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US 7,456,957 B2Granted
Littrow spectrometer and a spectral domain optical coherence tomography system with a Littrow spectrometer
AssigneeCarl Zeiss Meditec AG
InventorsMatthew J. Everett, Yan Zhou, Jochen M. M. Horn, Keith O'Hara, James P. Foley
Life of this patent
Estimating the term…
Abstract
A compact conical diffraction Littrow spectrometer is disclosed. The distortion of the conically diffracted spectral component beams is compensated and as a result, the diffracted spectral beams can still be focused into a substantially straight line to shine onto a detector array. A spectral domain optical coherence tomography (SD-OCT) system incorporating a Littrow spectrometer or a spectrometer having one or more shared focusing element(s) and an SD-OCT system incorporating a spectrometer that is substantially polarization independent are also disclosed.
Claims51
A spectrometer for monitoring the magnitude of a broadband light beam as a function of wavelength comprising:
- a grating for angularly dispersing an incident light beam as a function of wavelength;
- a linear detector array for receiving and monitoring the dispersed light beam, with the incident beam, the grating and the detector array being positioned in a substantially Littrow condition and with the grating being tipped with respect to the incoming beam to induce conical diffraction to thereby spatially separate the path of the diffracted beam from the incident beam, with said conical diffraction resulting in the footprint of the dispersed light having a non-linearity in a direction perpendicular to the axis of the array;
- and
- a first optical element located between the grating and the array for reducing the non-linearity caused by the conical diffraction so the registration of the footprint with the array is improved.
1 more element
A spectrometer for monitoring the magnitude of a broadband light beam as a function of wavelength comprising:
- a grating for angularly dispersing an incident light beam as a function of wavelength;
- a linear detector array for receiving and monitoring the dispersed light beam and with the grating being tipped with respect to the incident beam to induce conical diffraction to thereby spatially separate the path of the diffracted beam from the incident beam, with said conical diffraction resulting in the footprint of the dispersed light having a non-linearity in a direction perpendicular to the axis of the array;
- and
- a first optical element located between the grating and the array and in the path of both the incident and the diffracted beam, said optical element for modifying the focus of the beam and for reducing the non-linearity caused by the conical diffraction so the registration of the footprint with the array is improved.
1 more element
A spectrometer for monitoring the magnitude of a broadband light beam as a function of wavelength comprising:
- a grating for angularly dispersing an incident light beam as a function of wavelength;
- a linear detector array for receiving and monitoring the dispersed light beam, with the incident beam, the grating and the detector array being positioned in a substantially Littrow condition and with the grating being tipped with respect to the incoming beam to induce conical diffraction to thereby spatially separate the path of the diffracted beam from the incident beam, with said conical diffraction resulting in the footprint of the dispersed light having a non-linearity in a direction perpendicular to the axis of the array;
- and
- means for reducing the non-linearity caused by the conical diffraction so the registration of the footprint with the array is improved.
1 more element
A spectral domain optical coherence tomography (OCT) system comprising:
- a broadband light source;
- a beam splitter for dividing the light along a sample and a reference path;
- a spectrometer for receiving light returned from both the sample and the reference paths, said spectrometer including a grating for angularly dispersing the light as a function of wavelength and a linear detector array for receiving and monitoring the dispersed light and with the path of the received light, the grating and the detector array being positioned in a substantially Littrow condition, and wherein the grating is tipped with respect to the received light to induce conical diffraction to thereby spatially separate the path of the dispersed light from the incident light with said conical diffraction resulting in the footprint of the dispersed light having a non-linearity in a direction perpendicular to the axis of the array and further including a means for reducing said non-linearities, said spectrometer for generating output signals as a function of wavelength;
- a processor for analyzing the output signals to derive a reflectance distribution along the sample path;
- an optical fiber having an output end for delivering the light to the spectrometer;
- and
- a lens positioned near the output end of the fiber to adjust the numerical aperture of the light exiting the fiber and entering the spectrometer.
4 more elements
A spectral domain optical coherence tomography (OCT) system comprising:
- a broadband light source;
- a beam splitter for dividing the light along a sample and a reference path;
- a spectrometer for receiving light returned from both the sample and the reference paths, said spectrometer including a grating for angularly dispersing the light as a function of wavelength and a linear detector array for receiving and monitoring the dispersed light and with the path of the received light, the grating and the detector array being positioned in a substantially Littrow condition, and wherein the grating is tipped with respect to the received light to induce conical diffraction to thereby spatially separate the path of the dispersed light from the incident light, with said conical diffraction resulting in the footprint of the dispersed light having a non-linearity in a direction perpendicular to the axis of the array, said spectrometer further including an optical element located between the grating and the array and in the path of both the received light and the dispersed light, said optical element for modifying the focus of the beam and for reducing the non-linearity caused by the conical diffraction so the registration of the footprint with the array is improved, said spectrometer for generating output signals as a function of wavelength;
- and
- a processor for analyzing the output signals to derive a reflectance distribution along the sample path.
2 more elements
A spectral domain optical coherence tomography (OCT) system comprising:
- a broadband light source;
- a beam splitter for dividing the light along a sample and a reference path;
- a spectrometer for receiving light returned from both the sample and the reference paths, said spectrometer including a grating for angularly dispersing the light as a function of wavelength and a linear detector array for receiving and monitoring the dispersed light and with the path of the received light, the grating and the detector array being positioned in a substantially Littrow condition, said spectrometer further including a first cylindrical lens rigidly mounted to and aligned with the detector array and a separate, second cylindrical lens for correcting the astigmatism created by the first cylindrical lens, said spectrometer for generating output signals as a function of wavelength;
- and
- a processor for analyzing the output signals to derive a reflectance distribution along the sample path.
2 more elements
A spectral domain optical coherence tomography (OCT) system comprising:
- a broadband light source;
- a beam splitter for dividing the light along a sample and a reference path;
- a spectrometer for receiving light returned from both the sample and the reference paths, said spectrometer including a grating for angularly dispersing the light as a function of wavelength and a linear detector array for receiving and monitoring the dispersed light and with the path of the received light, the grating and the detector array being positioned in a substantially Littrow condition, said spectrometer further including a vertically demagnifying light pipe with the de-magnified end of the light pipe being rigidly mounted to and aligned with the detector array and the opposing end of the light pipe being positioned to receive light diffracted from the grating, said spectrometer for generating output signals as a function of wavelength;
- and
- a processor for analyzing the output signals to derive a reflectance distribution along the sample path.
2 more elements
A spectral domain optical coherence tomography (OCT) system comprising:
- a broadband light source;
- a beam splitter for dividing the light along a sample and a reference path;
- a spectrometer for receiving light returned from both the sample and the reference paths, said spectrometer including a grating for angularly dispersing the light as a function of wavelength and a linear detector array for receiving and monitoring the dispersed light and with the path of the received light, the grating and the detector array being positioned in a substantially Littrow condition, and wherein the grating is tipped with respect to the received light to induce conical diffraction to thereby spatially separate the path of the dispersed light from the incident light with said conical diffraction resulting in the footprint of the dispersed light having a non-linearity in a direction perpendicular to the axis of the array and further including a means for reducing said non-linearities, said spectrometer for generating output signals as a function of wavelength;
- and
- a processor for analyzing the output signals to derive a reflectance distribution along the sample path.
2 more elements
Dependencies are inferred from the claim text.