Search Images Maps Play YouTube News Gmail Drive More »
Sign in
Screen reader users: click this link for accessible mode. Accessible mode has the same essential features but works better with your reader.

Patents

  1. Advanced Patent Search
Publication numberUSRE42497 E1
Publication typeGrant
Application numberUS 12/205,248
Publication dateJun 28, 2011
Filing dateSep 5, 2008
Priority dateMay 6, 2003
Fee statusPaid
Also published asUS7102758, US20040223162, WO2004102109A2, WO2004102109A3
Publication number12205248, 205248, US RE42497 E1, US RE42497E1, US-E1-RE42497, USRE42497 E1, USRE42497E1
InventorsAdam Wax
Original AssigneeDuke University
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Fourier domain low-coherence interferometry for light scattering spectroscopy apparatus and method
US RE42497 E1
Abstract
An apparatus and method for obtaining depth-resolved spectra for the purpose of determining the size of scatterers by measuring their elastic scattering properties. Depth resolution is achieved by using a white light source in a Michelson interferometer and dispersing a mixed signal and reference fields. The measured spectrum is Fourier transformed to obtain an axial spatial cross-correlation between the signal and reference fields with near 1 μm depth-resolution. The spectral dependence of scattering by the sample is determined by windowing the spectrum to measure the scattering amplitude as a function of wavenumber.
Images(10)
Previous page
Next page
Claims(64)
1. A method of obtaining depth-resolved spectra of a sample for determining size and depth characteristics of scatterers within the sample, comprising the steps of:
emitting a beam onto a splitter, wherein the splitter is fixed with respect to the sample, and wherein the splitter splits light from the beanbeam to produce a reference beam, which is reflected to produce a reflected reference beam, and an input beam to the sample comprised of a substrate having a first surface and a second surface;
cross-correlating the reflected reference beam with a reflected sample beam scattered from the sample as a result of the input beam by mixing the reflected reference beam and the reflectedscattered sample beam;
spectrally dispersing the mixed reflected reference beam and the reflectedscattered sample beam to yield a single spectrally resolved,spectrally-resolved cross-correlated reflection profile having depth-resolved information about the reflectedscattered sample beam; and
generating a spectroscopic depth-resolved reflection profile, by processingthat includes characteristics of scatterers within the sample by:
providing one or more spectral windows of the single spectrally-resolved cross-correlated reflection profile by: at a plurality of different center wavelengths, applying a window to the single spectrally-resolved cross-correlated reflection profile at, each of the one or more spectral windows having a given center wavelength to obtain spectral information at the given center wavelengthabout the sample for each of the one or more spectral windows; and
converting the windowedapplying a Fourier transform to the spectral information via a Fourier transform to recover depth-resolved information about the sample at alleach given center wavelengthswavelength simultaneously.
2. The method of claim 1, further comprising recovering size information about the scatterers from the spectroscopic depth-resolved reflection profile.
3. The method of claim 2, wherein recovering the size information is obtained by measuring a frequency of a spectral modulation in the spectroscopic depth-resolved reflection profile.
4. The method of claim 2, wherein recovering the size information is obtained by comparing the spectroscopic depth-resolved reflection profile to a predicted analytical or numerical scattering distribution of the sample.
5. The method of claim 1, wherein applying a processing algorithmproviding one or more spectral windows is comprised of applying aproviding one or more Gaussian windowwindows, one or more multiple simultaneous windows, or one or more other window.
6. The method of claim 1, wherein the splitter is comprised from the group consisting of a beam splitter and an optical fiber splitter.
7. The method of claim 1, wherein emitting a beam onto the splitter comprises emitting a collimated beam.
8. The method of claim 7, wherein the input beam comprises a collimated beam.
9. The method of claim 7, wherein the reflected reference beam comprises a collimated beam.
10. The method of claim 1, wherein the beam is comprised of a light comprised of white light from an arc lamp or thermal source.
11. The method of claim 1, wherein cross-correlating the reflected reference beam with the reflectedscattered sample beam comprises determining an interference term by measuring the intensity of the reflectedscattered sample beam and the reflected reference beam independently and subtracting them from the total intensity of the reflectedscattered sample beam.
12. The method of claim 1, wherein the reflected reference beam is created by reflecting the reference beamreflected off of a reference mirror.
13. The method of claim 1, wherein the length of the path of the reference beam is fixed.
14. The method of claim 1, wherein the splitter is attached to a fixed reference arm.
15. The method of claim 1, wherein the sample is attached to a fixed sample arm.
16. The method of claim 1, wherein dispersing the mixed reflected reference beam and reflectedscattered sample beam is performed using a spectrograph.
17. A method of obtaining depth-resolved spectra of a sample comprised of a substrate having a first surface and a second surface for determining size and depth characteristics of scatterers within the sample, comprising the steps of:
emitting a beam onto a splitter wherein the splitter is fixed with respect to the sample, wherein the splitter splits light from the beam to produce a reference beam, which is reflected to produce a reflected reference beam, and an input beam to the sample comprised of a substrate having a first surface and a second surface;
cross-correlating the reflected reference beam with a first reflectedscattered sample beam comprised of a first portion of light scattered from the first surface, by mixing the reflected reference beam and the first portion of light;
cross-correlating the reflected reference beam with a second reflectedscattered sample beam comprised of a second portion of light scattered from the second surface, by mixing the reflected reference beam and the second portion of light;
spectrally dispersing the mixed reflected reference beam and the first reflectedscattered sample beam to yield a first single first spectrally dispersed,spectrally-resolved cross-correlated reflection profile having depth-resolved information about the first surface of the substrate;
spectrally dispersing the mixed reflected reference beam and the second reflectedscattered sample beam to yield a second single second spectrally dispersed,spectrally-resolved cross-correlated reflection profile having depth-resolved information about the second surface of the substrate;
generating a first spectroscopic depth-resolved reflection profile by processing the single spectrally dispersed, first cross-correlated reflection profile by:that includes characteristics of scatterers within the sample by:
at a pluralityproviding one or more first spectral windows of different center wavelengths, applying a window to the first single first spectrally dispersed,spectrally-resolved cross-correlated reflection profile, each of the one or more first spectral windows at a given center wavelength to obtain spectral information at the given center wavelength; and
converting the windowed spectral information via a Fourier transform to recover depth-resolvedfirst spectral information about the first surface of the substrate at all center wavelengths simultaneouslyfor each of the one or more first spectral windows; and
applying a Fourier transform to the first spectral information to recover depth information about the first surface at each given center wavelength simultaneously; andgenerating a second spectroscopic depth-resolved reflection profile by processing the singlethat includes characteristics of scatterers within the sample by:
providing one or more second spectrally dispersed, cross-correlated reflection profile by: at a plurality of different center wavelengths, applying a window to the singlespectral windows of the first spectrally dispersed,single spectrally-resolved cross-correlated reflection profile, each of the one or more second spectral windows at a given center wavelength to obtain spectral information at the given center wavelength; and
converting the windowed spectral information via a Fourier transform to recover depth-resolvedsecond spectral information about the second surface of the substrate at all center wavelength simultaneouslyfor each of the one or more second spectral windows; and
applying a Fourier transform to the second spectral information to recover depth information about the second surface at each given center wavelength simultaneously.
18. The method of claim 17, wherein recovering size information about the sample is comprised of determining a ratio of the first spectroscopic depth-resolved reflection profile and the second spectroscopic depth-resolved reflection profile.
19. The method of claim 17, wherein the first surface is the front of the substrate and the second surface is the back of the substrate or a sample attached to or near the back of the substrate.
20. An apparatus for obtaining depth-resolved spectra of a sample in order to determine the size and depth characteristics of scatterers within the sample, comprising:
a sample that receives a sample beam and reflects a reflected sample beam in response, wherein the reflected sample beam contains light scattered from the sample;
a receiver that is fixed with respectadapted to the sample, that receivesreceive a reflected reference beam and the reflecteda scattered sample beam and cross-correlatescontaining light scattered from a sample in response to the sample receiving a sample beam, wherein the receiver is further adapted to cross-correlate the reflected reference beam with the reflectedscattered sample beam;
a detector thatadapted to spectrally dispersesdisperse the cross-correlated reflected reference beam and reflectedscattered sample beam to yield a single spectrally dispersed,spectrally-resolved cross-correlated reflection profile having depth-resolved information about the reflectedscattered sample beam; and
a processor unit adapted to: generate a spectroscopic depth-resolved reflection profile, by processing the single spectrally-resolved cross-correlated reflection profile by: at a pluralitythat includes characteristics of different center wavelengths, applying a window toscatterers within the sample by:
providing one or more spectral windows of the single spectrally-resolved cross-correlated reflection profile, each of the one or more spectral windows at a given center wavelength to obtain spectral information at the given center wavelengthabout the sample for each of the one or more spectral windows; and
convertingapplying a Fourier transform to the spectral information via Fourier transform to recover depth-resolved spectraldepth information about the sample at alleach given center wavelengthswavelength simultaneously.
21. The apparatus of claim 20, wherein the processor unit is further adapted to recover size information about the sample from the spectroscopic depth-resolved reflection profile.
22. The apparatus of claim 20, wherein the processor unit is further adapted to recover the size information by measuring a frequency of a spectral modulation in the spectroscopic depth-resolved reflection profile.
23. The apparatus of claim 20, wherein the processor unit is further adapted to recover the size information by comparing the spectroscopic depth-resolved reflection profile to a predicted analytical or numerical scattering distribution of the samplemeasuring a frequency of a spectral modulation in the spectroscopic depth-resolved reflection profile.
24. The apparatus of claim 20, wherein applying a processing algorithmproviding one or more spectral windows is comprised of applying aproviding one or more Gaussian windowwindows, one or more multiple simultaneous windows, or one or more other window.
25. The apparatus of claim 20, wherein the receiver is comprised of a splitter.
26. The apparatus of claim 25, wherein the splitter is comprised from the group consisting of a beam splitter and an optical fiber splitter.
27. The apparatus of claim 20, wherein the sample beam comprises a collimated beam.
28. The apparatus of claim 20, wherein the reflected reference beam comprises a collimated beam.
29. The apparatus of claim 20, wherein the received beam is comprised of a light comprised from the group consisting of a white light generated by an arc lamp or thermal source.
30. The apparatus of claim 20, wherein the length of the path of the reference beam is fixed.
31. The apparatus of claim 20, wherein the receiver is attached to a fixed reference arm.
32. The apparatus of claim 20, wherein the sample is attached to a fixed sample arm.
33. The apparatus of claim 20, wherein the detector is comprised of a dispersive element.
34. The apparatus of claim 33, wherein the dispersive element is a spectrograph.
35. An apparatus for obtaining depth-resolved spectra of a sample comprised of a substrate having a first surface and a second surface in order to determine the size and depth characteristics of scatterers within the sample, comprising:
a sample that receives a sample beam and reflects a first and second reflected sample beam in response, wherein the first reflected sample beam is comprised of a first portion of light scattered from the first surface of the sample, and where the second reflected sample beam is comprised of a second portion of light scattered from the second surface of the sample;
a receiver that is fixed with respect to the sample, that receivesadapted to receive a reflected reference beam and the, a first scattered sample beam containing light scattered from a first surface in response to the first surface receiving a sample beam, and a second reflectedscattered sample beamsbeam containing light scattered from a second surface in response to the first surface receiving a sample beam, and cross-correlatescross-correlate the reflected reference beam with the first reflectedscattered sample beam, and the reflected reference beam with the second reflectedscattered sample beam;
a detector thatadapted to spectrally dispersesdisperse the cross-correlated reflected reference beam and the first reflectedscattered sample beam to yield a first single first spectrally dispersed,spectrally-resolved cross-correlated reflection profile having depth-resolved information about the first surface, and spectrally dispersesdisperse the cross-correlated reflected reference beam and the second reflectedscattered sample beam to yield a second single second spectrally dispersed,spectrally-resolved cross-correlated reflection profile having depth-resolved information about the second surface; and
a processor unit adapted to:
generate a first spectroscopic depth-resolved reflection profile, by processing the single first cross-correlated reflection profile by, at a plurality of different center wavelengths:that includes characteristics of scatterers within the sample by:
applying a window to theproviding one or more first spectral windows of the first single firstspectrally-resolved cross-correlated reflection profile, each of the one or more first spectral windows at a given center wavelength to obtain spectral information at the given center wavelength; and
converting the spectral information via Fourier transform to recover depth-resolvedfirst spectral information about the first surface of the sample at all center wavelengths simultaneouslysubstrate for each of the one or more first spectral windows; and
applying a Fourier transform to the first spectral information to recover depth information about the first surface at each given center wavelength simultaneously; and
generate a second spectroscopic depth-resolved reflection profile,that includes characteristics of scatterers within the sample as a function wavelength and depth by processing the single:
providing one or more second cross-correlated reflection profile by:
at a plurality of different center wavelengths, applying a window to the singlespectral windows of the second single spectrally-resolved cross-correlated reflection profile, each of the one or more second spectral windows at a given center wavelength to obtain second spectral information at the given center wavelengthabout the second surface of the substrate for each of the one or more second spectral windows; and
converting the spectral information viaapplying a Fourier transform to the second spectral information to recover depth-resolved spectraldepth information about the second surface of the sample at alleach given center wavelengthswavelength simultaneously.
36. The apparatus of claim 35, wherein the processor unit is further adapted to recover size information about the sample by determining a ratio of the first spectroscopic depth-resolved reflection profile and the second spectroscopic depth-resolved reflection profile.
37. The apparatus of claim 35, wherein the first surface is the front of the substrate and the second surface is the back of the substrate or a sample attached to or near the back of the substrate.
38. The method of claim 1, comprising:
providing the one or more spectral windows to the single spectrally-resolved cross-correlated reflection profile as a plurality of spectral windows at a plurality of different center wavelengths to obtain the spectral information for each of the one or more spectral windows; and
applying the Fourier transform to the spectral information to recover the depth-resolved information about the sample at all of the plurality of different center wavelengths simultaneously.
39. The method of claim 17, comprising:
providing the one or more first spectral windows to the first single spectrally-resolved cross-correlated reflection profile as a plurality of spectral windows at a plurality of different center wavelengths to obtain the first spectral information for each of the plurality of spectral windows; and
applying the Fourier transform to the first spectral information to recover the depth-resolved information about the first surface of the substrate at all of the plurality of different center wavelengths simultaneously.
40. The method of claim 17, comprising:
providing the one or more second spectral windows to the second single spectrally-resolved cross-correlated reflection profile as a plurality of spectral windows at a plurality of different center wavelengths to obtain the second spectral information for each of the plurality of spectral windows; and
applying the Fourier transform to the second spectral information to recover the depth-resolved information about the second surface of the substrate at all of the plurality of different center wavelengths simultaneously.
41. The method of claim 17, comprising:
providing the one or more first spectral windows to the first single spectrally-resolved cross-correlated reflection profile as a plurality of first spectral windows at a plurality of different center wavelengths to obtain the first spectral information for each of the plurality of first spectral windows;
providing the one or more second spectral windows to the second single spectrally-resolved cross-correlated profile as a plurality of second spectral windows at the plurality of different center wavelengths to obtain the second spectral information for each of the plurality of second spectral windows;
applying the Fourier transform to the first spectral information to recover the depth-resolved information about the first surface of the substrate at all of the plurality of different center wavelengths simultaneously; and
applying the Fourier transform to the second spectral information to recover the depth-resolved information about the second surface of the substrate at all of the plurality of different center wavelengths simultaneously.
42. The apparatus of claim 20, wherein the processor unit is adapted to:
provide the one or more spectral windows to the single spectrally-resolved cross-correlated reflection profile as a plurality of spectral windows at a plurality of different center wavelengths to obtain the spectral information for each of the plurality of spectral windows; and
apply the Fourier transform to the spectral information to recover the depth-resolved information about the sample at all of the plurality of different center wavelengths simultaneously.
43. The apparatus of claim 35, wherein the processor unit is adapted to:
provide the one or more first spectral windows to the first single spectrally-resolved cross-correlated reflection profile as a plurality of spectral windows at a plurality of different center wavelengths to obtain the first spectral information for each of the plurality of spectral windows; and
apply the Fourier transform to the first spectral information to recover the depth-resolved information about the first surface of the substrate at all of the plurality of different center wavelengths simultaneously.
44. The apparatus of claim 35, wherein the processor unit is further adapted to:
provide the one or more second spectral windows to the second single spectrally-resolved cross-correlated reflection profile as a plurality of spectral windows at a plurality of different center wavelengths to obtain the second spectral information for each of the plurality of spectral windows; and
apply the Fourier transform to the second spectral information to recover the depth-resolved information about the second surface of the substrate at all of the plurality of different center wavelengths simultaneously.
45. The method of claim 2, in which the scatterers are cell nuclei.
46. The method of claim 3, in which the scatterers are cell nuclei.
47. The method of claim 4, in which the scatterers are cell nuclei.
48. The method of claim 21, in which the scatterers are cell nuclei.
49. The method of claim 22, in which the scatterers are cell nuclei.
50. The method of claim 23, in which the scatterers are cell nuclei.
51. The method of claim 1, wherein the bandwidth of at least one of the one or more spectral windows is between approximately 4.4 nm and 21.0 nm.
52. The method of claim 1, wherein the bandwidth of each of the one or more spectral windows is between approximately 4.4 nm and 21.0 nm.
53. The method of claim 17, wherein the bandwidth of at least one of the one or more spectral windows of the first single spectrally-resolved cross-correlated reflection profile is between approximately 4.4 nm and 21.0 nm.
54. The method of claim 17, wherein the bandwidth of at least one of the one or more spectral windows of the second single spectrally-resolved cross-correlated reflection profile is between approximately 4.4 nm and 21.0 nm.
55. The method of claim 48, wherein the bandwidth of at least one of the one or more spectral windows of the first single spectrally-resolved cross-correlated reflection profile is between approximately 4.4 nm and 21.0 nm.
56. The method of claim 17, wherein the bandwidth of each of the one or more spectral windows of the first single spectrally-resolved cross-correlated reflection profile is between approximately 4.4 nm and 21.0 nm.
57. The method of claim 17, wherein the bandwidth of each of the one or more spectral windows of the second single spectrally-resolved cross-correlated reflection profile is between approximately 4.4 nm and 21.0 nm.
58. The apparatus of claim 20, wherein the bandwidth of at least one of the one or more spectral windows is between approximately 4.4 nm and 21.0 nm.
59. The apparatus of claim 20, wherein the bandwidth of each of the one or more spectral windows is between approximately 4.4 nm and 21.0 nm.
60. The apparatus of claim 35, wherein the bandwidth of at least one of the one or more spectral windows of the first single spectrally-resolved cross-correlated reflection profile is between approximately 4.4 nm and 21.0 nm.
61. The apparatus of claim 35, wherein the bandwidth of at least one of the one or more spectral windows of the second single spectrally-resolved cross-correlated reflection profile is between approximately 4.4 nm and 21.0 nm.
62. The apparatus of claim 61, wherein the bandwidth of at least one of the one or more spectral windows of the first single spectrally-resolved cross-correlated reflection profile is between approximately 4.4 nm and 21.0 nm.
63. The apparatus of claim 35, wherein the bandwidth of each of the one or more spectral windows of the first single spectrally-resolved cross-correlated reflection profile is between approximately 4.4 nm and 21.0 nm.
64. The apparatus of claim 35, wherein the bandwidth of each of the one or more spectral windows of the second single spectrally-resolved cross-correlated reflection profile is between approximately 4.4 nm and 21.0 nm.
Description
BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an apparatus and method for obtaining depth-resolved spectra for the purpose of determining structure by measuring elastic scattering properties. More particularly, Fourier domain, low-coherence interferometry techniques are applied to light scattering spectroscopy. This approach permits the viewing and recovery of depth-resolved structures, as well as obtaining spectroscopic information about scattered light as a function of depth.

2. Background of the Related Art

Accurately measuring small objects or other physical phenomena is a goal that is pursued in many diverse fields of scientific endeavor. For example, in the study of cellular biology and cellular structures, light scattering spectroscopy (LSS) has received much attention recently as a means for probing cellular morphology and the diagnosing of dysplasia. The disclosures of the following references are incorporated by reference in their entirety:

    • Backman, V., V. Gopal, M. Kalashnikov, K. Badizadegan, R. Gurjar, A. Wax, I. Georgakoudi, M. Mueller, C. W. Boone, R. R. Dasari, and M. S. Feld, IEEE J. Sel. Top. Quantum Electron., 7(6): p. 887-893 (2001); Mourant, J. R., M. Canpolat, C. Brocker, O. Esponda-Ramos, T. M. Johnson, A. Matanock, K. Stetter, and J. P. Freyer, J. Biomed. Opt., 5(2): p. 131-137 (2000); Wax, A., C. Yang, V. Backman, K. Badizadegan, C. W. Boone, R. R. Dasari, and M. S. Feld, Biophysical Journal, 82: p. 2256-2264 (2002); Georgakoudi, I., E. E. Sheets, M. G. Müller, V. Backman, C. P. Crum, K. Badizadegan, R. R. Dasari, and M. S. Feld, Am J Obstet Gynecol, 186: p. 374-382 (2002); Backman, V., M. B. Wallace, L. T. Perelman, J. T. Arendt, R. Gurjar, M. G. Muller, Q. Zhang, G. Zonios, E. Kline, T. McGillican, S. Shapshay, T. Valdez, K. Badizadegan, J. M. Crawford, M. Fitzmaurice, S. Kabani, H. S. Levin, M. Seiler, R. R. Dasari, I. Itzkan, J. Van Dam, and M. S. Feld, Nature, 406(6791): p. 35-36 (2000); Wax, A., C. Yang, M. Mueller, R. Nines, C. W. Boone, V. E. Steele, G. D. Stoner, R. R. Dasari, and M. S. Feld, Cancer Res, (accepted for publication).

The LSS technique examines variations in the elastic scattering properties of cell organelles to infer their sizes and other dimensional information. In order to measure cellular features in tissues and other cellular structures, it is necessary to distinguish the singly scattered light from diffuse light, which has been multiply scattered and no longer carries easily accessible information about the scattering objects. This distinction or differentiation can be accomplished in several ways, such as the application of a polarization grating, by restricting or limiting studies and analysis to weakly scattering samples, or by using modeling to remove the diffuse component (s).

As an alternative approach for selectively detecting singly scattered light from sub-surface sites, low-coherence interferometry (LCI) has also been explored as a method of LSS. Experimental results have shown that using a broadband light source and its second harmonic allows the recovery of information about elastic scattering using LCI [7].

More recently, angle-resolved LCI (a/LCI) has demonstrated the capability of obtaining structural information by examining the angular distribution of scattered light from the sample or object under examination. The a/LCI technique has been successfully applied to measuring cellular morphology and to diagnosing intraepithelial neoplasia in an animal model of carcinogenesis.

The above references are incorporated by reference herein where appropriate for appropriate teachings of additional or alternative details, features and/or technical background.

SUMMARY OF THE INVENTION

The claimed exemplary embodiments of the present invention address some of the issues presented above.

An object of the invention is to solve at least the above problems and/or disadvantages and to provide at least the advantages described hereinafter.

In one exemplary embodiment of the present invention, an apparatus comprises a first receiver that receives a first reference light and outputs a second reference light. A second receiver that receives a first sample light and outputs a second sample light and wherein the second sample light contains light scattered from a sample when at least a portion of the first sample light is scattered from a sample. A cross-correlator that receives and cross-correlates the second reference light with the second sample light. The cross-correlator may be a spatial cross-correlator.

In another exemplary embodiment of the present invention, a reference arm receives a first reference light and outputs a second reference light. A sample receives a first sample light and outputs a second sample light and wherein the second sample light contains light scattered from the sample when at least a portion of said first sample light is scattered from the sample. A spatial cross-correlator receives and cross correlates the second reference light with the second sample light. The spatial cross-correlator comprises a detector and a processing unit. The detector outputs an interference term to the processing unit. The processing unit processes the interference term to yield depth resolved cross-correlation reflection profiles of the sample. The processing unit first applies a Gaussian window and then a Fourier transform transforms the interference term to yield depth resolved cross-correlation reflection profiles of the sample. The Fourier transform obtains an axial spatial cross-correlation between a signal field(s) and a reference field(s). A light source outputs light, which contains the first sample light and the first reference light.

In another exemplary embodiment of the present invention, a method comprises receiving a first reference light and outputting a second reference light. A first sample light is received and a second sample light is output. The second sample light contains light scattered from a sample when at least a portion of the first sample light is scattered from a sample along with the reception and cross correlation of the second reference light with the second sample light.

In another exemplary embodiment, a method comprises receiving light and splitting at least a portion of the light into reference light and sample light. At least a portion of said reference light is reflected from a reference surface to yield reflected reference light. At least a portion of the sample light is scattered from a sample to yield scattered sample light, and the scattered sample and the reflected reference light are mixed. Information is recovered about the scattered sample light. The mixing comprises detecting an intensity of the scattered sample light and the reflected reference light. Recovering information comprises extracting an interference term from a total intensity. Recovering information can further comprise applying a mathematical operator to the interference term to recover the spectral information about the scattered sample light at a particular depth to yield depth resolved cross-correlation reflection points of the sample. The mathematical operator used is preferably a Gaussian window.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described in detail with reference to the following drawings in which like reference numerals refer to like elements wherein:

FIG. 1A is a diagram of an exemplary embodiment of an fLCI system;

FIG. 1B is a diagram of another exemplary embodiment of an fLCI system using fiber optic coupling;

FIG. 2 is a diagram illustrating exemplary properties of a white light source;

FIG. 3 is a diagram of an exemplary axial spatial cross-correlation function for a coverslip sample;

FIG. 4 is a diagram of exemplary spectra obtained for front and back surfaces of a coverglass sample when no microspheres are present;

FIG. 5 is a diagram of exemplary spectra obtained for front and back surfaces of a coverglass sample when microspheres are present;

FIG. 6 is a diagram of exemplary ratios of spectra in FIGS. 4 and 5 illustrating scattering efficiency of spheres for front and back surface reflections;

FIG. 7 is a diagram of a generalized version of the system shown in FIG. 1;

FIG. 8 is a block diagram of an exemplary embodiment of a method in accordance with the present invention; and

FIG. 9 is a block diagram of another exemplary embodiment of a method in accordance with the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

In the following detailed description of the various exemplary embodiments, reference is made to the accompanying drawings that show, by way of illustration, specific embodiments in which the invention may be practiced. In the drawings, like numerals describe substantially similar components throughout the several views. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. Other embodiments may be utilized without departing from the scope of the present invention. Moreover, it is to be understood that various embodiments of the invention, although different, are not necessarily mutually exclusive. For example, a particular feature, structure, or characteristic described in one embodiment may be included within other embodiments. Therefore, the following detailed description is not to be taken in a limiting sense. The scope of the present invention is delineated by the claims, along with the full scope of equivalents to which such claims are entitled.

The contents of the following references are incorporated by reference in their entirety: Wojtkowski, M., A. Kowalczyk, R. Leitgeb, and A. F. Fercher, Opt. Lett., 27(16): p. 1415-1417 (2002); Wojtkowski, M., R. Leitgeb, A. Kowalczyk, T. Bajraszewski, and A. F. Fercher, J. Biomed. Opt., 7(3): p. 457-463 (2002); Leitgeb, R., M. Wojtkowski, A. Kowalczyk, C. K. Hitzenberger, M. Sticker, and A. F. Fercher, Opt. Lett., 25(11): p. 820-822 (2000).

In general, spectral radar makes use of techniques where depth-resolved structural information is recovered by applying a Fourier transform to the spectrum of two mixed fields. In fLCI, the aforementioned approach used in spectral radar applications is extended to recover not only depth-resolved structure, but also to obtain spectroscopic information about scattered light as a function of depth. The capabilities of fLCI enable extracting the size of polystyrene beads in a sub-surface layer based on their light scattering spectrum. The apparatus and method according to exemplary embodiments of the invention can be applied to many different areas. One such area of application is to recover nuclear morphology of sub-surface cell layers.

One exemplary embodiment of the fLCI scheme is shown in FIG. 1A. White light from a Tungsten light source 100 (e.g. 6.5 W, Ocean Optics™) is coupled into a multimode fiber 101 (e.g. 200 μm core diameter). The output of the fiber 101 is collimated by an achromatic lens 102 to produce a beam 104 (e.g. a pencil beam 5 mm in diameter). The beam 104 is then forwarded to an fLCI system 10.

This illumination scheme achieves Kohler illumination in that the fiber acts as a field stop, resulting in the proper alignment of incident or illuminating light and thereby achieving critical illumination of the sample. In the fLCI system 10, the white light beam is split by the beamsplitter 106 (BS) into a reference beam 105 and an input beam 107 to the sample 108. The light scattered by the sample 108 is recombined at the BS 106 with light reflected by the reference mirror 114 (M).

The reference beam 105 in conjunction with the reference mirror 114 forms a portion of a reference arm that receives a first reference light and outputs a second reference light. The input beam 107 and the sample 108 form a portion of a sample arm that receives a first sample light and outputs a second sample light.

Those skilled in the art will appreciate that the light beam can be split into a plurality of reference beams and input beams (e.g. N reference beams and N input beams) without departing from the spirit and scope of the present invention. Further, the splitting of the beams may be accomplished with a beamsplitter or a fiber splitter in the case of an optical fiber implementation of and exemplary embodiment of the present invention.

In the exemplary embodiment of the present invention shown in FIG. 1A, the combined beam is coupled into a multimode fiber 113 by an aspheric lens 110. Again, other coupling mechanisms or lens types and configurations may be used without departing from the spirit and scope of the present invention. The output of the fiber coincides with the input slit of a miniature spectrograph 112 (e.g. USB2000, Ocean Optics™), where the light is spectrally dispersed and detected.

The detected signal is linearly related to the intensity as a function of wavelength I(λ), which can be related to the signal and reference fields (Es, Er) as:
<I(λ)>=<|Es(λ)|2>+<|Er(λ)|2>+2Re<Es(λ)E*r(λ)>cos φ  (1)
where φ is the phase difference between the two fields and <. . .> denotes an ensemble average.

The interference term is extracted by measuring the intensity of the signal and reference beams independently and subtracting them from the total intensity.

The axial spatial cross-correlation function, ΓSR(z) between the sample and reference fields is obtained by resealing the wavelength spectrum into a wavenumber (k=2π/λ) spectrum then Fourier transforming:
ΓSR(z)=∫dkeikz<Es(k)E*r(k)>cos φ.   (2)

This term is labeled as an axial spatial cross-correlation as it is related to the temporal or longitudinal coherence of the two fields.

Another exemplary embodiment of an fLCI scheme is shown in FIG. 1B. In this exemplary embodiment, fiber optic cable is used to connect the various components. Those skilled in the art will appreciate that other optical coupling mechanisms, or combinations thereof, may be used to connect the components without departing from the spirit and scope of the present invention.

In FIG. 1B, white light from a Tungsten light source 120 is coupled into a multimode fiber 122 and the white light beam in the multimode fiber is split by the fiber splitter (FS) 124 into a reference fiber 125 and an sample fiber 127 to the sample 130. The fiber splitter 124 is used to split light from one optical fiber source into multiple sources.

The reference light in reference fiber 125, in conjunction with a lens 126 (preferably an aspheric lens) and the reference mirror 128, forms a portion of a reference arm that receives a first reference light and outputs a second reference light. Specifically, reference light in reference fiber 125 is directed to the reference mirror 128 by lens 126, and the reference light reflected by the reference mirror 128 (second reference light) is coupled back into the reference fiber 125 with lens 126. The sample light in sample fiber 127 and the sample 130 form a portion of a sample arm that receives a first sample light and outputs a second sample light. Specifically, sample light in sample fiber 127 is directed to the sample 130 by lens 131 (preferably as aspheric lens), and at least a portion of the sample light scattered by the sample 130 is coupled into the sample fiber 127 by lens 131. In the exemplary embodiment shown in FIG. 1B, the sample 130 is preferably spaced from lens 131 by a distance approximately equal to the focal length of lens 131.

At least a portion of the reflected reference light in reference fiber 125 and at least a portion of the scattered sample light on sample fiber 127 are coupled into a detector fiber 133 by the FS 124.

The output of detector fiber 133 coincides with the input of a miniature spectrograph 132, where the light is spectrally dispersed and detected.

FIG. 2 illustrates some of the properties of a white light source. FIG. 2(a) illustrates an autocorrelation function showing a coherence length (lC=1.2 μm). FIG. 2(a) shows the cross-correlation between the signal and reference fields when the sample is a mirror, and this mirror is identical to the reference mirror (M). In this exemplary scenario, the fields are identical and the autocorrelation is given by the transform of the incident field spectrum, modeled as a Gaussian spectrum with center wavenumber ko=10.3 μm−1 and l/e width Δkl/e=2.04 μm−1 (FIG. 2(b)).

FIG. 2(b) shows an exemplary spectrum of light source that can be used in accordance with the present invention.

From this autocorrelation, the coherence length of the field, lc=1.21 μm is determined. This is slightly larger than the calculated width of lc=2/Δkl/c=0.98 μm, with any discrepancy most likely attributed to uncompensated dispersion effects. Note that rescaling the field into wavenumber space is a nonlinear process which can skew the spectrum if not properly executed [13].

In data processing, a fitting algorithm is applied (e.g. a cubic spline fit) to the rescaled wavenumber spectrum and then resampled (e.g. resample with even spacing). The resampled spectrum is then Fourier transformed to yield the spatial correlation of the sample. Those skilled in the art will appreciate that other frequency based algorithms or combinations of algorithms can be used in place of the Fourier transform to yield spatial correlation. One example of a software tool that can be used to accomplish this processing in real time or near real time is to use LabView™ software.

In one exemplary embodiment of the present invention, the sample consists of a glass coverslip (e.g., thickness, d˜200 μm) with polystyrene beads which have been dried from suspension onto the back surface (1.55 μm mean diameter, 3% variance). Thus, the field scattered by the sample can be expressed as:
Es(k)=Efront(k)eik δ z+Eback(k)eik( δ z+nd)   (3)

In equation 3, Efront and Eback denote the field scattered by the front and back surfaces of the coverslip, and δz is the difference between the path length of the reference beam and that of the light reflected from the front surface and n the index of refraction of the glass. The effect of the microspheres will appear in the Eback term as the beads are small and attached closely to the back surface. Upon substituting equation 3 into equation 2, a two peak distribution with the width of the peaks given by the coherence length of the source is obtained.

In order to obtain spectroscopic information, a Gaussian window is applied to the interference term before performing the Fourier transform operation. Those skilled in the art will appreciate that other probabilistic windowing methodologies may be applied without departing from the spirit and scope of the invention. This makes it possible to recover spectral information about light scattered at a particular depth.

The windowed interference term takes the form:
<Es(k)E*r(k)>exp [−((k−kw)/Δkw)2].   (4)

The proper sizing of a windowed interference term can facilitate the processing operation. For example, by selecting a relatively narrow window (Δkw small) compared to the features of Es and Ek, we effectively obtain <Es(kw)E*r(kw) >. In processing the data below, we use Δkw=0.12 μm−1 which degrades the coherence length by a factor of 16.7. This exemplary window setting enables the scattering at 50 different wavenumbers over the 6 μm−1 span of usable spectrum.

In FIG. 3, an axial spatial cross-correlation function for a coverslip sample is showed according to one embodiment of the invention. FIGS. 3(a) and (b) shows the depth resolved cross-correlation reflection profiles of the coverslip sample before and after the processing operations. In FIG. 3(a), a high resolution scan with arrows indicating a peak corresponding to each glass surface is shown. In FIG. 3(b), a low resolution scan is obtained from the scan in FIG. 3(a) is shown by using a Gaussian window.

Note that the correlation function is symmetric about z=0, resulting in a superposed mirror image of the scan. Since these are represented as cross-correlation functions, the plots are symmetric about z=0. Thus the front surface reflection for z>0 is paired with the back surface reflection for z<0, and vice versa.

In FIG. 3(a), the reflection from the coverslip introduces dispersion relative to the reflection from the reference arm, generating multiple peaks in the reflection profile. When the spectroscopic window is applied, only a single peak is seen for each surface, however several dropouts appear due to aliasing of the signal.

To obtain the spectrum of the scattered light, we repeatedly apply the Gaussian window and increase the center wavenumber by 0.12 μm−1 between successive applications. As mentioned above, Δkw=0.12 μm−1 is used to degrade the coherence length by a factor of 16.7. This results in the generation of a spectroscopic depth-resolved reflection profile.

FIGS. 4(a) and (b) show the spectrum obtained for light scattered from the front (a) and back (b) surfaces of a coverglass sample respectively, when no microspheres are present. The reflection from the front surface appears as a slightly modulated version of the source spectrum. The spectrum of the reflection from the rear surface however has been significantly modified. Thus in equation 3, we now take Efront(k)=Es(k) and Eback(k)=T(k)Es(k), where T(k) represents the transmission through the coverslip.

In FIG. 5, the spectra for light scattering obtained for front (a) and back (b) surfaces of a coverglass sample when microspheres are present on the back surface of the coverslip are shown in FIGS. 5(a) and (b). It can be seen that the reflected spectrum from the front surface has not changed significantly, as expected. However, the spectrum for the back surface is now modulated. We can examine the scattering properties S(k) of the microspheres by writing the scattered field as Espheres(k)=S(k)T(k)Es(k) and taking the ratio Espheres(k)/Eback(k)=S(k), which is shown as a solid line in FIG. 6(a). It can be seen from this ratio that the microspheres induce a periodic modulation of the spectrum.

In FIG. 6(a), a ratio of the spectra found in FIG. 4 and FIG. 5 is shown. This illustrates the scattering efficiency of spheres for front (represented by the dashed line) and back (represented by the solid line) surface reflections. In FIG. 6(b), a correlation function obtained from ratio of back surface reflections is shown. The peak occurs at the round trip optical path through individual microspheres, permitting the size of the spheres to be determined with sub-wavelength accuracy.

For comparison, the same ratio for the front surface reflections (dashed line in FIG. 6(a)) shows only a small linear variation. Taking the Fourier transform of S(k) yields a clear correlation peak (FIG. 6(b)), at a physical distance of z=5.24 μm. This can be related to the optical path length through the sphere by z=2nl with the index of the microspheres n=1.59. The diameter of the microspheres to be l=1.65 μm+/−0.33 μm, with the uncertainty given by the correlation pixel size. Thus with fLCI, we are able to determine the size of the microspheres with sub-wavelength accuracy, even exceeding the resolution achievable with this white light source and related art LCI imaging.

There are many applications of the various exemplary embodiments of the present invention. One exemplary application of fLCI is in determining the size of cell organelles, in particular the cell nucleus, in epithelial tissues. In biological media, for example, the relative refractive indices are lower for organelles compared to microspheres and thus, smaller scattering signals are expected. The use of a higher power light source will permit the smaller signals to be detected. Other examples include detection of sub-surface defects in manufactured parts, including fabricated integrated circuits, detection of airborne aerosols, such as nerve agents or biotoxins, and detection of exposure to such aerosols by examining epithelial tissues within the respiratory tract.

Additionally, the larger the size of the nucleus (compared to the microspheres in this experiment), the higher the frequency modulation of the spectrum. Those skilled in the art will appreciate that higher frequency oscillations are detected at a lower efficiency in Fourier transform spectroscopy techniques. Therefore, in order to detect these higher frequency oscillations, a higher resolution spectrograph is used.

FIG. 7 illustrates a generalized embodiment of the fLCI system shown in FIG. 1 and discussed in greater detail above. In FIG. 7, a light source 700 (e.g. a multi-wavelength light) is coupled into an fLCI system 702. Within the fLCI system 702, a sample portion 704 and a reference portion 706 are located. The sample portion 704 includes a light beam and light scattered from a sample. For example, the sample portion 704 may include a sample holder, a free space optical arm, or an optical fiber. The reference portion 706 includes a light beam and light that is reflected from a reference. For example, the reference portion 706 may include an optical mirror. A cross-correlator 708 receives and cross-correlates light from the sample with light from the reference.

FIG. 8 illustrates another exemplary embodiment of the present invention. In FIG. 8, a method is disclosed where a first reference light is received 800 and a second reference light is output 802. A first sample light is received 804 and a second sample light is output 806. The second sample light contains light scattered from a sample when at least a portion of the first sample light is scattered from a sample. The second reference light with the second sample light are received and cross-correlated 808.

FIG. 9 illustrates another exemplary embodiment of the present invention. In FIG. 9, a method is disclosed where light is received 900 from a sample that has been illuminated. At least a portion of the light is split into reference light and sample light 902. At least a portion of said reference light is reflected from a reference surface to yield reflected reference light 904. At least a portion of the sample light is scattered from a sample to yield scattered sample light 906. The scattered sample light and the reflected reference light are mixed 908. Spectral information is recovered about the scattered sample light 910.

The foregoing example illustrates how the exemplary embodiments of the present invention can be modified in various manners to improve performance in accordance with the spirit and scope of the present invention.

From the foregoing detailed description, it should be apparent that fLCI can recover structural information with sub-wavelength accuracy from sub-surface layers based on measuring elastic scattering properties. The simplicity of the system makes it an excellent candidate for probing cellular morphology in tissue samples and may one day serve as the basis for a biomedical diagnostic device.

The foregoing embodiments and advantages are merely exemplary and are not to be construed as limiting the present invention. The present teaching can be readily applied to other types of apparatuses. The description of the present invention is intended to be illustrative, and not to limit the scope of the claims. Many alternatives, modifications, and variations will be apparent to those skilled in the art. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents but also equivalent structures.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US4646722Dec 10, 1984Mar 3, 1987Opielab, Inc.Protective endoscope sheath and method of installing same
US5386817Apr 5, 1993Feb 7, 1995Endomedical Technologies, Inc.Endoscope sheath and valve system
US5489256Nov 2, 1994Feb 6, 1996Adair; Edwin L.Sterilizable endoscope with separable disposable tube assembly
US5534707Oct 8, 1992Jul 9, 1996Beckman Instruments, Inc.Apparatus and method for aligning capillary column and detection optics
US5565986Mar 16, 1995Oct 15, 1996Kn+E,Uml U+Ee Ttel; AlexanderStationary optical spectroscopic imaging in turbid objects by special light focusing and signal detection of light with various optical wavelengths
US5601087Jun 7, 1995Feb 11, 1997Spectrascience, Inc.System for diagnosing tissue with guidewire
US5643175Feb 5, 1996Jul 1, 1997Adair; Edwin L.Sterilizable endoscope with separable disposable tube assembly
US5771327Nov 18, 1996Jun 23, 1998Optical BiopsyOptical fiber probe protector
US5930440Feb 18, 1998Jul 27, 1999Optical Biopsy Technologies, LlcFiber optic probe protector
US5956355 *Jun 17, 1997Sep 21, 1999Massachusetts Institute Of TechnologyMethod and apparatus for performing optical measurements using a rapidly frequency-tuned laser
US6002480 *Jun 2, 1998Dec 14, 1999Izatt; Joseph A.Depth-resolved spectroscopic optical coherence tomography
US6091984Oct 10, 1997Jul 18, 2000Massachusetts Institute Of TechnologyMeasuring tissue morphology
US6134003 *Feb 27, 1996Oct 17, 2000Massachusetts Institute Of TechnologyMethod and apparatus for performing optical measurements using a fiber optic imaging guidewire, catheter or endoscope
US6174291Mar 9, 1998Jan 16, 2001Spectrascience, Inc.Optical biopsy system and methods for tissue diagnosis
US6233373Jun 21, 1999May 15, 2001The United States Of America As Represented By The Secretary Of The NavyOptical spectrometer with improved geometry and data processing for monitoring fiber optic bragg gratings
US6263133Mar 24, 2000Jul 17, 2001Scimed Life Systems, Inc.Optical focusing, collimating and coupling systems for use with single mode optical fiber
US6404497Jan 25, 1999Jun 11, 2002Massachusetts Institute Of TechnologyPolarized light scattering spectroscopy of tissue
US6501551Oct 5, 1999Dec 31, 2002Massachusetts Institute Of TechnologyFiber optic imaging endoscope interferometer with at least one faraday rotator
US6564087Jul 22, 1999May 13, 2003Massachusetts Institute Of TechnologyFiber optic needle probes for optical coherence tomography imaging
US6624890May 24, 2002Sep 23, 2003Massachusetts Institute Of TechnologyPolarized light scattering spectroscopy of tissue
US6697652Jan 19, 2001Feb 24, 2004Massachusetts Institute Of TechnologyFluorescence, reflectance and light scattering spectroscopy for measuring tissue
US6775007Jan 29, 2002Aug 10, 2004Joseph A. IzattFrequency-encoded parallel OCT and associated systems and methods
US6847456Apr 27, 2001Jan 25, 2005Massachusetts Institute Of TechnologyMethods and systems using field-based light scattering spectroscopy
US6853457Sep 4, 2001Feb 8, 2005Forskningscenter RisoOptical amplification in coherence reflectometry
US6863651Oct 19, 2001Mar 8, 2005Visionscope, LlcMiniature endoscope with imaging fiber system
US6879741Nov 4, 2002Apr 12, 2005C Technologies, IncSampling end for fiber optic probe
US7061622Aug 5, 2002Jun 13, 2006Case Western Reserve UniversityAspects of basic OCT engine technologies for high speed optical coherence tomography and light source and other improvements in optical coherence tomography
US7079254Mar 18, 2004Jul 18, 2006Southwest Sciences IncorporatedMethod and apparatus for imaging internal structures of transparent and translucent materials
US7102758May 6, 2003Sep 5, 2006Duke UniversityFourier domain low-coherence interferometry for light scattering spectroscopy apparatus and method
US7355716Jan 24, 2003Apr 8, 2008The General Hospital CorporationApparatus and method for ranging and noise reduction of low coherence interferometry LCI and optical coherence tomography OCT signals by parallel detection of spectral bands
US7366372Feb 27, 2006Apr 29, 2008Honeywell International, Inc.Waveguide device having improved spatial filter configurations
US7391520Jul 1, 2005Jun 24, 2008Carl Zeiss Meditec, Inc.Fourier domain optical coherence tomography employing a swept multi-wavelength laser and a multi-channel receiver
US7417740Nov 12, 2004Aug 26, 2008Medeikon CorporationSingle trace multi-channel low coherence interferometric sensor
US7428050May 13, 2004Sep 23, 2008The University Of AkronMultispectral, multifusion, laser-polarimetric optical imaging system
US7428052Dec 8, 2005Sep 23, 2008Fujinon CorporationOptical tomographic apparatus
US7616323Jan 19, 2006Nov 10, 2009Zygo CorporationInterferometer with multiple modes of operation for determining characteristics of an object surface
US7633627Jan 20, 2006Dec 15, 2009Duke UniversityMethods, systems and computer program products for characterizing structures based on interferometric phase data
US7636168Oct 11, 2006Dec 22, 2009Zygo CorporationInterferometry method and system including spectral decomposition
US7761139Jan 26, 2004Jul 20, 2010The General Hospital CorporationSystem and method for identifying tissue using low-coherence interferometry
US20020143243Jan 19, 2001Oct 3, 2002Massachusetts Institute Of TechnologyFluorescence, reflectance and light scattering spectroscopy for measuring tissue
US20020171831May 24, 2002Nov 21, 2002Massachusetts Institute Of TechnologyPolarized light scattering spectroscopy of tissue
US20030042438Aug 31, 2001Mar 6, 2003Lawandy Nabil M.Methods and apparatus for sensing degree of soiling of currency, and the presence of foreign material
US20030137669Aug 5, 2002Jul 24, 2003Rollins Andrew M.Aspects of basic OCT engine technologies for high speed optical coherence tomography and light source and other improvements in optical coherence tomography
US20040215296Jan 9, 2004Oct 28, 2004Barrx, Inc.System and method for treating abnormal epithelium in an esophagus
US20040223162May 6, 2003Nov 11, 2004Duke UniversityFourier domain low-coherence interferometry for light scattering spectroscopy apparatus and method
US20050004453Jan 26, 2004Jan 6, 2005Tearney Guillermo J.System and method for identifying tissue using low-coherence interferometry
US20050053974May 20, 2004Mar 10, 2005University Of MarylandApparatus and methods for surface plasmon-coupled directional emission
US20060132790Feb 17, 2004Jun 22, 2006Applied Science Innovations, Inc.Optical coherence tomography with 3d coherence scanning
US20060158657Jan 19, 2006Jul 20, 2006De Lega Xavier CInterferometer for determining characteristics of an object surface, including processing and calibration
US20060164643May 13, 2004Jul 27, 2006Giakos George CMultispectral, multifusion, laser-polarimetric optical imaging system
US20060256343Jan 20, 2006Nov 16, 2006Michael ChomaMethods, systems and computer program products for characterizing structures based on interferometric phase data
US20060285635Apr 14, 2006Dec 21, 2006Boppart Stephen AContrast enhanced spectroscopic optical coherence tomography
US20070002327Jul 1, 2005Jan 4, 2007Yan ZhouFourier domain optical coherence tomography employing a swept multi-wavelength laser and a multi-channel receiver
US20070015969Jun 5, 2006Jan 18, 2007Board Of Regents, The University Of Texas SystemOCT using spectrally resolved bandwidth
US20070027391Jul 27, 2006Feb 1, 2007Fujinon CorporationOptical diagnosis and treatment apparatus
US20070086013Oct 11, 2006Apr 19, 2007Zygo CorporationInterferometry method and system including spectral decomposition
US20070133002Oct 11, 2006Jun 14, 2007Duke UniversitySystems and methods for endoscopic angle-resolved low coherence interferometry
US20070165234Oct 14, 2004Jul 19, 2007University Of KentSpectral interferometry method and apparatus
US20070201033Feb 21, 2007Aug 30, 2007The General Hospital CorporationMethods and systems for performing angle-resolved fourier-domain optical coherence tomography
US20080037024May 11, 2007Feb 14, 2008Vadim BackmanSystems, methods, and apparatuses of low-coherence enhanced backscattering spectroscopy
US20080058629Aug 21, 2006Mar 6, 2008University Of WashingtonOptical fiber scope with both non-resonant illumination and resonant collection/imaging for multiple modes of operation
US20080249369Apr 5, 2007Oct 9, 2008University Of WashingtonCompact scanning fiber device
US20080255461Mar 26, 2008Oct 16, 2008Robert WeersinkReal-time optical monitoring system and method for thermal therapy treatment
US20090009759May 14, 2007Jan 8, 2009Vadim BackmanSystems, methods and apparatuses of elastic light scattering spectroscopy and low coherence enhanced backscattering spectroscopy
US20090075391Jun 30, 2008Mar 19, 2009Newton Laboratories, Inc.Spectroscopic diagnostic method and system based on scattering of polarized light
EP0243005A2Mar 24, 1987Oct 28, 1987Dolan-Jenner Industries, Inc.Fiber optic imaging system for on-line monitoring
EP1021126B1Oct 9, 1998Jul 28, 2004Massachusetts Institute Of TechnologyMethod for measuring tissue morphology
WO1999018845A1Oct 9, 1998Apr 22, 1999Vadim BackmanMethod for measuring tissue morphology
WO2000042912A1Jan 25, 2000Jul 27, 2000Vadim BackmanPolarized light scattering spectroscopy of tissue
WO2007133684A2May 11, 2007Nov 22, 2007Vadim BackmanSystems, methods, and apparatuses of low-coherence enhanced backscattering spectroscopy
Non-Patent Citations
Reference
1Amoozegar, Cyrus et a., "Experimental Verification of T-matrix-based Inverse Light Scattering Analysis for Assessing Structure of Spheroids as Models of Cell Nuclei," Applied Optics, vol. 48, No. 10, to be published Apr. 1, 2009, 7 pages.
2Backman, V. et al., "Detection of Preinvasive Cancer Cells," Nature 406, Jul. 6, 2000, pp. 35-36.
3Backman, V. et al., "Measuring Cellular Structure at Submicrometer Scale with Light Scattering Spectroscopy," IEEE J. Sel. Top. Quantum Electron, vol. 7, Issue 6, Nov./Dec. 2001, pp. 887-893.
4Brown, William J. et al., "Review and Recent Development of Angle-Resolved Low-Coherence Interferometry for Detection of Precancerous Cells in Human Esophageal Epithelium," IEEE Journal of Selected Topics in Quantum Electronics, vol. 14, No. 1, Jan./Feb. 2008, pp. 88-97.
5Chalut, Kevin J. et al., "Application of Mie Theory to Assess Structure of Spheroidal Scattering in Backscattering Geometries," J. Opt. Soc. Am. A, vol. 25, No. 8, Aug. 2008, pp. 1866-1874.
6Chalut, Kevin J., et al., "Label-Free, High-Throughput Measurements of Dynamic Changes in Cell Nuclei Using Angle-Resolved Low Coherence Interferometry," Biophysical Journal, vol. 94, Jun. 2008, pp. 4948-4956.
7Choma, Michael A. et al., "Sensitivity Advantage of Swept Source and Fourier Domain Optical Coherence Tomography," Optics Express, vol. 11, No. 18, Sep. 8, 2003, pp. 2183-2189.
8de Boer, Johannes F. et al., "Improved Signal-To-Noise Ratio in Spectral-Domain Compared with Time-Domain Optical Coherence Tomography," Optics Letters, vol. 28, No. 21, Nov. 1, 2003, pp. 2067-2069, http://oa.osa.org/abstract.cfm?id=86605.
9Giacomelli, Michael G. et al., "Application of the T-matrix Method to Determine the Structure of Spheroidal Cell Nuclei with Angle-resolved Light Scattering," Optics Letters, vol. 33, No. 21, Nov. 1, 2008, pp. 2452-2454.
10Graf, R. N. et al., "Parallel Frequency-Domain Optical Coherence Tomography Scatter-Mode Imaging of the Hamster Cheek Pouch Using a Thermal Light Source," Optics Letters, vol. 33, No. 12, Jun. 15, 2008, pp. 1285-1287.
11Hausler, G. et al., "Coherence Radar and Spectral Radar-New Tools for Dermatological Diagnosis," Journal of Biomedical Optics, vol. 3, Jan. 1998.
12Hausler, G. et al., "Coherence Radar and Spectral Radar—New Tools for Dermatological Diagnosis," Journal of Biomedical Optics, vol. 3, Jan. 1998.
13Keener, Justin D. et al., "Application of Mie Theory to Determine the Structure of Spheroidal Scatterers in Biological Materials," Optics Letters, vol. 32, No. 10, May 15, 2007, pp. 1326-1328.
14Kim, Y.L. et al., "Simultaneous Measurement of Angular and Spectral Properties of Light Scattering for Characterization of Tissue Microarchitecture and its Alteration in Early Precancer," IEEE Journal of Selected Topics in Quantum Electronics, vol. 9, Issue 2, Mar./Apr. 2003, pp. 243-256, http://ieeexploreieee-org/xpl/freeabs-all.jsp?tp=&arnumber=1238988&isnumber=27791.
15Kim, Y.L. et al., "Simultaneous Measurement of Angular and Spectral Properties of Light Scattering for Characterization of Tissue Microarchitecture and its Alteration in Early Precancer," IEEE Journal of Selected Topics in Quantum Electronics, vol. 9, Issue 2, Mar./Apr. 2003, pp. 243-256, http://ieeexploreieee—org/xpl/freeabs—all.jsp?tp=&arnumber=1238988&isnumber=27791.
16Leitgeb, R. et al., "Performance of Fourier Domain vs. Time Domain Optical Coherence Tomography," Optics Express, vol. 11, No. 8, Apr. 21, 2003, pp. 889-894.
17Leitgeb, R. et al., "Spectral Measurement of Absorption by Spectroscopic Frequency-Domain Optical Coherence Tomography," Optic Letters, vol. 25, Issue 11, Jun. 1, 2000, pp. 820-822.
18Morgner, U. et al., "Spectroscopic Optical Coherence Tomography," Optic Letters, vol. 25, Issue 2, Jan. 15, 2000, pp. 111-113.
19Pyhtila, John W. et al., "Coherent Light Scattering by In Vitro Cell Arrays Observed with Angle-Resolved Low Coherence Interferometry," SPIE, vol. 5690, 2005.
20Pyhtila, John W. et al., "Determining Nuclear Morphology Using an Improved Angle-Resolved Low Coherence. Interferometry System," Optics Express, vol. 11, No. 25, Dec. 15, 2003.
21Pyhtila, John W. et al., "Fourier-Domain Angle-Resolved Low Coherence Interferometry Through an Endoscopic Fiber Bundle for Light-Scattering Spectroscopy," Optic Letters, vol. 31, No. 6, Mar. 15, 2006.
22Pyhtila, John W. et al., "Polarization Effects on Scatterer Sizing Accuracy Analyzed with Frequency-Domain Angle-Resolved Low-Coherence Interferometry," Applied Optics, vol. 46, No. 10, Apr. 1, 2007.
23Pyhtila, John W. et al., "Rapid, Depth-Resolved Light Scattering Measurements using Fourier Domain, Angle-Resolved Low Coherence Interferometry," Optics Express, vol. 12, No. 25, Dec. 13, 2004.
24Robles, Francisco et al., "Dual Window Method for Processing Spectroscopic OCT Signals with Simultaneous High Spectral and Temporal Resolution," Optical Society of America, 2008, 12 pages.
25Roy, Hemant K. et al., "Four-Dimensional Elastic Light-Scattering Fingerprints as Preneoplastic Markers in the Rat Model of Colon Carcinogenesis," Gastroenterology, vol. 126, Issue 4, Apr. 2004, pp. 1071-1081, http://www.gastrojoumal.org/article/PIIS0016508501000290/abstract.
26Tuchin, V. et al., Tissue Optics: Light Scattering Methods and Instruments for Medical Diagnosis, SPIE, May 2000.
27Wax, Adam et al., "Angular Light Scattering Studies Using Low-Coherence Interferometry," SPIE, vol. 4251, 2001.
28Wax, Adam et al., "Cellular Organization and Substructure Measured Using Angle-Resolved Low-Coherence Interferometry," Biophysical Journal, Apr. 2002, pp. 2256-2264, vol. 82.
29Wax, Adam et al., "Determination of Particle Size Using the Angular Distribtion of Backscattered Light as Measured with Low-Coherence Interferometry," Journal of the Optical Society of America, Apr. 2002, pp. 737-744, vol. 19, No. 4.
30Wax, Adam et al., "Fourier-Domain Low-Coherence Interferometry for Light-Scaterring Spectroscopy," Optic Letters, vol. 28, No. 14, Jul. 15, 2003, pp. 1230-1232.
31Wax, Adam et al., "In Situ Detection of Neoplastic Transformation and Chemopreventive Effects in Rat Esophagus Epithelium Using Angle-Resolved Low-Coherence Interferometry," Cancer Research, Jul. 1, 2003, pp. 3556-3559, vol. 63, No. 13.
32Wax, Adam et al., "Measurement of Angular Distributions by Use of Low-Coherence Interferometry for Light-Scattering Spectroscopy," Optics Letters, Mar. 15, 2001, pp. 322-324, vol. 26, No. 6.
33Wax, Adam et al., "Prospective Grading of Neoplastic Change in Rat Esophagus Epithelium Using Angle-Resolved Low-Coherence Interferometry," Journal of Biomedical Optics, vol. 10(5), Sep./Oct. 2005, pp. 051604-1 through 051604-10.
34Wax, Adam, "Studying the Living Cell Using Light Scattering and Low-Coherence Interferometry," Laser Biomedical Research Center, MIT Spectroscopy Laboratory, presented at Case Western Reserve University 2002, Feb. 1, 2002.
35Wojtkowski, M. et al., "Full Range Complex Spectral Optical Coherence Tomography Technique in Eye Imaging ," Optics Letters, vol. 27, Issue 16, Aug. 15, 2002, pp. 1415-1417.
36Wojtkowski, M. et al., "In Vivo Human Retinal Imaging by Fourier Domain Optical Coherence Tomography," J. Biomed. Opt., vol. 7, No. 3, Jul. 1, 2002, pp. 457-463.
37Xie, Tuqiang et al., "Fiber-Optic-Bundle-Based Optical Coherehence Tomography," Optic Letters, vol. 30, No. 14, Jul. 15, 2005.
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US8233152 *Jul 9, 2009Jul 31, 2012Canon Kabushiki KaishaOptical coherence tomographic imaging method and optical coherence tomographic imaging apparatus
Classifications
U.S. Classification356/497
International ClassificationG01B9/02, G01N15/02
Cooperative ClassificationG01N15/0211
European ClassificationG01N15/02B2
Legal Events
DateCodeEventDescription
Feb 6, 2014FPAYFee payment
Year of fee payment: 8
Sep 20, 2011CCCertificate of correction