Spectral filtering of k-clock signal in OCT system and method
View Patent ↗A system and method for spectral filtering of a k-clock signal in a swept-source Optical Coherence Tomography (“OCT”) system to remove artifacts in the k-clock signal. The system synchronizes sampling of the k-clock and interference signals generated from scanning a sample. Using a filtered k-clock signal, the system resamples an interference dataset of the interference signals. The system then performs Fourier transform based processing upon the resampled interference dataset to yield axial depth images of the sample. The system preferably performs the reconstruction, resampling, and associated Fourier-Domain signal processing in software via a Field Programmable Gate Array (“FPGA”) of a rendering system.
1. An optical coherence analysis system, comprising:
an optical swept source system that generates a swept optical signal;
a k-clock module that generates k-clock signals in response to frequency sweeping of the swept optical signal;
an interferometer that generates interference signals from the swept optical signal;
a data acquisition system that samples the k-clock signals and the interference signals to generate a k-clock dataset and an interference dataset; and
a rendering system that spectrally filters the k-clock dataset into a reconstructed k-clock dataset, and resamples the interference dataset into a linearized interference dataset in response to the reconstructed k-clock dataset.
2. The optical coherence analysis system of claim 1 , wherein the rendering system resamples the interference dataset into the linearized interference dataset in response to a reconstructed k-clock dataset.
3. The optical coherence analysis system of claim 1 , wherein the rendering system comprises a field-programmable gate array that implements a spectral filter for converting the k-clock dataset into the reconstructed k-clock dataset.
4. The optical coherence analysis system of claim 1 , wherein the rendering system identifies tuning jitter artifacts in the k-clock dataset.
5. The optical coherence analysis system of claim 1 , wherein the rendering system spectrally filters the k-clock dataset by bandpass filtering the k-clock dataset to suppress artifacts using a k-clock bandpass window for creating the reconstructed k-clock dataset.
6. The optical coherence analysis system of claim 5 , wherein the k-clock bandpass window is bounded by a lower frequency value of the k-clock dataset, and an upper frequency value of the k-clock dataset.
7. The optical coherence analysis system of claim 6 , wherein the k-clock bandpass window is bounded by a frequency value of a lower sideband of the k-clock dataset, and a frequency value of an upper sideband of the k-clock dataset.
8. The optical coherence analysis system of claim 1 , wherein the rendering system spectrally filters the k-clock dataset by:
performing a Fourier transform upon the k-clock dataset; and
performing an inverse Fourier transform to create the reconstructed k-clock dataset.
9. The optical coherence analysis system of claim 8 , wherein the rendering system applies values of a bandpass function to frequency values outside of a k-clock bandpass filter window prior to performing the inverse Fourier transform.
10. The optical coherence analysis system of claim 9 , wherein the rendering system applies zeros to frequency values outside of a k-clock bandpass filter window prior to performing the inverse Fourier transform.
11. The optical coherence analysis system of claim 1 , wherein the data acquisition system samples the k-clock signals and the interference signals at a fixed signal sampling rate for generating the k-clock dataset and the interference dataset.
12. The optical coherence analysis system of claim 1 , wherein the rendering system comprises a field programmable gate array for creating the linearized interference dataset in response to the reconstructed k-clock dataset.
13. An optical coherence analysis method, comprising:
generating a swept optical signal;
generating k-clock signals in response to frequency sweeping of the swept optical signal;
generating interference signals from the swept optical signal;
sampling the k-clock signals and the interference signals to generate a k-clock dataset and an interference dataset; and
spectrally filtering the k-clock dataset into a reconstructed k-clock dataset, and the resampling the interference dataset into a linearized interference dataset in response to the reconstructed k-clock dataset.
14. The optical coherence analysis method of claim 13 , further comprising resampling the interference dataset into the linearized interference dataset in response to a reconstructed k-clock dataset.
15. The optical coherence analysis method of claim 13 , further comprising applying a spectral filter for converting the k-clock dataset into the reconstructed k-clock dataset.
16. The optical coherence analysis method of claim 13 , further comprising preserving tuning jitter information in the reconstructed k-clock dataset.
17. The optical coherence analysis method of claim 13 , further comprising spectrally filtering the k-clock dataset by bandpass filtering the k-clock dataset to suppress artifacts using a k-clock bandpass window for creating the reconstructed k-clock dataset.
18. The optical coherence analysis method of claim 17 , wherein the k-clock bandpass window is bounded by a lower frequency value of the k-clock dataset, and an upper frequency value of the k-clock dataset.
19. The optical coherence analysis method of claim 17 , wherein the k-clock bandpass window is bounded by a frequency value of a lower sideband of the k-clock dataset, and a frequency value of an upper sideband of the k-clock dataset.
20. The optical coherence analysis method of claim 13 , further comprising
performing a Fourier transform upon the k-clock dataset; and
performing an inverse Fourier transform to create the reconstructed k-clock dataset.