Optical coherence tomography (OCT) system with improved image quality

Patent metadata

Field	Value
Publication number	US-10856735-B2
Application number	US-201716465070-A
Country	US
Kind code	B2
Filing date	Nov 27, 2017
Priority date	Nov 30, 2016
Publication date	Dec 8, 2020
Grant date	Dec 8, 2020

Abstract

This disclosure relates to the field of Optical Coherence Tomography (OCT). This disclosure particularly relates to an OCT system that generates an image with improved quality. In one example, the OCT system may generate an improved Bscan image by using multiple shaping functions to shape the raw A-scans. In another example, the OCT system may generate the improved B-scan image by forming multiple apodization patterns on a detector and acquiring raw A-scans by using the apodization patterns. A better diagnosis of a health condition may be reached by using the improved images generated by the OCT system of this disclosure.

First claim

The invention claimed is:

1. An optical coherence tomography (OCT) system for generating a B-scan image of a target that has a surface and a depth, comprising:
an optical system; and
an image generation system;
wherein:
the optical system comprises an illumination source, a beam splitter, a target arm, a reference arm, and an optical detection system;
the image generation system comprises a control unit, a processing unit, a memory unit, and a display unit; and
the OCT system has a configuration that, during operation:
illuminates and scans the target;
forms discretized OCT interference spectra;
generates at least two raw A-scans;
shapes each raw A-scan by using at least two different shaping functions for each raw A-scan to form at least two shaped A-scans for each raw A-scan;
forms at least two B-scans (“shaped B-scans”), wherein the shaped A-scans forming the same shaped B-scan are shaped with the same shaping function;
determines a maximum intensity of each shaped B-scan;
normalizes each shaped B-scan (“normalized B-scan”) by using the maximum intensity of the same shaped B-scan;
forms sets of pixels, wherein each pixel set comprises one pixel (“B-scan pixel”) from each normalized B-scan, wherein the B-scan pixels of each pixel set have the same position on all normalized B-scans;
determines one intensity (“optimized intensity”) for each pixel set by applying a mathematical operation to intensities of pixels forming the same pixel set; wherein the mathematical operation comprises a rank order filter, a mean filter, a multi-image deconvolution, or a combination thereof;
generates a new B-scan (“new B-scan”) based on the optimized intensities of the pixel sets; and
displays the new B-scan on the image generation system's display unit.

2. The OCT system of claim 1 , wherein the shaping function comprises a function that is zero-valued outside of a chosen interval.

3. The OCT system of claim 1 , wherein the shaping function comprises a window function, a Gaussian function, or a combination thereof.

4. The OCT system of claim 1 , wherein the mathematical operation comprises a rank order filter that is a minimum filter, a median filter, a rank order filter that has a rank between that of the minimum filter and the median filter, or a combination thereof.

5. The OCT system of claim 1 , wherein the mathematical operation comprises a mean filter that is an arithmetic mean, a weighted mean, a geometric mean, a harmonic mean, a quadratic mean, a logarithmic mean, or a combination thereof.

6. The OCT system of claim 1 , wherein the OCT system has a configuration that, during operation, smooths the new B-scan by using a digital smoothing filter.

7. The OCT system of claim 1 , wherein the OCT system has a configuration that, during operation, smooths the new B-scan by using a digital smoothing filter; and wherein the digital smoothing filter comprises a linear smoothing filter, a non-linear smoothing filter, or a combination thereof.

8. The OCT system of claim 1 , wherein the OCT system has a configuration that, during operation, smooths the generated new B-scan by using a digital smoothing filter; and
wherein the digital smoothing filter comprises a median filter, a Gaussian filter, or a combination thereof.

9. The OCT system of claim 1 , wherein the optical detection system comprises a spectrometer, wherein the spectrometer comprises a detector, and wherein the detector comprises at least three pixels (“detector pixels”).

10. The OCT system of claim 9 , wherein the the spectrometer further comprises an optical grating, a first optical lens between the beam splitter and the grating, and a second optical lens between the optical grating and the detector; and wherein the first lens, the grating and the second lens have a configuration that projects an interfered light beam formed by the beam splitter on the at least three pixels.

11. The OCT system of claim 9 , wherein the OCT system has a configuration that, during operation:
illuminates and scans at least one physical position on the target surface;
forms sets of detector pixels, wherein each detector pixel set comprises at least two detector pixels, and wherein the detector pixels forming the same detector pixel set are adjacent to each other;
forms discretized OCT interference spectra on each detector pixel;
generates at least two A-scans, wherein each A-scan is generated from the discretized OCT interference spectra formed on each detector pixel;
forms at least two B-scans (“shaped B-scans”) based on the generated A-scans, wherein the A-scans forming each shaped B-scan are generated from the discretized OCT interference spectra formed on the detector pixels of the same detector pixel set;
determines a maximum intensity of each shaped B-scan;
normalizes each shaped B-scan (“normalized B-scan”) by using the maximum intensity of the same shaped B-scan;
forms sets of pixels, wherein each pixel set comprises one pixel (“B-scan pixel”) from each normalized B-scan, and wherein the B-scan pixels of each pixel set have the same position on all normalized B-scans;
determines one intensity (“optimized intensity”) for each pixel set by applying a mathematical operation to intensities of pixels forming the same pixel set; wherein the mathematical operation comprises a rank order filter, a mean filter, a multi-image deconvolution, or a combination thereof;
generates a new B-scan (“new B-scan”) based on the optimized intensities of the pixel sets; and
displays the new B-scan on the image generation system's display unit.

12. The OCT system of claim 11 , wherein the mathematical operation comprises a rank order filter that is a minimum filter, a median filter, a rank order filter that has a rank between that of the minimum filter and the median filter, or a combination thereof.

13. The OCT system of claim 11 , wherein the mathematical operation comprises a mean filter that is an arithmetic mean, a weighted mean, a geometric mean, a harmonic mean, a quadratic mean, a logarithmic mean, or a combination thereof.

14. The OCT system of claim 11 , wherein the OCT system has a configuration that smooths the generated new B-scan by using a digital smoothing filter.

15. The OCT system of claim 11 , wherein the OCT system has a configuration that smooths the generated new B-scan by using a digital smoothing filter; and wherein the digital smoothing filter comprises a linear smoothing filter, a non-linear smoothing filter, or a combination thereof.

16. The OCT system of claim 11 , wherein the OCT system has a configuration that smooths the generated new B-scan; and wherein the digital smoothing filter comprises a median filter, a Gaussian filter, or a combination thereof.

Assignees

• Univ Southern California

Inventors

• Chen Yu
• Fraser Scott E

Classifications

• G06T2207/30041

  Eye; Retina; Ophthalmic · CPC title

• A61B3/102 Primary

  for optical coherence tomography [OCT] · CPC title

• A61B3/152

  for aligning · CPC title

• A61B3/14

  Arrangements specially adapted for eye photography · CPC title

• A61B5/0066

  Optical coherence imaging · CPC title