Speckle reduction in optical coherence tomography by path length encoded angular compounding

• US 7,567,349 B2
• Filed: 03/31/2004
• Issued: 07/28/2009
• Est. Priority Date: 03/31/2003
• Status: Active Grant

• Current Assignee: The General Hospital Corporation (Mass General Brigham, Inc.)
• Original Assignee: The General Hospital Corporation (Mass General Brigham, Inc.)
• Inventors: Iftimia, Nicusor, Bouma, Brett Eugene, Tearney, Guillermo J.
• Primary Examiner(s): Turner; Samuel A
• Application Number:
  US10/551,735
• Publication Number:
  US 20060227333A1
• Time in Patent Office: 1,945 Days
• Field of Search: 356/477, 356/479, 356/497
• US Class Current: 356/479
• CPC Class Codes: A61B 5/0059 using light, e.g. diagnosis by transillumination, diascopy, fluorescence A61B5/0093, A61B5/1455, A61B5/02416 and A61B5/0261 take precedence
• CPC Class Codes: A61B 5/0066 Optical coherence imaging
• CPC Class Codes: A61B 5/6852 Catheters
• CPC Class Codes: G01B 9/02028 Two or more reference or object arms in one interferometer
• CPC Class Codes: G01B 9/02082 Caused by speckles
• CPC Class Codes: G01B 9/02087 Combining two or more images of the same region
• CPC Class Codes: G01B 9/02091 Tomographic interferometers, e.g. based on optical coherence
• CPC Class Codes: G01J 9/0215 by shearing interferometric methods
• CPC Class Codes: G01N 21/4795 spatially resolved investigating of object in scattering medium in vivo A61B
• CPC Class Codes: G02B 26/105 with one or more pivoting mirrors or galvano-mirrors G02B26/101 takes precedence
• CPC Class Codes: G02B 27/48 Laser speckle optics

Abstract

Speckle, a factor reducing image quality in optical coherence tomography (“OCT”), can limit the ability to identify cellular structures that are important for the diagnosis of a variety of diseases. Exemplary embodiments of the present invention can facilitate an implementation of an angular compounding, angular compounding by path length encoding (“ACPE”) for reducing speckle in OCT images. By averaging images obtained at different incident angles, with each image encoded by path length, ACPE maintains high-speed image acquisition and implements minimal modifications to OCT probe optics. ACPE images obtained from tissue phantoms and human skin in vivo demonstrate a qualitative improvement over traditional OCT and an increased signal-to-noise ratio (“SNR”). Accordingly, exemplary embodiments of an apparatus probe catheter and method can be provided for irradiating a sample. In particular, an interferometer may forward forwarding an electromagnetic radiation. In addition, a sample arm may receive the electromagnetic radiation, and can include an arrangement which facilitates a production of at least two radiations from the electromagnetic radiation so as to irradiate the sample. Such exemplary arrangement can be configured to delay a first radiation of the at least two radiations with respect to a second radiation of the at least two radiations.

Claims

1. An apparatus for irradiating a sample, comprising:

a) an interferometer forwarding an electromagnetic radiation;

b) a sample arm receiving the electromagnetic radiation, the sample arm including an arrangement which is configured to produce at least two radiations from the electromagnetic radiation so as to irradiate the sample, and to delay a first radiation of the at least two radiations with respect to a second radiation of the at least two radiations;

c) a reference arm providing a further electromagnetic radiation, wherein the interferometer receives the first, second and further radiations, and forms a resultant signal based on the first, second and further radiations; and

d) a processing arrangement generating a first image based on the first radiation, a second image based on the resultant signal and a further image based on the first and second images,

wherein the first and second images are different from one another, and

wherein the further image has a signal to noise ratio that is improved according to the equation;

2. The apparatus according to claim 1, wherein the further image has a noise that is smaller than a noise of the first image and a noise of the second image.

3. The apparatus according to claim 1, wherein m=2 and N=3 images associated with the at least two radiations are obtained.

4. The apparatus according claim 1, wherein the further image is generated based on a mathematical combination of the first and second images.

5. The apparatus according to claim 1, wherein the arrangement irradiates the sample by the first irradiation at a first angle, and by the second radiation at a second angle, the first and second angles being different from one another.

6. The apparatus according to claim 5, wherein the first and second angle are different from one another as a function of the delay and at least one of a phase or a incident angle of each of the first and second radiations.

7. The apparatus according to claim 1, further comprising a detector which detects the first electromagnetic radiation, and forwards the detected energy to the processing arrangement.

8. The apparatus according to claim 1, wherein the arrangement includes two sections, each being configured to delay a respective one of the first and second radiations, and wherein a delay of the first radiation is greater than a delay of the second radiation.

9. An apparatus for irradiating a sample, comprising:

a) an interferometer forwarding an electromagnetic radiation; and

b) a sample arm receiving the electromagnetic radiation, the sample arm including an arrangement which is configured to produce at least two radiations from the electromagnetic radiation so as to irradiate the sample, and to delay a first radiation of the at least two radiations with respect to a second radiation of the at least two radiations, wherein the delay of a path of the first radiation compared to a path of the second radiation is at least 500 μ

m in air.

10. The apparatus according to claim 9, wherein the delay of the path of the first radiation compared to the path of the second radiation is at least about 1 mm in air.

11. An apparatus for irradiating a sample, comprising:

a) an interferometer forwarding an electromagnetic radiation; and

b) a sample arm receiving the electromagnetic radiation, the sample arm including an arrangement which is configured to produce at least two radiations from the electromagnetic radiation so as to irradiate the sample, and to delay a first radiation of the at least two radiations with respect to a second radiation of the at least two radiations, wherein the arrangement has at least one of;

first optical section with a refractive index of at least 1.5, the first section being structured to propagate the at least two radiations,

a second section which has silicon, the second section being structured to propagate the at least two radiations.

12. The apparatus according to claim 11, wherein the refractive index of the optical section is at least 3.0.

13. The apparatus according to claim 11, wherein at least one of the first section or the second section comprises an anti-reflection-coated BK 7 glass.

14. The apparatus according to claim 13, wherein the glass has a thickness of from about 1.6 mm to about 7.7 mm.

15. The apparatus according to claim 11, wherein at least one of the first section or the second section comprises an anti-reflection-coated glass that has a refractive index of from about 1.51 to about 3.5.

16. A method for irradiating a sample, comprising:

a. providing an electromagnetic radiation from an interferometer;

b. in a sample arm, producing at least two radiations from the electromagnetic radiation so as to irradiate the sample, a first radiation of the at least two radiations being delayed with respect to a second radiation of the at least two radiations;

c. providing a further electromagnetic radiation, wherein the interferometer receives the first, second and further radiations and forms a resultant signal based on the first, second and further radiations; and

d. generating a first image based on the first radiation, a second image based on the resultant signal and a further image based on the first and second images,

wherein the first and second images are different from one another, and

wherein the further image has a signal to noise ratio that is improved according to the equation;

17. An apparatus for imaging, comprising:

a. a sample arm receiving an electromagnetic radiation, the sample arm including an arrangement which is configured to produce at least two radiations from the electromagnetic radiation so as to irradiate a sample, and to delay a first radiation of the at least two radiations with respect to a second radiation of the at least two radiations;

b. a device receiving the first and second radiations from the sample arm and at least one third radiation from a reference arm, wherein the first and second radiations interfere with the third radiation;

c. at least one spectral separating arrangement which cooperates with the sample arm, and separates spectrum of at least one of the first, second and third radiations into frequency components; and

d. at least one detection arrangement including a plurality of detectors, each detector capable of detecting at least a portion of at least one of the frequency components;

e. a reference arm providing a further electromagnetic radiation, wherein the interferometer receives the first, second and further radiations, and forms a resultant signal based on the first, second and further radiations; and

f. a processing arrangement generating a first image based on the first radiation, a second image based on the resultant signal and a further image based on the first and second images,

wherein the first and second images are different from one another, and

wherein the further image has a signal to noise ratio that is improved according to the equation;

18. An apparatus for obtaining information associated with a sample, comprising;

a first arrangement configured to separating at least one first electro-magnetic radiation into a first radiation and a second radiation forwarded to a sample, wherein the first and second radiations having different path lengths;

a second arrangement configured to received third and fourth radiations from the sample associated with the first and second radiations and a fifth radiation received from a reference, and generate at least one interference signal as a function of the third, fourth and fifth radiations;

a third arrangement configured to generate;

first data associated with the third radiation which includes a first speckle pattern and second data associated with the fourth radiation which includes a second speckle pattern, and

third data associated with the sample based on the first and second data that has a speckle pattern the amount of which is smaller that the amount of at least one of the first speckle pattern or the first speckle pattern.

19. The apparatus according to claim 18, wherein the first, second and third data are images.

20. The apparatus according to claim 18, wherein the first arrangement includes an optical section with a refractive index of at least 1.5, the optical section being structured to propagate the first and second radiations.

21. The apparatus according to claim 18, wherein the first arrangement includes a section which has silicon that Is structured to propagate the first and second radiations.

22. The apparatus according to claim 18, wherein the first arrangement includes a section which has an anti-reflective coating on at least one surface thereof, the section being structured to propagate the first and second radiations.

28. The apparatus according to claim 18, wherein the first, second and the third data are images, the third image data having a noise that is smaller than a noise of the first image data and a noise of the second image data.

29. The apparatus according claim 18, wherein the first, second and the third data are images, and wherein the third arrangement is configured to generate the third image data based on a mathematical combination of the first and second image data.

30. The apparatus according to claim 18, further comprising an arrangement which is configured to irradiate the sample by the first irradiation at a first angle, and by the second radiation at a second angle, the first and second angles being different from one another.

31. The apparatus according to claim 30, wherein the first and second angle are different from one another as a function of a delay between the first and second radiations and at least one of a phase or a incident angle of each of the first and second radiations.

32. The apparatus according to claim 18, further comprising a detector which detects the first radiation, and forwards the detected energy to the third arrangement.

33. The apparatus according to claim 18, further comprising an arrangement which includes two sections, each being configured to delay a respective one of the first and second radiations, and wherein a delay of the first radiation is greater than a delay of the second radiation.

23. An apparatus for obtaining information associated with a sample, comprising;

a first arrangement configured to separating at least one first electro-magnetic radiation into a first radiation and a second radiation forwarded to a sample, wherein the first and second radiations having different path lengths;

a second arrangement configured to received third and fourth radiations from the sample associated with the first and second radiations and a fifth radiation received from a reference, and generate at least one interference information as a function of the third, fourth and fifth radiations; and

a third arrangement configured to generate data corresponding to an amount of a ranging depth within the sample associated with the second arrangement, wherein a difference between the path lengths of the first and second radiations is equal or greater than the ranging depth.

24. The apparatus according to claim 23, wherein the first arrangement includes an optical section with a refractive index of at least 1.5, the optical section being structured to propagate the first and second radiations.

25. The apparatus according to claim 23, wherein the first arrangement includes a section which has silicon that Is structured to propagate the first and second radiations.

26. The apparatus according to claim 23, wherein the first arrangement includes a section which has an anti-reflective coating on at least one surface thereof, the section being structured to propagate the first and second radiations.

27. The apparatus according to claim 23, wherein the ranging depth is a penetration depth in the sample, the sample including an anatomical structure.