Apparatus and method for ranging and noise reduction of low coherence interferometry LCI and optical coherence tomography OCT signals by parallel detection of spectral bands

• US 7,643,153 B2
• Filed: 12/13/2007
• Issued: 01/05/2010
• Est. Priority Date: 01/24/2003
• Status: Expired due to Term

• Current Assignee: The General Hospital Corporation (Mass General Brigham, Inc.)
• Original Assignee: The General Hospital Corporation (Mass General Brigham, Inc.)
• Inventors: Bouma, Brett Eugene, Tearney, Guillermo J., de Boer, Johannes F.
• Primary Examiner(s): Connolly; Patrick J
• Application Number:
  US11/956,079
• Publication Number:
  US 20080094637A1
• Time in Patent Office: 754 Days
• Field of Search: 356/479, 356/497, 356/456
• US Class Current: 356/497
• 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 5/7257 using Fourier transforms
• CPC Class Codes: G01B 2290/45 Multiple detectors for detecting interferometer signals
• CPC Class Codes: G01B 9/02044 Imaging in the frequency domain, e.g. by using a spectrometer
• CPC Class Codes: G01B 9/02079 Quadrature detection, i.e. detecting relatively phase-shifted signals
• CPC Class Codes: G01B 9/0209 Low-coherence interferometers
• CPC Class Codes: G01B 9/02091 Tomographic interferometers, e.g. based on optical coherence
• CPC Class Codes: G01N 21/4795 spatially resolved investigating of object in scattering medium in vivo A61B

Abstract

Apparatus, method, logic arrangement and storage medium are provided for increasing the sensitivity in the detection of optical coherence tomography and low coherence interferometry (“LCI”) signals by detecting a parallel set of spectral bands, each band being a unique combination of optical frequencies. The LCI broad bandwidth source can be split into N spectral bands. The N spectral bands can be individually detected and processed to provide an increase in the signal-to-noise ratio by a factor of N. Each spectral band may be detected by a separate photo detector and amplified. For each spectral band, the signal can be band pass filtered around the signal band by analog electronics and digitized, or, alternatively, the signal may be digitized and band pass filtered in software. As a consequence, the shot noise contribution to the signal is likely reduced by a factor equal to the number of spectral bands, while the signal amplitude can remain the same. The reduction of the shot noise increases the dynamic range and sensitivity of the system.

Claims

1. An apparatus for optical imaging of at least one portion of a sample, comprising:

a) an interferometer providing at least one signal;

b) a spectral separating unit which splits the at least one signal received from the interferometer into a plurality of optical frequencies; and

c) a plurality of detectors, each detector being configured to detect at least a portion of the optical frequencies received from the spectral separating unit, wherein the sample is scanned in a series of simultaneous illuminations of substantially all of areas of the sample to provide at least one radiation associated with the sample to be used by the interferometer to provide the at least one signal, wherein the interferometer receives at least one electro-magnetic radiation from a transmissive reference, and generates the at least one signal as a function of the at least one electro-magnetic radiation.

2. The apparatus according to claim 1, further comprising an arrangement which configured to at least one of:

i. reconstruct the signal from the detectors by a mathematical manipulation of each plurality of signals obtained from the detectors, or

ii. track a phase of the signal of the interferometer.

3. The apparatus according to claim 1, further comprising at least one arrangement which is configured to reconstruct the at least one signal from the detectors by a mathematical manipulation.

4. The apparatus according to claim 1, further comprising at least one arrangement which is configured to track the phase of the signal of the interferometer.

5. The apparatus according to claim 1, wherein the spectral separating unit comprises at least one of (i) an addressable mirror array or (ii) a waveguide filter.

6. The apparatus according to claim 1, wherein the spectral separating unit splits the signal into the bands.

7. The apparatus according to claim 1, wherein the detectors are provided in a form of a two-dimensional array.

8. The apparatus according to claim 1, wherein the spectral separating unit comprises a polarization separating unit.

9. The apparatus according to claim 1, wherein the spectral separating unit at least one of:

i. comprises at least one of (i) an addressable mirror array or (ii) a waveguide filter, or

ii. splits the signal into a plurality of bands, whereby at least one of the bands comprises spectra that has a comb-like structure.

10. The apparatus according to claim 1, wherein the interferometer comprises an arrangement generating a path length difference that is a fraction of a ranging depth of the interferometer.

11. An apparatus, comprising:

a) a spectral separating arrangement configured to receive a plurality of electro-magnetic signals from an interferometer, and to separate the electromagnetic signals into a plurality of spectral bands, the electromagnetic signals being associated with characteristics of at least one of a plurality of portions of a sample, wherein at least two of the portions of the sample are irradiated simultaneously; and

b) a detecting arrangement configured to detect at least one of the spectral bands received from the spectral separating arrangement, and configured to generate at least one resultant signal for use to image the at least one of the at least two of the portions of the sample, wherein the spectral separating arrangement receives at least one electro-magnetic radiation from a transmissive reference, and generates the spectral bands as a function of the at least one electromagnetic radiation.

12. A logic arrangement to provide data, which, when executed by a processing arrangement, configures the processing arrangement to execute the steps comprising of:

a) receiving signals that correspond to spectral bands of more than one electro-magnetic signals from a detecting arrangement, the detecting arrangement detecting the spectral bands that are separated from the electromagnetic signals by a spectral separating arrangement, the spectral separating arrangement receiving the electro-magnetic signals from an interferometer, the electromagnetic signals being associated with characteristics of at least one of a plurality of portions of a sample, wherein at least two of the portions of the sample are irradiated simultaneously, wherein the spectral bands are generated as a function of the at least one electromagnetic radiation associated with at least one electromagnetic radiation received from a transmissive reference; and

b) generating the data based on information corresponding to the received signals.

13. A method for providing data, comprising the steps of:

a) receiving signals that correspond to spectral bands of the at least one electro-magnetic signal from a detecting arrangement, the detecting arrangement detecting the spectral bands that are separated from the at least one electromagnetic signal by a spectral separating arrangement, the spectral separating arrangement receiving the electromagnetic signals from an interferometer, the electromagnetic signals being associated with characteristics of at least one of a plurality of portions of a sample, wherein at least two of the portions of the sample are irradiated simultaneously, wherein the spectral bands are generated as a function of the at least one electromagnetic radiation associated with at least one electromagnetic radiation received from a transmissive reference; and

b) generating the data based on information corresponding to the received signals.

14. A storage medium including executable instructions thereon to provide data, wherein, when the executable instructions are executed by a processing system, the executable instructions configure the processing system to perform the steps comprising of:

a) receiving signals that correspond to spectral bands of a plurality of electro-magnetic signal from a detecting arrangement, the detecting arrangement detecting the spectral bands that are separated from the electromagnetic signals by a spectral separating arrangement, the spectral separating arrangement receiving the electro-magnetic signals from an interferometer, the electromagnetic signals being associated with characteristics of at least one of a plurality of portions of a sample, wherein at least two of the portions of the sample are irradiated simultaneously, wherein the spectral bands are generated as a function of the at least one electromagnetic radiation associated with at least one electromagnetic radiation received from a transmissive reference; and

b) generating the data based on information corresponding to the received signals.

15. An apparatus for optical imaging of at least one portion of a sample, comprising:

a) an interferometer providing at least one signal;

b) a spectral separating unit which splits the at least one signal received from the interferometer into a plurality of optical frequencies;

c) a plurality of detectors, each detector being configured to detect at least a portion of the optical frequencies received from the spectral separating unit, wherein the sample is scanned in a series of simultaneous illuminations of substantially all of areas of the sample to provide at least one radiation associated with the sample to be used by the interferometer to provide the at least one signal; and

d) an arrangement configured to track the phase of the signal of the interferometer.