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US 8,913,248 B2Granted
Systems and methods for improved balanced detection in optical coherence tomography imaging
AssigneeCarl Zeiss Meditec AG
InventorsUtkarsh Sharma, Lingfeng Yu, Alexandre R. Tumlinson, Matthew J. Everett
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Abstract
Systems and methods for reducing noise in balanced detection based optical coherence tomography (OCT) systems are described. Embodiments including both optical hardware and electronic based solutions to spectrally filter and attenuate the source reference light in optical coherence tomography in an effort to reduce RIN and FPN noise in OCT systems are presented. A novel application to electronic balanced detection schemes in which a single source of reference detection is balanced against the interferometric signals from multiple interferometers is also presented.
Claims31
An optical coherence tomography (OCT) system, the system comprising:
- a light source arranged to generate a beam of radiation wherein the wavelength of the beam varies over time;
- a balanced detector with at least first and second photodetectors for acquiring data;
- at least one coupler functioning to direct a first portion of the beam to a sample and to direct a second portion of the beam to a reference arm, and for causing the light from the reference arm and the light reflected from the sample to be combined and for directing a portion of the combined light to the first photodetector and for directing a portion of one of the combined light, the source light, or light returning from the reference arm to the second photodetector and wherein the splitting ratio of the coupler varies as a function of the wavelength of the beam;
- and
- a means for compensating for the spectral dependence of the coupler to spectrally balance the light falling on the first and second photodetectors prior to data acquisition.
2 more elements
An optical coherence tomography (OCT) system, the system comprising:
- a light source for generating a beam of radiation that is swept in wavelength over time;
- a first, non-directional coupler having a first coupling ratio (γ1 /(1−γ1)) functioning to divide the beam into two portions of unequal optical powers where γ is a power splitting fraction;
- a balanced detector with at least first and second photodetectors for acquiring data;
- and
- optical components functioning to direct the portion of the beam of lesser optical power from the first coupler to a second non-directional coupler having a second coupling ratio (γ2 /(1−γ2)) that divides the received portion of the beam into sample and reference arms and divides the light returning from the sample and reference arms into two portions of unequal optical powers, wherein one portion is directed back to the first coupler and the other portion is directed to the first photodetector and wherein the first coupler directs a portion of the reflected light to the second photodetector and wherein the coupling ratios of the two couplers satisfy the following condition (1-γ2)*γ1=γ2 whereby the power from the reference arm supplied to both the first and second photodetectors is equal for at least one of the wavelengths in the central portion of the wavelength sweep.
2 more elements
An optical coherence tomography (OCT) system, said OCT system comprising:
- a light source arranged to generate a beam of radiation wherein the wavelength of the beam varies over time;
- a beam divider for separating the beam along a sample arm and a reference arm, wherein the splitting ratio of the divider varies as a function of the wavelength of the beam;
- a detector for measuring radiation returning from both the sample arm and the reference arm, the detector generating output signals in response thereto, wherein said detector has at least two photodetectors connected in series at a common node to provide balanced detection, said detector further including a waveform generator having an output connected between one of the photodetectors and the common node to modify the splitting ratio between the photodetectors as the wavelength of the source is varied in order to compensate for the spectral dependence of the divider, wherein the waveform is generated based on stored calibration information.
An optical coherence tomography (OCT) system, the system comprising:
- a light source arranged to generate a beam of radiation;
- a divider for directing the beam towards at least two interferometers each having its own sample arm;
- optics for combining light from at least one reference arm with sample light from each of the multiple interferometers;
- a detector for measuring the combined light from the multiple interferometers, the detector generating output signals in response thereto, wherein said detector has at least three photodetectors, wherein one of the photodetectors receives only source light and does not receive sample light and at least two of the photodetectors receive light from different interferometers, and wherein the step of generating a balanced output includes subtracting the signal from the photodetector with only source light from the signals at the photodetectors with light from multiple interferometers.
1 more element
Dependencies are inferred from the claim text.