sample to be in a second propagation mode different from the first propagation mode to produce a reflected second portion, directing both the first portion in the first propagation mode and the reflected second portion in the second propagation mode through a common waveguide into a detection module to extract information from the reflected second portion on the sample;
adjusting a relative phase delay between the reflected first portion and the reflected second portion to a value to select a layer from which a reflection component in the reflected second portion substantially matches the reflected first portion in phase, modulating the relative phase around the value at a modulation frequency to obtain a measurement; and
processing the measurement to obtain information on the layer. - View Dependent Claims (5)
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6. A method for optically measuring a sample, comprising;
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directing one beam of guided light in a first propagation mode to a sample;
directing a first portion of the guided light in the first propagation mode at a location near the sample away from the sample before the first portion reaches the sample while allowing a second portion in the first propagation mode to reach the sample. controlling a reflection of the second portion from the sample to be in a second propagation mode different from the first propagation mode to produce a reflected second portion, directing both the first portion in the first propagation mode and the reflected second portion in the second propagation mode through a common waveguide into a detection module to extract information from the reflected second portion on the sample; and
adjusting a relative lateral position between the second portion and the sample to direct the second portion to reach different locations on the sample to obtain information at the different locations. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. A device for optically measuring a sample, comprising:
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a waveguide to receive and guide an input beam in a first propagation mode;
a probe head coupled to the waveguide to receive the input beam and to reflect a first portion of the input beam back to the waveguide in the first propagation mode and direct a second portion of the input beam to a sample, the probe head collecting reflection of the second portion from the sample and exporting to the waveguide the reflection as a reflected second portion in a second propagation mode different from the first propagation mode; and
a detection module to receive the reflected first portion and the reflected second portion in the waveguide and to extract information of the sample carried by the reflected second portion. - View Dependent Claims (25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54)
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55. An apparatus for optically measuring a sample, comprising:
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a) a light source;
b) a waveguide supporting at least first and second independent propagation modes and guiding the light radiation from the light source in the first propagation mode to the vicinity of a sample under examination;
c) a probe head that terminates the waveguide in the vicinity of the sample and reverses the propagation direction of a portion of the first propagation mode in the waveguide while transmitting the remainder of the light radiation to the sample, the probe head operable to convert reflected light from the sample into the second propagation mode;
d) a differential delay modulator that transmits the light in both the first and the second propagation modes from the probe head and the waveguide and varies the relative optical path length between the first and the second propagation modes;
e) a mode combiner to receive light from the differential delay modulator and operable to superpose the first and the second propagation modes by converting a portion of each mode to a pair of new modes;
f) at least one photodetector to receive light in at least one of the two new modes; and
g) an electronic controller in communication with the photodetector and operable to extract information of the sample from the output of the photodetector. - View Dependent Claims (56, 57, 58)
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59. An apparatus for optically measuring a sample, comprising:
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a first waveguide capable of maintaining at least one propagation mode;
a light source that emits radiation to excite the propagation mode in the first waveguide;
a light director that terminates the first waveguide with its first port and passes the light mode entering the first port, at least in part, through a second port and passes the light modes entering the second port, at least in part, through a third port;
a second waveguide that supports at least two independent propagation modes and having a first end coupled to the second port and a second end;
a probe head coupled to the second end of the second waveguide and operable to reverse the propagation direction of the light in part back to the second waveguide and to transmit the remainder to the sample, the probe head further operable to transform the collected light from the sample reflection to an orthogonal mode supported by the second waveguide and direct light in the orthogonal mode into the second waveguide;
a third waveguide supporting at least two independent propagation modes and being connected to the third port of the light director to receive light therefrom;
a differential delay modulator that connects to the third waveguide to receive light from the second waveguide and imposes a variable phase delay and a variable path length on one mode in reference to the other;
a fourth waveguide supporting at least two independent modes and coupled to the differential delay modulator to receive light therefrom; and
a detection subsystem positioned to receive light from the fourth waveguide and to superpose the two propagation modes from the fourth waveguide to form two new modes, mutually orthogonal, the detection subsystem comprising two photo-detectors respectively receiving light in the new modes. - View Dependent Claims (60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76)
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77. A device, comprising:
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an optical waveguide to guide an optical radiation in a first optical mode;
an optical probe head coupled to the optical waveguide to receive the optical radiation, the optical probe head operable to (1) redirect a portion of the optical radiation back to the optical waveguide while transmitting the remaining radiation to a sample, (2) receive and direct the reflected or backscattered radiation from the sample into the waveguide, and (3) control the reflected or the backscattered light from the sample to be in a second optical mode different from the first optical mode; and
an optical detection module to receive the radiation redirected by the probe head through the waveguide and to convert optical radiation in the first and second optical modes, at least in part, into a common optical mode. - View Dependent Claims (78, 79, 80)
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81. A device for optically measuring a sample, comprising
an input waveguide, which supports first and second different propagation modes, to receive and guide an input beam in the first propagation mode; -
an output waveguide, which supports first and second different propagation modes;
a probe head coupled to the input waveguide to receive the input beam and to the output waveguide to export light, the probe head operable to direct a first portion of the input beam in the first propagation mode into the output waveguide and direct a second portion of the input beam to a sample, the probe head collecting reflection of the second portion from the sample and exporting to the output waveguide the reflection as a reflected second portion in the second propagation mode; and
a detection module to receive the reflected first portion and the reflected second portion in the output waveguide and to extract information of the sample carried by the reflected second portion. - View Dependent Claims (82, 83)
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Specification