Apparatus and methods for uniform frequency sample clocking
First Claim
1. A clocking method for optical coherence tomography, comprising the steps of coupling a swept source to a uniform frequency sample clock pathway and characterizing the swept source, creating a digital representation of a clocking signal by the characterizing step, and generating the clocking signal as an output to a digitizer'"'"'s external clock input to provide linear sampling for direct Fourier transformation into the pathlength domain.
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Abstract
A method and a system for Uniform Frequency Sample Clocking to directly sample the OCT signal with a temporally-non-linear sampling clock derived from a k-space wavemeter on the external sample clock input port of a digitizer. The Uniform Frequency Sample Clocking comprises at least one Pathway, which includes characterizing the swept light source, creating a digital representation of the waveform based from the characterization data, and generating a clock signal using a waveform generator to output the clock signal to a digitizer external clock.
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Citations
19 Claims
- 1. A clocking method for optical coherence tomography, comprising the steps of coupling a swept source to a uniform frequency sample clock pathway and characterizing the swept source, creating a digital representation of a clocking signal by the characterizing step, and generating the clocking signal as an output to a digitizer'"'"'s external clock input to provide linear sampling for direct Fourier transformation into the pathlength domain.
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17. A system for uniform frequency sample clocking comprising:
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a sampling circuit including an external sample clock signal from an auxiliary wavemeter during the limited duty cycle of a tunable source and a pre-locked voltage controlled oscillator during the non-sweeping segment of each duty cycle including a locked voltage; a phase locked loop to sync the voltage controlled oscillator output with the auxiliary wavemeter output, at which time the external sample clock is switched from the optical wavemeter output to the output of the voltage controlled oscillator, wherein the locked voltage is regained when the swept source begins to sweep and the output is switched to a k-space auxiliary wavemeter output.
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18. An optical coherence tomographic system comprising:
- a swept light source including a plurality of fiber optic couplers to subdivide the swept light source into a primary optical coherence tomographic interferometer, and a uniform frequency sample clock pathway to generate a clock signal allowing an acquisition of the optical coherence tomographic signal data directly in the wavenumber (k) space, wherein the uniform frequency sample clock pathway comprises an auxiliary wavemeter, and an optical trigger generator;
a digitizer coupled to the photoreceiver from the primary optical coherence tomographic interferometer and the photoreceiver from the auxiliary wavemeter;
wherein the external clock derived from the auxiliary wavemeter is regenerated by an arbitrary waveform generator to allow the acquisition of optical coherence tomographic signal data directly in the wavenumber (k) space.
- a swept light source including a plurality of fiber optic couplers to subdivide the swept light source into a primary optical coherence tomographic interferometer, and a uniform frequency sample clock pathway to generate a clock signal allowing an acquisition of the optical coherence tomographic signal data directly in the wavenumber (k) space, wherein the uniform frequency sample clock pathway comprises an auxiliary wavemeter, and an optical trigger generator;
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19. An optical coherence tomographic system comprising:
- a swept light source including a plurality of fiber optic couplers to subdivide the swept light source into a primary optical coherence tomographic interferometer, and a uniform frequency sample clock pathway to generate a clock signal allowing an acquisition of the optical coherence tomographic signal data directly in the wavenumber (k) space, wherein the uniform frequency sample clock pathway comprises a signal interferometer, a reference interferometer, a clocking interferometer, and a spectrally fixed trigger,
the interference fringe of the single interferometer and the interference fringe of the reference interferometer are coupled to a digitizer; the interference fringe of the clocking interferometer is coupled to an analog processor to serve as the external clock signal; and spectrally fixed trigger includes a gas cell and single detector, wherein the gas cell forms at least one narrowband TTL pulse and the pulse is selected using a time window produced by the single channel detector to serve as the spectrally fixed trigger for the digitizer.
- a swept light source including a plurality of fiber optic couplers to subdivide the swept light source into a primary optical coherence tomographic interferometer, and a uniform frequency sample clock pathway to generate a clock signal allowing an acquisition of the optical coherence tomographic signal data directly in the wavenumber (k) space, wherein the uniform frequency sample clock pathway comprises a signal interferometer, a reference interferometer, a clocking interferometer, and a spectrally fixed trigger,
Specification