Signal extraction systems and methods

Patent metadata

Field	Value
Publication number	US-10119803-B2
Application number	US-201615342418-A
Country	US
Kind code	B2
Filing date	Nov 3, 2016
Priority date	Nov 3, 2015
Publication date	Nov 6, 2018
Grant date	Nov 6, 2018

Abstract

Swept source optical coherence tomography (SS-OCT) systems and methods may employ down-conversion. Down-converter systems and methods may utilize a distribution element and a frequency down shifter. The distribution element may receive an output signal of a photo detection device, the output signal comprising a first frequency component at or below a maximum conversion frequency and a second frequency component above the maximum conversion frequency. The distribution element may send the first frequency component to an analog to digital (A/D) converter and send the second frequency component to a frequency down shifter. The frequency down shifter may down shift the second frequency component to a frequency at or below the maximum conversion frequency to form a down shifted second frequency component. The frequency down shifter may send the down shifted second frequency component to the A/D converter.

First claim

What is claimed is:

1. A swept source optical coherence tomography (SS-OCT) system comprising a down-converter system, the down converter system comprising:
a distribution element configured to:
receive an electrical output signal of a photo detection device, the electrical output signal comprising a first frequency component at or below a maximum conversion frequency and a second frequency component above the maximum conversion frequency;
send the first frequency component of the electrical output signal to an analog to digital (A/D) converter; and
send the second frequency component of the electrical output signal to a frequency down shifter; and

the frequency down shifter configured to:
down shift the second frequency component of the electrical output signal to a frequency at or below the maximum conversion frequency to form a down shifted second frequency component of the electrical output signal; and
send the down shifted second frequency component of the electrical output signal to the A/D converter.

2. The system of claim 1 , further comprising a low noise amplifier coupled to the distribution element and configured to:
receive an unfiltered electrical output signal of the photo detection device;
filter the unfiltered electrical output signal to generate the electrical output signal; and
send the electrical output signal to the distribution element.

3. The system of claim 1 , wherein the distribution element is configured to receive the electrical output signal directly from the photo detection device.

4. The system of claim 1 , wherein the distribution element comprises a switch configured to:
switch to a first output to pass the first frequency component of the electrical output signal to the A/D converter during a first scan; and
switch to a second output to pass the second frequency component of the electrical output signal to the frequency down shifter during a second scan.

5. The system of claim 4 , further comprising a bandpass filter or a highpass filter coupled between the second output of the switch and an input of the frequency down shifter.

6. The system of claim 4 , further comprising a second switch coupled to the first output of the switch and an output of the frequency down shifter, the second switch being configured to send an output of the second switch to the A/D converter.

7. The system of claim 4 , further comprising a buffer amplifier interposed between the A/D converter on an output side and the switch and the frequency down shifter on an input side.

8. The system of claim 1 , wherein the distribution element comprises a splitter configured to substantially simultaneously send the electrical output signal to the A/D converter and to the frequency down shifter.

9. The system of claim 8 , wherein the splitter is an RF power splitter.

10. The system of claim 8 , further comprising a bandpass filter or a lowpass filter coupled between an output of the splitter and an input of the A/D converter.

11. The system of claim 8 , further comprising a bandpass filter or a highpass filter coupled between an output of the splitter and an input of the frequency down shifter.

12. The system of claim 8 , wherein:
the A/D converter comprises a plurality of separate A/D converter devices; and
one of the A/D converter devices to which the down shifted second frequency component of the electrical output signal is sent is separate from another one of the A/D converter devices to which the first frequency component of the electrical output signal is sent.

13. The system of claim 1 , further comprising a plurality of filters, wherein:
the A/D converter comprises a plurality of separate A/D converter devices;
the frequency down shifter comprises a plurality of separate frequency down shifter devices;
the distribution element comprises a splitter configured to substantially simultaneously send the electrical output signal to each of the plurality of filters;
at least one of the filters comprises a lowpass filter or a bandpass filter coupled between a first output of the splitter and an input of a first one of the A/D converter devices;
at least two of the filters comprise a highpass filter or a bandpass filter, each of the at least two filters being coupled between a separate output of the splitter and a separate one of the frequency down shifter devices; and
each separate frequency down shifter comprises an output coupled to a another one of the A/D converter devices.

14. The system of claim 13 , wherein the splitter is an RF power splitter.

15. The system of claim 13 , wherein each separate frequency down shifter is configured to shift a separate portion of the second frequency component of the electrical output signal.

16. The system of claim 13 , wherein each of the filters is configured to pass a different portion of the electrical output signal.

17. The system of claim 1 , further comprising a plurality of filters, wherein:
the frequency down shifter comprises a plurality of separate frequency down shifter devices;
the distribution element comprises:
a first switch configured to sequentially send the electrical output signal to each of the plurality of filters; and
a second switch comprising an output coupled to the A/D converter;

at least one of the filters comprises a lowpass filter or a bandpass filter coupled between a first output of the first switch and a first input of the second switch;
at least two of the filters comprise a highpass filter or a bandpass filter, each of the at least two filters being coupled between a separate output of the first switch and a separate one of the frequency down shifter devices;
wherein each separate frequency down shifter device comprises an output coupled to a separate input of the second switch; and
wherein the second switch is configured to sequentially send a signal on each second switch input to the A/D converter.

18. The system of claim 17 , wherein each separate frequency down shifter device is configured to shift a separate portion of the second frequency component of the electrical output signal.

19. The system of claim 17 , wherein each of the filters is configured to pass a different portion of the electrical output signal.

20. The system of claim 1 , further comprising a plurality of filters, wherein:
the distribution element comprises:
a first switch configured to sequentially send the electrical output signal to each of the plurality of filters;
a second switch comprising:
a plurality of inputs each coupled to one of the plurality of filters; and
an output coupled to an input of the frequency down shifter; and

a third switch comprising:
a second input coupled to an output of the frequency down shifter; and
an output coupled to the A/D converter;

at least one of the filters comprises a lowpass filter or a bandpass filter coupled between a first output of the first switch and a first input of the third switch;
at least two of the filters comprise a highpass filter or a bandpass filter, each of the at least two filters being coupled between a separate output of the first switch and a separate input of the second switch;
the second switch is configured to sequentially send a signal on each second switch input to the frequency down shifter; and
the third switch is configured to sequentially send a signal on the first third switch input and a plurality of sequential signals on the second third switch input to the A/D converter.

21. The system of claim 20 , wherein each of t

Assignees

• Amo Wavefront Sciences Llc

Inventors

• Raymond Thomas D
• Neal Isaac
• Hamrick Daniel R
• Shay Thomas M

Classifications

• G01B9/02041

  characterised by particular imaging or detection techniques · CPC title

• G01B9/02004

  using frequency scans · CPC title

• G01B9/02083 Primary

  characterised by particular signal processing and presentation · CPC title

• A61B3/0025

  characterised by electronic signal processing, e.g. eye models · CPC title

• G01B9/02091

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