Methods and apparatus for phase stabilized swept-source optical coherence tomography (ss-oct) including rescaling and dynamic range enhancement

Abstract

An optical coherence tomography (OCT) system electrically mixes a signature signal with an OCT signal (e.g., an interferogram) output by a photodetector of the OCT system. The signature signal may be a signal output by a photodetector that detects an optical signal from a fiber Bragg grating. The signature signal may then be time delayed before combination with the OCT signal. A series of interferograms are then aligned according to the signature signal. A rescaling signal may be similarly electrically mixed with the signature and OCT signals.

What is claimed is: 
     
         1 . A method of imaging with an optical coherence tomography (OCT) system comprising:
 generating an analog electrical OCT signal by a detector, the analog electrical OCT signal being based on an interference signal of the OCT system detected by the detector;   attenuating the analog electrical OCT signal by passive electrical attenuation, thereby adjusting a dynamic range of the OCT system; and   digitizing the attenuated analog electrical OCT signal,   wherein the generated analog electrical OCT signal and the attenuated digital electrical OCT signal have substantially the same signal-to-noise ratio.   
     
     
         2 . The method of  claim 1 , wherein the attenuation is performed by a passive electrical attenuation circuit. 
     
     
         3 . The method of  claim 1 , further comprising:
 imaging a cornea of a subject with the OCT system to generate the interreference signal.   
     
     
         4 . The method of  claim 1 , wherein the attenuation is less than or equal to 15 dB. 
     
     
         5 . The method of  claim 1 , wherein the OCT system is a swept-source OCT system. 
     
     
         6 . A method of imaging with an optical coherence tomography (OCT) system comprising:
 analyzing a noise of the OCT system;   optimizing a gain of a detector of the OCT system based on the analyzed noise, thereby adjusting a dynamic range of the OCT system; and   generating an attenuated electrical OCT signal by the detector having the decreased gain, the attenuated electrical OCT signal being based on an interference signal of the OCT system detected by the detector, the   wherein decreasing the gain of the detector does not substantially affect a signal-to-noise ratio of the attenuated electrical OCT signal.   
     
     
         7 . The method of  claim 6 , further comprising:
 imaging a cornea of a subject with the OCT system to generate the interreference signal.   
     
     
         8 . The method of  claim 6 , wherein the decreased gain causes less than or equal to 15 dB of attenuation. 
     
     
         9 . The method of  claim 6 , wherein the noise is shot noise. 
     
     
         10 . The method of  claim 6 , wherein the noise is relative intensity noise. 
     
     
         11 . The method of  claim 6 , wherein the noise is noise from the detector. 
     
     
         12 . The method of  claim 6 , wherein the noise is a digitization noise caused by an analog-to-digital conversion of the attenuated electrical OCT signal. 
     
     
         13 . The method of  claim 6 , wherein optimizing the gain of a detector comprises decreasing the gain of the detector.