Optical waveguides – Optical waveguide sensor
Reexamination Certificate
1998-03-30
2001-01-16
Lee, John D. (Department: 2874)
Optical waveguides
Optical waveguide sensor
C385S024000, C385S116000, C356S329000
Reexamination Certificate
active
06175669
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates generally to guidewires for medical procedures and more particularly to guidewires with optical sensing capabilities.
Optical coherence domain reflectometry (OCDR) is a technique developed by Youngquist et al. in 1987 (Youngquist, R. C. et al., “Optical Coherence-Domain Reflectometry: A New Optical Evaluation Technique,” 1987, Optics Letters 12(3):158-160). Danielson et al. (Danielson, B. L. et al., “Guided-Wave Reflectometry with Micrometer Resolution,” 1987, Applied Physics 26(14): 2836-2842) also describe an optical reflectometer which uses a scanning Michelson interferometer in conjunction with a broadband illuminating source and cross-correlation detection. OCDR was first applied to the diagnosis of biological tissue by Clivaz et al. in January 1992 (Clivaz, X. et al., “High-Resolution Reflectometry in Biological Tissues,” 1992, Optics Letters 17(1):4-6). A similar technique, optical coherence tomography (OCT), has been developed and used for imaging with catheters by Swanson et al. in 1994 (Swanson, E. A. et al., U.S. Pat. Nos. 5,321,501 and 5,459,570). Tearney et al. (Tearney, G. J. et al., “Scanning Single-Mode Fiber Optic Catheter-Endoscope for Optical Coherence Tomograph,” 1996, Optics Letters 21(7):543-545) also describe an OCT system in which a beam is scanned in a circumferential pattern to produce an image of internal organs. U.S. Pat. No. 5,570,182 to Nathel et al. describes method and apparatus for detection of dental caries and periodontal disease using OCT. However, as OCT systems rely on mechanical scanning arms, miniaturizing them enough to operate on a guidewire would be very difficult.
Polarization effects in an OCDR system for birefringence characterization have been described by Hee et al. (Hee, M. R. et al., “Polarization-sensitive low-coherence reflectometer for birefringence characterization and ranging,” J. Opt. Soc. Am. B, Vol. 9, No. 6, June 1992, 903-908) and in an OCT system by Everett et al. (Everett, M. J. et al., “Birefringence characterization of biological tissue by use of optical coherence tomography,” Optics Letters, Vol. 23, No. 3, Feb. 1, 1998, 228-230).
In a prior art OCDR scanning system
10
, shown in
FIG. 1
, light from a low coherence source
12
is input into a 2×2 fiber optic coupler
14
, where the light is split and directed into sample arm
16
and reference arm
18
. An optical fiber
20
is connected to the sample arm
16
and extends into a device
22
, which scans an object
24
. Reference arm
18
provides a variable optical delay. Light input into reference arm
18
is reflected back by reference mirror
26
. A piezoelectric modulator
28
may be included in reference arm
18
with a fixed mirror
26
, or modulator
28
may be eliminated by scanning mirror
26
in the Z-direction. The reflected reference beam from reference arm
18
and a reflected sample beam from sample arm
16
pass back through coupler
14
to detector
30
(including processing electronics), which processes the signals by techniques that are well known in the art to produce backscatter profile (or “image”) on display
32
.
SUMMARY OF THE INVENTION
This invention is a guidewire with sensing capabilities based on a multiplexed optical coherence domain reflectometer (OCDR), which allow it to sense location, thickness, and structure of the arterial walls or other intra-cavity regions as it travels through the body during minimally invasive medical procedures. This information will be used both to direct the guidewire through the body by detecting vascular junctions and to evaluate the nearby tissue. The guidewire contains multiple optical fibers which couple light from the proximal to distal end. Light from the fibers at the distal end of the guidewire is directed onto interior cavity walls via small diameter optics, such as gradient index lenses and mirrored corner cubes. The light reflected or scattered from the cavity walls is then collected by the fibers which are multiplexed at the proximal end to the sample arm of an optical low coherence reflectometer. The resulting data, collected sequentially from the multiple fibers, provides information about branching of arteries necessary for guiding the guidewire through the arterial system. It also can be used to locate small structural abnormalities in the arterial or cavity wall (such as aneurysms or arteriovenous malformations) that are currently not resolvable by existing techniques. The guidewire can also be used in nonmedical applications.
By multiplexing between a number of sensor fibers with an optical switch, the OCDR system of the invention has multiple sequentially accessed sensor points consisting of the tip of each multiplexed fiber. These sensor points measure the scattering of light as a function of distance from the fiber tip, thus determining both the distance between the fiber tip and the nearest tissue and any structure in that tissue. For guiding purposes, a number of these fibers are embedded in the guidewire with their tips at the distal end of the guidewire. Miniature collimating and reflection optics deflect the light from the fiber tips toward the vascular walls, thus sensing any branching of the vasculature or abnormalities in the walls.
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patent: 5268741 (1993-12-01), Chou et al.
patent: 5321501 (1994-06-01), Swanson et al.
patent: 5453827 (1995-09-01), Lee
patent: 5459570 (1995-10-01), Swanson et al.
patent: 5491524 (1996-02-01), Hellmuth et al.
patent: 5835642 (1998-11-01), Gelikonov et al.
patent: 5901261 (1999-05-01), Wach
patent: 5911017 (1999-06-01), Wach et al.
patent: 0484913 (1992-05-01), None
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patent: WO 97/32182 (1997-09-01), None
Hee et al., Polarization -sensitive low-coherence reflectometer for birefringence characterization and ranging, Journal of Optical Society of America B, vol. 9, No. 6, pp. 903-908, Jun. 1992.
Tearney et al., “Scanning single-mode fiber optic catheter-endoscope for optical coherence tomography”, Optics Letters vol. 21, No. 7, p. 543-545, Apr. 1, 1996.
Hee et al., “Polarization-sensitive low-coherence reflectometer for birefringence characterization and ranging”, Journal of Optical Society of America B, vol. 9, No. 6, p. 903-908, Jun. 1992.
Colston Billy W.
Da Silva Luiz B.
Everett Matthew
Matthews Dennis
Connelly-Cushwa Michelle R.
Lee John D.
The Regents of the Universtiy of California
Thompson Alan H.
Wooldridge John P.
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