Methods and apparatus for swept-source optical coherence tomography
AssigneeLightLab Imaging, Inc.
InventorJoseph M. Schmitt
Life of this patent
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Abstract
In one embodiment of the invention, a semiconductor optical amplifier (SOA) in a laser ring is chosen to provide low polarization-dependent gain (PDG) and a booster semiconductor optical amplifier, outside of the ring, is chosen to provide high polarization-dependent gain. The use of a semiconductor optical amplifier with low polarization-dependent gain nearly eliminates variations in the polarization state of the light at the output of the laser, but does not eliminate the intra-sweep variations in the polarization state at the output of the laser, which can degrade the performance of the SS-OCT system.
Claims16
An apparatus for tunable filter linearization comprising:
- a mechanically actuated tunable filter;
- and
- a pair of phase-locked sine-wave generators having an output in electrical communication with the mechanically actuated tunable filter, wherein one of the pair of phase-locked sine wave generators operates at twice the frequency of the other of the pair of phase-locked sine wave generators.
A method for tunable filter linearization comprising the steps of:
- providing a mechanically actuated tunable filter;
- and
- generating an output signal from a pair of phase-locked sine-wave generators;
- and
- applying the generated output signal to the mechanically actuated tunable filter,
- wherein one of the pair of phase-locked sine-wave generators operates at twice the frequency of the other.
A method for tunable filter linearization comprising the steps of:
- choosing a fundamental frequency that avoids the mechanical resonance frequencies of a tunable filter;
- summing two or three harmonically related sinusoids of the fundamental frequency;
- and
- tuning the amplitudes and phases of the summed sinusoids to compensate for non-uniformities in amplitude and phase responses of the tunable filter.
A linearized tunable filter comprising:
- a mechanically actuated tunable filter having a resonance frequency;
- and
- a linearization module in electrical communication with the mechanically actuated tunable filter, the linearization module:
- generates a fundamental frequency that avoids the mechanical resonance frequencies of the tunable filter;
- sums two or three harmonically related sinusoids of the fundamental frequency;
- and
- generates amplitudes and phases of the summed sine waves to compensate for non-uniformities in the amplitude and phase responses of tunable filter.
Dependencies are inferred from the claim text.