Granted Patent B2

US 8,994,954 · App. 13/729,587 · Granted Mar 31, 2015

Abstract

Claims (31)

1. An optical coherence imaging method, comprising:

providing a laser swept source to generate a swept optical signal;

modulating a drive signal for a gain element as the swept optical signal is swept through a scan band by modulating a current to the gain element synchronously with and with the periodicity of a tunable element drive signal that is applied to a tunable element within a cavity of the laser swept source, which tunable element is used to control a wavelength of the swept optical signal, to control a mode-locked operation of the laser swept source;

transmitting the swept optical signal to an interferometer having a reference arm and a sample arm, in which a sample is located;

combining the swept optical signal returning from the sample arm and the reference arm to generate an interference signal;

detecting the interference signal; and

generating image information of the sample from the detected interference signal.

2. An optical coherence analysis system comprising:

a swept laser source for generating a swept optical signal that is frequency tuned over a scan band, including a gain element for amplifying light within a laser cavity of the swept laser source to generate the swept optical signal and a tuning element for controlling a frequency of the swept optical signal to sweep across the scan band;

a controller for modulating a current signal for the gain element as the swept optical signal is swept through the scan band synchronously with and with the periodicity of a tuning element drive signal to the tuning element within the laser cavity of the laser swept source, to control a mode-locked operation of the laser swept source;

an interferometer for dividing the swept optical signal between a reference arm and a sample arm leading to a sample; and

a detector system for detecting an interference signal generated from the swept optical signal from the reference arm and from the sample arm.

3. A method as claimed in claim 1 , further comprising:

generating a stability map as a function of wavelength for the laser swept source; and

modulating the current to the gain element based on the stability map.

4. A method as claimed in claim 1 , wherein the laser swept source tunes at greater than 5 nanometers per microsecond.

5. A method as claimed in claim 1 , wherein the scan band is greater than 50 nanometers.

6. A method as claimed in claim 1 , further comprising a controller storing a gain element drive waveform that defines the current to the gain element for the sweep through the scan band.

7. A method as claimed in claim 6 , further comprising synchronizing the gain element drive waveform with a filter drive waveform that defines the tunable element drive signal for the sweep through the scan band.

8. A method as claimed in claim 1 , wherein the tunable optical element is a Fabry-Perot tunable filter.

9. An optical coherence analysis system comprising:

a swept laser source for generating a swept optical signal that is frequency tuned over a tuning band, including a gain medium for amplifying light within a laser cavity of the swept laser source to generate the swept optical signal and a tuning element for controlling a frequency of the swept optical signal to sweep across a scanband;

a controller for modulating a drive signal for the gain element as the swept optical signal is swept through the scan band synchronously with a tuning element drive signal to the tuning element;

an interferometer for dividing the swept optical signal between a reference arm and a sample arm leading to a sample; and

a detector system for detecting an interference signal generated from the swept optical signal from the reference arm and from the sample arm.

10. A system as claimed in claim 9 , wherein the controller controls the mode-locked operation of the swept laser source by modulating bias current to the gain medium, which is a semiconductor optical amplifier.

11. A system as claimed in claim 9 , wherein the laser swept source tunes at greater than 5 nanometers per microsecond.

12. A system as claimed in claim 9 , wherein the scan band is greater than 50 nanometers.

13. A system as claimed in claim 9 , wherein the controller stores a gain element drive waveform that defines the current signal for the gain element for the sweep through the scan band.

14. A system as claimed in claim 13 , wherein the controller synchronizes the gain element drive waveform with a filter drive waveform that defines the tuning element drive signal for the sweep through the scan band.

15. A system as claimed in claim 9 , wherein the tuning element is a Fabry-Perot tunable filter.

Assignments (9)