Efficient interferometer designs for optical coherence tomography

Patent metadata

Field	Value
Publication number	US-9778020-B2
Application number	US-201615159601-A
Country	US
Kind code	B2
Filing date	May 19, 2016
Priority date	May 22, 2015
Publication date	Oct 3, 2017
Grant date	Oct 3, 2017

Abstract

Efficient interferometer designs for optical coherence tomography (OCT) systems are presented. One example interferometer design includes two polarization dependent beamsplitters and a non-polarization dependent combiner. The first polarization dependent beamsplitter transmits light in a first polarization state to a sample arm of the OCT system and transmits light in a second polarization state different from the first polarization state to a reference arm of the system. The second polarization dependent beamsplitter transmits light returning from a sample to the non-polarization dependent combiner. The combiner combines light returned from the sample and the light that has passed through the reference arm, which is then detected at a detector. Another example interferometer design includes free space optics comprising a non-reciprocal beamsplitting element in a beam path from a light source to a sample. The non-reciprocal beamsplitting element is implemented using a combination of a polarization dependent beamsplitter and a polarization manipulator.

First claim

What is claimed is:

1. An interferometer for use in an optical coherence tomography (OCT) imaging system, said system having a source arm with an optical radiation source, a sample arm, a reference arm, and a detector, said interferometer comprising:
a first polarization dependent splitting element having an input port connected to the optical radiation source, a first output port connected to the sample arm leading to a sample, said first output port transmitting light in a first polarization state towards the sample, and a second output port connected to the reference arm, said second output port transmitting light in a second polarization state different from the first polarization state;
a second polarization dependent splitting element having an input port connected to the sample arm and an output port; and
a substantially non-polarization dependent combiner having a first input port for receiving light that has passed through the sample arm from the output port of the second polarization dependent splitting element, a second input port for receiving light from the reference arm, and an output port for transmitting light received from the sample arm and the reference arm to the detector.

2. The interferometer as recited in claim 1 , in which the first polarization dependent splitting element and the second polarization splitting element are the same.

3. The interferometer as recited in claim 1 , wherein the detector is a dual-balanced detector.

4. The interferometer as recited in claim 1 , wherein said optical radiation source is polarized.

5. The interferometer as recited in claim 1 , further comprising a polarizer between the optical radiation source and the first polarization dependent beamplitting element.

6. The interferometer as recited in claim 1 , wherein power in the reference arm is adjusted by adjusting the polarization state of the source relative to the polarization dependence of the first polarization dependent splitting element.

7. The interferometer as recited in claim 1 , wherein light transmitted through the second polarization dependent beamsplitting element has a polarization state orthogonal to the first polarization state of the light transmitted to the sample arm through the first polarization dependent splitting element.

8. The interferometer as recited in claim 1 , further comprising a polarization manipulating element for manipulating a polarization state of the light transmitted through it, said polarization manipulating element placed between the first or the second polarization dependent splitting element and the sample.

9. The interferometer as recited in claim 1 , further comprising a polarization manipulating element for manipulating a polarization state of the light transmitted through it, said polarization manipulating element placed between the optical radiation source and the first polarization dependent splitting element.

10. The interferometer as recited in claim 1 , wherein the light from the optical radiation source to the sample is transmitted without coupling to a single mode optical fiber.

11. The interferometer as recited in claim 1 , wherein the first and the second polarization dependent elements are combined into a single polarization dependent beamsplitting element having four ports, wherein a first port receives light from the optical radiation source, a second port transmits light in the first polarization state towards the sample, a third port transmits light in the second polarization state to the reference arm, and a fourth port transmits light returned from the sample to the non-polarization dependent combiner.

12. The interferometer as recited in claim 1 , wherein the optical radiation source is a low coherence optical radiation source and the detector is a spectrally sensitive detector, said spectrally sensitive detector being a spectrometer.

13. The interferometer as recited in claim 1 , wherein said light source is a swept source.

14. The interferometer as recited in claim 1 , further comprising a polarization manipulating element in the reference arm.

15. An interferometer for use in an optical coherence tomography (OCT) imaging system, said system having a swept light source, a sample arm leading to a sample to be imaged, a reference arm, and a dual balanced detector, said interferometer comprising:
free space optics for directing light from the swept light source to the sample, said free space optics comprising non-reciprocal beamplitting elements including a polarization dependent beamsplitting element and a polarization manipulator, said polarization dependent beamsplitting element having an input port for receiving light from the swept light source, a first output port for sending light towards the sample, and a second output port for transmitting light returning from the sample, said polarization manipulator configured to manipulate the polarization state of the light transmitted through the manipulator and is located in between the polarization dependent beamsplitting element and the sample; and
a non-polarization dependent combiner having a first input port for receiving light returning from the sample from the polarization dependent beamsplitting element, a second input port for receiving light from the reference arm, and an output port for transmitting light received from the sample and the reference arm to the dual balanced detector.

16. The interferometer as recited in claim 15 , wherein the free space optics further comprise a non-polarizing dielectric beamsplitting element for splitting light from the swept light source into the sample arm and the reference arm, wherein an output port of the non-polarizing dielectric beamsplitting element is connected to the input port of the polarization dependent beamsplitting element.

17. The interferometer as recited in claim 15 , wherein the polarization manipulator is a quarter wave plate.

18. The interferometer as recited in claim 15 , wherein said swept light source has an output power of less than 5 mW.

19. The interferometer as recited in claim 15 , wherein the sample is an eye.

20. An interferometer for use in an optical coherence tomography (OCT) imaging system, said system having an optical radiation source, a sample arm, a reference arm, and a detector, said interferometer comprising:
a polarization dependent splitting element having a first port for receiving light from the optical radiation source, a second port for transmitting light in a first polarization state to the sample arm, a third port for transmitting light in a second polarization state different from the first polarization state to the reference arm, and a fourth port for transmitting light returned from the sample arm; and
a substantially non-polarization dependent combiner having a first input port for receiving light that has passed through the sample arm and exited through the fourth port of the polarization dependent splitting element, said non-polarization dependent combiner having a second input port for receiving light from the reference arm, said non-polarization dependent combiner having an output port for transmitting light received from the sample arm and the reference arm to the detector.

Assignees

• Zeiss Carl Meditec Inc

Inventors

• Tumlinson Alexandre R
• Everett Matthew J

Classifications

• G01B9/02091

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

• G01B9/02051

  Integrated design, e.g. on-chip or monolithic · CPC title

• G01B9/02015 Primary

  characterised by the beam path configuration · CPC title

• A61B3/102

  for optical coherence tomography [OCT] · CPC title

• G01B2290/70

  Using polarization in the interferometer · CPC title