Optical coherence tomography control systems and methods

Patent metadata

Field	Value
Publication number	US-9417052-B2
Application number	US-201414160939-A
Country	US
Kind code	B2
Filing date	Jan 22, 2014
Priority date	Aug 31, 2012
Publication date	Aug 16, 2016
Grant date	Aug 16, 2016

Abstract

In part, the invention relates to methods, devices, and systems suitable for controlling a light source. The light source is configured for use in a data collection system such as an optical coherence tomography system. The light source can be controlled with a drive waveform. Linearizing and symmetrizing parameters of the light source such as forward and backward scan durations is achieved using a suitable drive waveform. Phase, amplitude, and other parameters for different harmonics of a fundamental wave can be identified that improve operating parameters such as the duty cycle and peak frequency matching between scans. The fundamental wave and one or more of such harmonics can be combined to generate the suitable drive wave form. The light source can include a tunable light source that includes or is in optical communication with a tunable filter.

First claim

What is claimed is:

1. An optical coherence tomography system comprising
a drive waveform source comprising a memory, an output, and one or more function generators configured to (a) generate a first harmonic wave, (b) generate a second harmonic wave (c) generate a third harmonic wave; and (d) combine the first, second, and third harmonic waves such that a drive waveform is generated and stored in the memory, the drive waveform configured to cause a sweep response in a forward scan direction of the light source and a sweep response in a backward scan direction of the light source to be substantially symmetric and substantially linearize a sweep response of the light source; and
a light source comprising a tunable filter having an asymmetric sweep response, the tunable filter in electrical communication with the output and configured to receive the drive waveform from the output, wherein the second harmonic wave has a first phase value configured to cause a peak RF frequency for a backward scan of the tunable filter and a peak RF frequency for a forward scan of the tunable filter to differ by less than about 15%.

2. The system of claim 1 wherein the drive waveform source is a control system, a processor or a circuit.

3. The system of claim 1 wherein the light source is a laser.

4. The system of claim 3 wherein the tunable filter is a MEMS tunable filter.

5. The system of claim 3 the tunable filter is a piezoelectric tunable filter.

6. The system of claim 3 wherein the third harmonic wave has a second phase value configured to reduce or minimize a peak RF OCT signal frequency for a backward scan and a forward scan of the tunable filter.

7. The system of claim 3 wherein the third harmonic wave has a first amplitude value configured to reduce or minimize a peak RF OCT signal frequency for a backward scan and a forward scan of the tunable filter.

8. The system of claim 1 wherein the first phase value is generated by searching for an extremum in a two dimensional space that includes forward and backward scan data measured with respect to the light source as the tunable filter is swept.

9. The system of claim 1 wherein the first amplitude value is generated by searching for an extremum in a two dimensional space that includes forward and backward scan data measured with respect to the light source as the tunable filter is swept.

10. The system of claim 3 wherein an effective duty cycle of the laser is greater than about 90% of a sweep period of the light source when collecting OCT data.

11. The system of claim 3 wherein a forward scan duration of the tunable filter is about equal to a backward scan duration of the tunable filter.

12. The system of claim 1 wherein a ratio of a forward scan duration to a backward scan duration ranges from about 0.8 to about 1.2 when the drive waveform is applied to the tunable filter.

13. The system of claim 1 wherein a ratio of a peak RF fringe frequency during a forward scan to a peak RF fringe frequency during a backward scan duration ranges from about 0.9 to about 1.1 when the drive waveform is applied to the tunable filter.

14. The system of claim 1 wherein a sweep response in a forward scan direction of the light source and a sweep response in a backward scan direction of the light source is substantially symmetric when the tunable filter receives the drive waveform.

15. The system of claim 9 wherein the two dimensional space is an amplitude and phase space.

16. An optical coherence tomography system comprising:
a swept light source comprising a tunable filter comprising an input, the tunable filter in optical communication with a sample arm of an interferometer, wherein the tunable filter is drivable bidirectionally and has an asymmetric sweep response;
a control system comprising a non-transitory memory and an output, wherein the output is in electrical communication with the input, the control system configured to drive the tunable filter in one or more directions; and
a drive waveform stored in the non-transitory memory, the drive waveform configured to cause a sweep response in a forward scan direction of the light source and a sweep response in a backward scan direction of the swept light source to be substantially symmetric and substantially linearize a sweep response of the light source, wherein an effective duty cycle of the swept light source is greater than about 90% of a sweep period of the swept light source when collecting optical coherence tomography data.

17. The system of claim 16 wherein a ratio of a forward scan duration to a backward scan duration ranges from about 0.8 to about 1.2 when the drive waveform is applied to the tunable filter.

18. The system of claim 16 wherein a ratio of a peak RF fringe frequency during a forward scan to a peak RF fringe frequency during a backward scan duration ranges from about 0.9 to about 1.1 when the drive waveform is applied to the tunable filter.

19. The system of claim 16 wherein a forward scan duration of the tunable filter is about equal to a backward scan duration of the tunable filter.

20. The system of claim 16 wherein a sweep response in a forward scan direction of the swept light source and a sweep response in a backward scan direction of the swept light source is substantially symmetric when the tunable filter receives the drive waveform.

21. The system of claim 16 wherein the stored drive waveform is generated by superimposing two or more harmonic waves, the two or more harmonic waves defined using a phase value and an amplitude value.

22. The system of claim 21 wherein the phase value is selected to reduce or minimize a peak RF OCT signal frequency for a backward scan and a forward scan of the tunable filter.

23. The system of claim 21 wherein the amplitude value is selected to reduce or minimize a peak RF OCT signal frequency for a backward scan and a forward scan of the tunable filter.

Assignees

• Adler Desmond
• Lightlab Imaging Inc

Inventors

• Adler Desmond

Classifications

• G01B9/02091 Primary

  Tomographic interferometers, e.g. based on optical coherence · CPC title

• A61B5/0066

  Optical coherence imaging · CPC title

• H01S5/183

  having only vertical cavities, e.g. vertical cavity surface-emitting lasers [VCSEL] · CPC title

• A61B5/0084

  for introduction into the body, e.g. by catheters (A61B5/1459 takes precedence) · CPC title

• H01S3/1396

  by using two modes present, e.g. Zeeman splitting (H01S3/1398 takes precedence) · CPC title