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US5956355A Expired / Lapsed US ⏱️ 0.0 years remaining

Method and apparatus for performing optical measurements using a rapidly frequency-tuned laser

Assignee: Massachusetts Institute of Technology
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Filing: 1997-06-17
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Granted: 1999-09-21
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Expires: 2017-06-17
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Abstract

Abstract An optical system, in one embodiment including an external-cavity frequency-tuned laser having a tunable longitudinal cavity mode and a center tunable wavelength. The external-cavity frequency-tuned laser includes an optical cavity, an optical gain medium positioned within the optical cavity, and a rapid tuning wavelength selecting device positioned to receive light from the optical gain medium and adapted to return selected wavelengths of light to the optical gain medium. The external-cavity frequency-tuned laser is substantially continuously tunable and the tunable wavelength selecting device tunes the center wavelength of the external-cavity frequency-tuned laser at the same rate as the longitudinal cavity mode of the external-cavity frequency-tuned laser is tuned. In another embodiment the optical system includes an interferometer in optical communication with the external-cavity frequency-tuned laser. The interferometer is adapted to project a portion of light from the external-cavity frequency-tuned laser onto a sample, to receive light altered by the sample, and to combine light reflected from the sample and the light from the external-cavity frequency-tuned laser. A detector positioned to receive the combined light from the interferometer and to generate a signal in response thereto. A processing unit in communication with the detector performs digital signal processing to extract spatial information related to the sample in response to the signal from the detector.

Inventors

  • 👤 Eric A. Swanson
  • 👤 Stephen R. Chinn

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-10-26 10:25
CPC Classifications
A; A61; A61B; A61B5/00; A61B5/0059; A61B5/0062; A61B5/0066; A61B1/00; A61B1/00163; A61B1/00174; A61B1/00183; A61B3/00; A61B3/10; A61B3/1005; A61B3/102; A61B5/0064; G; G01; G01B; G01B11/00; G01B11/24; G01B11/2441; G01B9/00; G01B9/02; G01B9/02001; G01B9/02002; G01B9/02004; G01B9/02041; G01B9/02045; G01B9/02055; G01B9/02062; G01B9/02067; G01B9/02069; G01B9/0207; G01B9/02072; G01B9/0209; G01B9/02091; G01J; G01J1/00; G01N; G01N21/00; G01N21/17; G01N21/47; G01N21/4795; G02; G02B; G02B27/00; G02B27/42; G02B27/4233; G02B27/4244; G02B5/00; G02B5/18; G02B5/1828; H; H01; H01S; H01S3/00; H01S3/05; H01S3/08; H01S3/081; H01S3/0811; H01S3/0812; H01S5/00; H01S5/10; H01S5/14; H01S5/141; A61B2562/00; A61B2562/02; A61B2562/0233; A61B2562/0242; A61B5/44; A61B5/441; A61B5/72; A61B5/7225; B; B82; B82Y; B82Y35/00; G11; G11B; G11B7/00; G11B2007/0003; G11B2007/0009; G11B2007/0013; H01S3/08004; H01S3/08009; H01S3/083; H01S5/06; H01S5/062; H01S5/0625; H01S5/06255; H01S5/12; H01S5/1206; H01S5/1215; H01S5/143; H01S5/146

Claims Analysis

Total Claims: 14
Claim 1
Independent Claim 211 words
An optical system comprising: an external-cavity frequency-tuned laser having a tunable longitudinal cavity mode and a center timable wavelength, said external-cavity frequency-tuned laser comprising: an optical cavity; an optical gain medium positioned within said optical cavity; and a rapid tuning wavelength selecting device positioned to receive light from said optical gain medium and adapted to return selected wavelengths of light to said optical gain medium; an interferometer in optical communication with said external-cavity frequency-tuned laser, said interferometer adapted to project a portion of light from said external-cavity frequency-tuned laser onto a sample and to receive light altered by said sample, said interferometer adapted to combine light reflected from said sample and said light from said external-cavity frequency-tuned laser; a detector positioned to receive said combined light from said interferometer and to generate a signal in response thereto; and a processing unit in communication with said detector, wherein said external-cavity frequency-tuned laser is substantially continuously tunable, wherein said tunable wavelength selecting device tunes the center wavelength of the external-cavity frequency-tuned laser at the same rate as the longitudinal cavity mode of the external-cavity frequency-tuned laser is tuned, and wherein said processing unit performs digital signal processing to extract spatial information related to the sample in response to said signal from said detector.
Claim 2
Dependent Claim 211 words
An optical system comprising: an external-cavity frequency-tuned laser having a tunable longitudinal cavity mode and a center timable wavelength, said external-cavity frequency-tuned laser comprising: an optical cavity; an optical gain medium positioned within said optical cavity; and a rapid tuning wavelength selecting device positioned to receive light from said optical gain medium and adapted to return selected wavelengths of light to said optical gain medium; an interferometer in optical communication with said external-cavity frequency-tuned laser, said interferometer adapted to project a portion of light from said external-cavity frequency-tuned laser onto a sample and to receive light altered by said sample, said interferometer adapted to combine light reflected from said sample and said light from said external-cavity frequency-tuned laser; a detector positioned to receive said combined light from said interferometer and to generate a signal in response thereto; and a processing unit in communication with said detector, wherein said external-cavity frequency-tuned laser is substantially continuously tunable, wherein said tunable wavelength selecting device tunes the center wavelength of the external-cavity frequency-tuned laser at the same rate as the longitudinal cavity mode of the external-cavity frequency-tuned laser is tuned, and wherein said processing unit performs digital signal processing to extract spatial information related to the sample in response to said signal from said detector.
Claim 3
Dependent Claim 18 words
The system of claim 1 wherein said wavelength selecting device comprises a grating and an angular scanning device.
Claim 4
Dependent Claim 15 words
The system of claim 2 wherein said angular scanning device comprises an electro-optical beam deflector.
Claim 5
Dependent Claim 14 words
The system of claim 2 wherein said angular scanning device comprises a rotatable prism.
Claim 6
Dependent Claim 15 words
The system of claim 2 wherein said angular scanning device comprises a galvanometer scanned mirror.
Claim 7
Dependent Claim 15 words
The system of claim 2 wherein said angular scanning device comprises a resonant scanning mechanism.
Claim 8
Dependent Claim 20 words
The system of claim 2 wherein said angular scanning device scans so as to generate a temporally non-linear frequency sweep.
Claim 9
Dependent Claim 60 words
The system of claim 7 further comprising: an auxiliary interferometer in optical communication with said external-cavity frequency-tuned laser, said auxiliary interferometer having an auxiliary detector in electrical communication with said processing unit, wherein data collected in response to said temporally non-linear frequency sweep are corrected by said processing unit in response to signals from said detector of said auxiliary interferometer.
Claim 10
Dependent Claim 13 words
The system of claim 7 wherein said temporally non-linear frequency sweep is sinusoidal.
Claim 11
Dependent Claim 29 words
The system of claim 7 wherein data collected in response to said temporally non-linear frequency sweep are corrected by said processing unit in response to signals from said detector.
Claim 12
Dependent Claim 40 words
The system of claim 2, wherein said scanner includes a drive mechanism whose drive function is pre-distorted in time to precorrect for any nonlinerarity in the laser transfer function so as to achieve a nearly continuous frequency sweep in time.
Claim 13
Dependent Claim 14 words
The system of claim 1 wherein said wavelength selecting device comprises tunable optical filter.
Claim 14
Dependent Claim 14 words
The external-cavity laser of claim 12, wherein said wavelength selecting device comprises an AOTF.

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EP0469259A2 Cited
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