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 20080094613A1
• Filed: 12/13/2007
• Published: 04/24/2008
• Est. Priority Date: 01/24/2003
• Status: Active Grant

• Current Assignee: The General Hospital Corporation (Mass General Brigham, Inc.)
• Original Assignee: The General Hospital Corporation (Mass General Brigham, Inc.)
• Inventors: Tearney, Guillermo, de Boer, Johannes, Bouma, Brett
• Granted Patent: US 8,054,468 B2
• Time in Patent Office: Days
• US Class Current: 356/73
• 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 and method 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 is split into N spectral bands. The N spectral bands are individually detected and processed to provide an increase in the signal-to-noise ratio by a factor of N. Each spectral band is detected by a separate photo detector and amplified. For each spectral band the signal is 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 reduced by a factor equal to the number of spectral bands. The signal remains the same. The reduction of the shot noise increases the dynamic range and sensitivity of the system.

Claims

1-102. -102. (canceled)

103. An apparatus for optical imaging, comprising:

a) an interferometer;

b) an arrangement generating a path length difference that is a fraction of a ranging depth of the interferometer;

c) a spectral separating unit which splits signal received from the interferometer into a plurality of optical frequencies which utilizes a signal received from the arrangement; and

d) a plurality of detectors, each detector capable of detecting at least a portion of the optical frequencies received from the spectral separating unit.

104. The apparatus according to claim 103, wherein the arrangement comprises a fiber stretching arrangement.

105. The apparatus according to claim 103, wherein the arrangement comprises a piezoelectric transducer configured to perform free space translational scanning.

106. The apparatus according to claim 103, wherein the arrangement comprises a phase control optical delay line.

107. The apparatus according to claim 103, wherein the arrangement scans over at least a fraction of the ranging depth equal to one over the number of detectors.

108. The apparatus according to claim 103, wherein the arrangement further comprises a carrier frequency generator.

109. The apparatus according to claim 103, wherein the arrangement comprises an acoustic modulator.

110. The apparatus according to claim 103, wherein the arrangement comprises an electro-optic modulator.

111. The apparatus according to claim 103, wherein the arrangement comprises a phase control RSOD.

112. The apparatus according to claim 103, wherein the arrangement produces a delay that has a distance that is less than a range of a sample arm.

113. The apparatus according to claim 103, wherein the spectral separating unit comprises the at least one of (i) the addressable mirror array, (ii) the linear array of optical filters, (iii) the waveguide filter, or (iv) the waveguide gratings.

114. The apparatus according to claim 103, wherein the spectral separating unit splits the signal into the bands.

115. The apparatus according to claim 103, wherein the detectors are provided in a form of a two-dimensional array.

116. The apparatus according to claim 103, wherein the sample is scanned in a series of simultaneous illuminations of substantially all of the area of the sample.

117. The apparatus according to claim 103, further comprising the polarization separating unit.

118. The apparatus according to claim 103, wherein the spectral separating unit at least one of:

i. comprises at least one of (i) an addressable mirror array, (ii) a linear array of optical filters, (iii) a waveguide filter, or (iv) waveguide gratings, 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.

119. The apparatus according to claim 103, wherein the sample is scanned in a series of simultaneous illuminations of substantially all of the area of the sample.

120. The apparatus according to claim 103, further comprising an arrangement generating a path length difference that is a fraction of a ranging depth of the interferometer.