Apparatus and methods to enhance signal to noise ratio imaging performance in optical coherence tomography
An optical coherence tomography system which is capable of operating in two or more optical bandwidth configurations for the purpose of trading off between high resolution imaging and high signal-to-noise ratio imaging, wherein the later enables deeper imaging depth. The system and associated methods allow for both high resolution, shallow penetration depth and low resolution, deep penetration depth optical coherence tomography imaging to be performed using a single light source. Methods and apparatus are described that allow a single system to dynamically switch between modes, or to operate in a hybrid mode that achieves a balance between resolution and SNR/depth of penetration.
1 . An optical coherence tomography (OCT) system, comprising:
a light source configured to provide a first illumination and a second illumination to a diffuse scattering sample,
the first illumination providing light within a first bandwidth and the second illumination providing light within a second bandwidth narrower than the first bandwidth;
an OCT optical arrangement comprising a sample light path and a reference light path, each of which is optically coupled to the light source to generate interference data from the sample;
a detector optically coupled to the OCT optical arrangement and configured to collect the interference data from the sample; and
a controller configured to:
switch illumination provided to the OCT optical arrangement between the first illumination and the second illumination,
the interference data comprising first interference data obtained using the first illumination and second interference data obtained using the second illumination,
determine a first signal-to-noise ratio (SNR) of the first interference data and a second SNR of the second interference data,
wherein the second SNR is greater than the first SNR, and
collect, based on the second SNR being greater than the first SNR, images from a second depth within the sample using the second illumination and from a first depth using the first illumination, wherein the second depth is greater than the first depth.
2 . The system of claim 1 , wherein the controller is configured to determine a first axial resolution of the first interference data and a second axial resolution of the second interference data,
wherein the first axial resolution is smaller than the second axial resolution.
3 . The system of claim 1 , wherein a ratio of the second bandwidth to the first bandwidth is 0.5 or less.
4 . The system of claim 1 , wherein a ratio of the second bandwidth to the first bandwidth is 0.25 or less.
5 . The system of claim 1 , wherein a ratio of the second bandwidth to the first bandwidth is 0.1 or less.
6 . The system of claim 1 , wherein at least one of the first bandwidth or the second bandwidth is determined based on determining at least one of a full-width and half-maximum (FWHM) of a power spectral density, a root mean square (RMS) bandwidth, or a total edge-to-edge optical bandwidth of a useable imaging light of the light source.
7 . The system of claim 1 , wherein the light source emits the first illumination during a first time period and the second illumination during a second time period different from the first time period.
8 . The system of claim 7 , wherein the light source comprises at least one of a swept source, a comb source, or a stepped source, and
wherein the first bandwidth or the second bandwidth is determined based on determining an edge-to-edge optical bandwidth of a useable imaging light of the light source.
9 . The system of claim 7 , wherein the detector is configured to collect the interference data from the sample as a function of time.
10 . The system of claim 9 , wherein the detector comprises at least one of a single-ended detector or a balanced detector.
11 . The system of claim 1 , wherein the light source comprises a first light source configured to provide the first illumination and a second light source configured to provide the second illumination, and
wherein the controller is configured to switch between transmitting the first illumination to the sample from the first light source and the second illumination to the sample from the second light source.
12 . The system of claim 11 , wherein at least one of the first light source or the second light source comprises a broadband light source.
13 . The system of claim 12 , wherein the detector is configured to collect the interference data from the sample as a function of wavelength.
14 . The system of claim 13 , wherein the detector comprises a spectrometer.
15 . The system of claim 1 , wherein a first lateral resolution of the first interference data is equal to a second lateral resolution of the second interference data.
16 . An optical coherence tomography (OCT) system, comprising:
a light source configured to provide a first illumination and a second illumination to a diffuse scattering sample,
the first illumination providing light within a first bandwidth and the second illumination providing light within a second bandwidth narrower than the first bandwidth;
an OCT optical arrangement comprising a sample light path and a reference light path, each of which is optically coupled to the light source to generate interference data from the sample;
a detector comprising a spectrometer optically coupled to the OCT optical arrangement and configured to collect the interference data from the sample as a function of wavelength; and
a controller configured to:
switch illumination provided to the OCT optical arrangement between the first illumination and the second illumination,
the interference data comprising first interference data obtained using the first illumination and second interference data obtained using the second illumination, and
a ratio of the first bandwidth to the second bandwidth being at least 2,
determine a first signal-to-noise ratio (SNR) of the first interference data and a second SNR of the second interference data,
wherein the second SNR is greater than the first SNR, and
collect, based on the second SNR being greater than the first SNR, images from a second depth within the sample using the second illumination and from a first depth using the first illumination, wherein the second depth is greater than the first depth.
17 . An optical coherence tomography (OCT) system, comprising:
a light source configured to provide a first illumination and a second illumination to a diffuse scattering sample,
the first illumination providing light within a first bandwidth comprising a first wavelength vs. time profile and a first power vs. time profile, and
the second illumination providing light within a second bandwidth narrower than the first bandwidth, the second illumination comprising a second wavelength vs. time profile and a second power vs. time profile;
an OCT optical arrangement comprising a sample light path and a reference light path, each of which is optically coupled to the light source to generate interference data from the sample;
a detector optically coupled to the OCT optical arrangement and configured to collect the interference data from the sample; and
a controller configured to:
control the light source to switch illumination provided to the OCT optical arrangement between the first illumination and the second illumination by controlling at least one of the first wavelength vs. time profile or the first power vs. time profile of the first illumination and by controlling at least one of the second wavelength vs. time profile or the second power vs. time profile of the second illumination,
the interference data comprising first interference data obtained using the first illumination and second interference data obtained using the second illumination,
determine a first signal-to-noise ratio (SNR) of the first interference data and a second SNR of the second interference data,
wherein the second SNR is greater than the first SNR, and
collect, based on the second SNR being greater than the first SNR, images from a second depth within the sample using the second illumination and from a first depth using the first illumination, wherein the second depth is greater than the first depth.
18 . The system of claim 17 , wherein the controller is configured to control the light source to switch illumination provided to the OCT optical arrangement to provide a higher SNR or a smaller axial resolution based on controlling at least one of the first wavelength vs. time profile or the first power vs. time profile of the first illumination and by controlling at least one of the second wavelength vs. time profile or the second power vs. time profile of the second illumination.