U.S. patent application number 14/584474 was filed with the patent office on 2015-04-30 for arrangements, devices, endoscopes, catheters and methods for performing optical imaging by simultaneously illuminating and detecting multiple points on a sample.
The applicant listed for this patent is The General Hospital Corporation. Invention is credited to Brett Eugene Bouma, Johannes F. de Boer, Guillermo J. Tearney.
Application Number | 20150116726 14/584474 |
Document ID | / |
Family ID | 36086719 |
Filed Date | 2015-04-30 |
United States Patent
Application |
20150116726 |
Kind Code |
A1 |
Tearney; Guillermo J. ; et
al. |
April 30, 2015 |
ARRANGEMENTS, DEVICES, ENDOSCOPES, CATHETERS AND METHODS FOR
PERFORMING OPTICAL IMAGING BY SIMULTANEOUSLY ILLUMINATING AND
DETECTING MULTIPLE POINTS ON A SAMPLE
Abstract
Devices, arrangements, endoscopes, catheters and methods adapted
to propagate at least one electro-magnetic radiation are provided.
In particular, a waveguide apparatus specifically configured may be
utilized to split the electro-magnetic radiation into a plurality
of beams that are intended to illuminate a biological sample, and
impart a unique associated characteristic unto each of the beams.
The beams may be intended to illuminate a biological sample at
distinct locations, and impart a unique associated characteristic
unto each of the beams. In addition, a control apparatus may be
provided which is configured to control at least one of the fibers
and which can be input to the fibers so as to modify the unique
associated characteristics of the beams being propagated along the
fibers, and thereby modify the characteristics of the distinct
locations on the sample.
Inventors: |
Tearney; Guillermo J.;
(Cambridge, MA) ; de Boer; Johannes F.;
(Amstelveen, NL) ; Bouma; Brett Eugene; (Quincy,
MA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
The General Hospital Corporation |
Boston |
MA |
US |
|
|
Family ID: |
36086719 |
Appl. No.: |
14/584474 |
Filed: |
December 29, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11288994 |
Nov 29, 2005 |
8922781 |
|
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14584474 |
|
|
|
|
60631539 |
Nov 29, 2004 |
|
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Current U.S.
Class: |
356/479 |
Current CPC
Class: |
G02B 21/0032 20130101;
G02B 23/26 20130101; A61B 5/0073 20130101; A61B 5/6852 20130101;
G02B 21/0056 20130101; G01B 9/02001 20130101; G01B 9/02091
20130101; G02B 23/2453 20130101; G02B 23/2469 20130101; A61B 5/0066
20130101 |
Class at
Publication: |
356/479 |
International
Class: |
G02B 23/24 20060101
G02B023/24; G01B 9/02 20060101 G01B009/02 |
Claims
1-30. (canceled)
31. An arrangement adapted to propagate at least one
electro-magnetic radiation, comprising: a waveguide apparatus which
includes a structure that is specifically configured to split the
at least one electro-magnetic radiation into a plurality of beams
that are intended to illuminate a biological sample, wherein the
waveguide apparatus includes a circularly-cylindrical waveguide;
and a computer processing arrangement configured to receive
information regarding the beams, and generate at least one image of
at least one portion of the biological sample based on the
information.
32. The arrangement according to claim 31, wherein the structure is
specifically configured to impart at least one unique associated
characteristic unto each of the beams.
33. The arrangement according to claim 31, wherein the beams have a
substantially the same wavelength.
34. The arrangement according to claim 31, wherein the beams
produce orders of rings on the biological sample.
35. The arrangement according to claim 31, wherein the
circularly-cylindrical waveguide is at least one fiber.
36. A method for propagating at least one electro-magnetic
radiation, comprising: using a structure of a waveguide apparatus,
split the at least one electro-magnetic radiation into a plurality
of beams that are intended to illuminate a biological sample,
wherein the structure includes a circularly-cylindrical waveguide;
and using a computer processing arrangement, receiving information
regarding the beams, and generating at least one image of at least
one portion of the biological sample based on the information.
37. The method according to claim 36, further comprising, with the
structure, imparting at least one unique associated characteristic
unto each of the beams.
38. The method according to claim 36, wherein the beams have a
substantially the same wavelength.
39. The method according to claim 36, further comprising, with the
beams, producing orders of rings on the biological sample.
40. The method according to claim 36, wherein the
circularly-cylindrical waveguide is at least one fiber.
Description
CROSS-REFERENCE TO RELATED APPLICATION(S)
[0001] This application is based upon and claims the benefit of
priority from U.S. Patent Application Ser. No. 60/631,539, filed
Nov. 29, 2004, the entire disclosure of which is incorporated
herein by reference.
FIELD OF THE INVENTION
[0002] The present invention relates to optical imaging, and more
particularly devices and methods which are capable of performing
optical imaging by simultaneously illuminating and detecting
multiple points on a sample.
BACKGROUND OF THE INVENTION
[0003] Endoscopic/catheter-based optical imaging techniques that
utilize beam scanning to form an image such as optical coherence
tomography and confocal microscopy, may be limited by an inability
to rapidly scan a beam along one or two dimensions. The reason for
this is that likely the only reliable methods for rapid optical
scanning should be performed in free space. In addition, the size
of these optical scanners may deter their use in small probes, such
as in endoscopes or catheters. The capability to miniaturize the
scanning mechanism would likely increase the number of medical
applications of optical imaging techniques to include all surfaces
of the body, gynecologic applications, probe based applications,
and internal organ systems.
[0004] U.S. Pat. No. 5,321,501 describes optical coherence
tomography and U.S. Pat. No. 5,161,053 describes confocal
microscopy, both of which utilize an optical fiber. However, the
conventional methods described in these publications disclose the
use of a single focused spot on the sample with an arrangement for
scanning such spot. U.S. Pat. No. 5,659,642 describes the use of an
optical fiber bundle to perform confocal microscopy. However, this
publication also describes a switching arrangement for selectively
illuminating individual channels. In the disclosure of this U.S.
patent, a fiber bundle are used, with all points being illuminated
and detected simultaneously, thereby eliminating the need for a
switching mechanism for selectively illuminating certain channels.
Endoscopic confocal microscopy technology has been proposed as a
new diagnostic imaging technology capable of providing cellular
resolution images in vivo. However, these proposed technology have
not been easily realized using a single optical fiber due to the
inability to develop a rapid beam scanning mechanism that can
reside in a small diameter probe. Other approaches that have been
used are selectively illuminating optical fibers in a fiber bundle
by scanning a focused beam at the proximal end of a fiber bundle.
These approaches have various difficulties due to a beam overlap
between channels, thus causing two points to be illuminated
simultaneously, which results in cross-talk and aberrations. It
would be desirable to use a single fiber to perform endoscopic
confocal imaging. If a fiber bundle is used, it may be preferable
to illuminate multiple points simultaneously, so that each fiber is
illuminated by a unique spot centered on the individual fiber
cores.
[0005] Optical coherence tomography ("OCT") is an imaging modality
that has been implemented in the internal organs of patients using
optical fibers. FIG. 1 shows an exemplary mechanical and associated
optical elements that are common to particular OCT catheter
designs. These catheter designs may include an inner core 120,
which can may contain a fiber optic element 115 that is coupled to
the OCT system at the proximal end 110, 100, and which can focus
and redirect the light at the distal end 150. The inner core 120
can rotate or translate to provide one-dimensional motion of the
distal optics that serves to scan the beam on the sample. The inner
core is enclosed in a transparent sheath 130.
[0006] The use of catheters in OCT that utilize motion transduction
from a proximal actuator to the distal optics by an inner core is
problematic due to artifacts that may occur when friction between
the inner core and outer transparent sheath causes non-uniform
rotation or linear motion 200. This friction may cause linear
artifacts that become more noticeable as the resolution of the
imaging technology is increased. As a result, these non-uniform
transduction artifacts may prevent the use of this type of catheter
when ultra-high resolution OCT (e.g., 1 .mu.m) becomes clinically
available. Additional friction due to catheter bending or rotation
during the procedure may further exacerbate the problem.
OBJECTS AND SUMMARY OF THE INVENTION
[0007] One of the objects of the present invention is to overcome
the above-described deficiencies and problems, and provide an
exemplary embodiment of a device and arrangement for simultaneously
illuminating multiple points on a sample that can be miniaturized
and incorporated into a compact probe. Each point on the sample is
encoded by frequency using an exemplary embodiment of a frequency
encoding method according to the present invention. As a result,
frequency analysis of the signal reflected or transmitted through
the sample may allow a reconstruction of an image representing the
interaction between the energy input and the sample. In addition,
by allowing light delivery through a single optical fiber, this
device may be also be incorporated into catheters or endoscopes.
Other advantages of this exemplary embodiment of the device may
include a lack of moving parts, heterodyne detection, and the
potential for obtaining cross-sectional images. These properties
promote this device for use in performing optical diagnostic
imaging in all accessible surfaces of the body. As an example, two
technologies that can use and/or incorporate this device are
endoscopic confocal microscopy and optical coherence
tomography.
[0008] Using another exemplary embodiments of the device and method
according to the present invention, multiple spots may be
illuminated on the sample simultaneously, and can be detected
simultaneously, thus possibly eliminating the need for scanning a
single spot.
[0009] Therefore, exemplary embodiments of devices, arrangements,
catheters and methods adapted to propagate at least one
electro-magnetic radiation are provided. In particular, a waveguide
apparatus specifically configured may be utilized to separate or
split the electro-magnetic radiation into a plurality of beams that
are intended to illuminate a biological sample, and impart a unique
associated characteristic unto each of the beams. The beams may be
intended to illuminate a biological sample at distinct locations,
and impart a unique associated characteristic unto each of the
beams. In addition, a control apparatus may be provided which is
configured to control at least one of the fibers and which can be
input to the fibers so as to modify the unique associated
characteristics of the beams being propagated along the fibers, and
thereby modify the characteristics of the distinct locations on the
sample.
[0010] For example, the waveguide can be a multi-mode waveguide
and/or a mirror tunnel. A first illumination arrangement may also
be provided that receives the at least one electro-magnetic
radiation, and produces a first radiation at least one of within
and in a close proximity to the waveguide apparatus. A second
illumination arrangement can also be provided that receives which
produces a plurality of second radiations based on the first
radiation. The second radiations may be approximations of the first
radiation, and/or provided at distinct locations on a sample. The
first illumination arrangement may include an optical fiber and/or
a lens.
[0011] According to another exemplary embodiment of the present
invention, a further apparatus can be provided which is configured
to control the waveguide apparatus so as to modify the unique
associated characteristics of the beams. The unique associated
characteristics may include path-lengths and/or phases of the
respective beams. The further apparatus can control the waveguide
apparatus by modifying structural characteristics of the waveguide
apparatus. The modification of the structural characteristics of
the waveguide apparatus may be asymmetric with respect to a
cross-section of the waveguide apparatus. The further apparatus may
control the waveguide apparatus by modifying optical
characteristics of the waveguide apparatus. The optical
characteristics can include a refractive index.
[0012] Further, the second illumination arrangement can include a
further illumination arrangement which is configured to arrange the
second radiation in a predetermined pattern on the sample. The
predetermined pattern may be approximately circular. The waveguide
apparatus can include a plurality of fibers which are configured to
transmit the beams. A control apparatus may further be provided
that is configured to control the fibers and/or inputs to the
fibers so as to modify the unique associated characteristics of the
beams being propagated along the fibers, and thereby modify the
characteristics of the distinct locations on the sample. Third
radiations reflected from the sample may be transmitted back
through the waveguide apparatus, and can be based on the second
radiation. A reference arm section may be provided that is
configured to propagate a portion of the electro-magnetic radiation
which is intended to be forwarded to a reference.
[0013] According to still another exemplary embodiment of the
present invention, a combining apparatus may be provided which
combines the third radiation and a fourth radiation returned from
the reference arm to produce an interference radiation. A detection
apparatus can be provided which is configured to detect the
interference radiation. Further, a processing apparatus may be
provided which is configured to generate data corresponding to the
third radiations returning from the distinct locations on the
sample based on the interference radiation. The processing
apparatus may be further configured to generate an image of at
least one portion of the sample based on the data. The
electro-magnetic radiation can be generated by a narrowband light
source that has a tunable center wavelength. The electro-magnetic
radiation may be generated by a broadband light source, and the
second radiation returned from the waveguide apparatus and a
radiation returned from the reference arm section may be adapted to
be received by a spectrometer apparatus. A probe (e.g., a catheter,
endoscope and/or laparoscope) may be included which houses the
waveguide apparatus.
[0014] These and other objects, features and advantages of the
present invention will become apparent upon reading the following
detailed description of embodiments of the invention, when taken in
conjunction with the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] Further objects, features and advantages of the invention
will become apparent from the following detailed description taken
in conjunction with the accompanying figures showing illustrative
embodiments of the invention, in which:
[0016] FIG. 1 is a side cut-away view of a conventional OCT
catheter;
[0017] FIG. 2 is an OCT image using the conventional OCT catheter
of FIG. 1 that is acquired from a subject with Barrett's esophagus,
which shows a non-uniform linear motion artifact;
[0018] FIG. 3 is a schematic side view of a frequency encoded
multiple beam OCT system according to one exemplary embodiment of
the present invention; with the reference arm mirror potentially
moving in a time domain ("TD")-OCT or may remain fixed for a
spectral domain ("SD")-OCT or optical frequency domain imaging
("OFDI") techniques;
[0019] FIG. 4 is a schematic side view of a multiple beam optical
imaging system according to another exemplary embodiment of the
present invention, which includes a single mode fiber and multiple
beam generating element at the distal end of a catheter;
[0020] FIG. 5 is a schematic side view of a multiple beam optical
imaging system according to still another exemplary embodiment of
the present invention, which includes a fiber array and multiple
beam generating element at a proximal end of the catheter;
[0021] FIG. 6 is an enlarged schematic view of an exemplary
embodiment of a multiple spot generating ("MSG") device according
to the present invention that includes two mirrors;
[0022] FIG. 7 is an enlarged schematic view of another exemplary
embodiment of the MSG device that can be used to generate a
circumferential scan pattern;
[0023] FIG. 8 is a side schematic view of an exemplary embodiment
of a fiber optic arrangement according to the present invention
which can be used for modulating purposes for each separate beamlet
on the sample; and
[0024] FIG. 9 is a side schematic view of another exemplary
embodiment of the fiber optic arrangement for synthetic aperture
beam scanning.
[0025] Throughout the figures, the same reference numerals and
characters, unless otherwise stated, are used to denote like
features, elements, components or portions of the illustrated
embodiments. Moreover, while the present invention will now be
described in detail with reference to the figures, it is done so in
connection with the illustrative embodiments.
DETAILED DESCRIPTION
[0026] The present invention provides exemplary variations of a
catheter paradigm that generally does not scan the beam at the
distal end of the catheter, thus eliminating the potential for
non-uniform motion artifacts. In a conventional OCT system, one way
for conducting OCT can be based on time domain OCT (TD-OCT)
scanning.
[0027] In thus exemplary procedure, the length of the reference arm
in an interferometer 325 is rapidly scanned over a distance
corresponding to the imaging depth range (as shown in FIG. 3),
producing an interference pattern when the path length of the
reference arm matches the pathlength to a given scatterer in the
sample arm to within the temporal coherence length of the source
310 light. For TD-OCT technique, broad bandwidth light 310 can be
input into an interferometer, and separate or split into a
reference arm 325 and a sample arm 345 arm. The optical path length
of the reference arm is scanned by translating the reference arm
mirror 320. Light returned from the reference and sample arms 325,
345 combine at the splitter 330. Interference fringes may be
detected when the sample arm path length matches the reference arm
path length to within the coherence length of the light. The
detection of the fringe patterns may allow one axial scan (A-line)
to be constructed that maps tissue reflectivity to a given axial or
depth location. An image can be generated by repeating this process
at successive transverse locations on the sample.
[0028] In conventional OCT techniques, one single spot may be
illuminated on the sample at one time. According to an exemplary
embodiment of the present invention, instead, multiple beams 370
can be focused by the distal optics simultaneously illuminating one
transverses dimension on the sample 360. Each distinct beam or spot
on the sample 360 can be encoded by frequency in a manner such that
frequency analysis of the interferometric signal provides
reconstruction of the entire OCT image. Another advantage of this
exemplary OCT paradigm is that the reference arm path length
scanning can be performed at a much slower rate, thus allowing
conventional mechanical path length scanning techniques to produce
OCT images at real time frame rates.
Exemplary System Overview
[0029] A side schematic view of an exemplary embodiment of a system
according to the present invention is shown in FIGS. 4 and 5. For
example, each device can include an irradiation source 400, 500, a
sample path (impacting the sample 460, 560) and a reference path
(impacting a reference 410, 510) and a detector 470, 570. A
catheter 430 of FIG. 4 may contain a single optical fiber 435 with
the multiple spot generating ("MSG") device 440 at the distal end
of the catheter. Alternatively, the MSG device 580 of FIG. 5 may be
placed at the proximal end of the catheter 530, illuminating an
optical fiber array 535. Multiple points 450, 550 are thus
illuminated on the sample 460, 560.
Multiple Spot Generating ("MSG") Device
[0030] An enlarged view of a schematic diagram of one exemplary
embodiment of the MSG device according to the present invention is
shown in FIG. 6. A beam emitted from an optical fiber 600 diverges
by focusing it to a spot by a lens 610 at the input to a mirror
tunnel or optical waveguide 630, 640. A lens at the opposite end
650 of the mirror tunnel images virtual sources or beamlets along a
one-dimensional line. Light is reflected from the sample 660, and
returns along its conjugate path. The exemplary embodiment of the
optical system according to the present invention provides a
confocal rejection of out-of-focus light, due to the aperture of
the fiber.
[0031] Due to the geometry of this exemplary optical device, light
that forms each beamlet (I.sub.n) 670 bounces off one of the
mirrors n times. This same beamlet reflects off of the opposite
mirror n-1 times. If one or both mirrors 630, 640 are moved using
an electromechanical actuator, such as a piezoelectric transducer,
each distinct beamlet can be imparted a phase shift, nv.sub.d,
where v.sub.d is the Doppler shift imparted by a double-passed
reflection off one moving mirror:
v d = 4 v .lamda. . ##EQU00001##
[0032] Heterodyne detection of the signal returned from the probe
can allow a simultaneous measurement of the Doppler shifted
frequencies 0, v.sub.d, 2 v.sub.d . . . nv.sub.d. The reflectivity
from each point can be determined using a tapped bandpass filter or
ramped frequency mixing demodulation. The bandwidth of the signal
must be no greater than 1/2 v.sub.d to avoid aliasing.
Brief Description of Components of Exemplary Device of FIG. 6
[0033] Lens 610: GRIN, cylindrical, plano-convex, convex-convex,
drum, ball, asphere, multiple element. Asymmetric holographic
diffuser.
[0034] Mirrors 630 and/or 640: Dielectric, omnidirectional mirrors,
uncoated metal
[0035] Mirror motion mechanism 635: Piezoelectric transducer,
cantilever.
[0036] Lens 650: GRIN (OCT), plano-convex, convex-convex, drum,
ball, asphere, multiple element (confocal).
Conjugate Symmetry
[0037] The exemplary two-mirror system described above with
reference to FIG. 6 has conjugate symmetry properties. Positive and
negative beamlets of the same order may have the same Doppler shift
if both mirrors are synchronous and have identical modulation
frequencies. Discrimination of positive and negative orders may be
accomplished by modulating the two mirrors 630, 640 with different
phases and performing phase sensitive detection. Alternatively,
each positive and negative order may be discriminated by frequency
interleaving by modulating each mirror at a different
frequency.
Alternative Mirror Configurations
[0038] Two mirror (N=2) device can create a one-dimensional array
of beamlets.
[0039] Triangular mirror tunnel (N=3) can create a two-dimensional
hexagonal array of beamlets.
[0040] Rectangular array (N=4) can create a rectilinear array of
beamlets.
[0041] Higher orders (N=5,6) can create more complex
two-dimensional patterns.
[0042] Cylindrical waveguide may produce orders of rings on the
sample.
[0043] The use of N=2 mirrors may have the advantage that the
aspect ratio can be maintained at 1:1. In addition, this exemplary
configuration allows the illumination of a two-dimensional area,
which is particularly well suited for endoscopic confocal
microscopy. Disadvantages of two-dimensional illumination may
include an increased complexity of the detection mechanism and an
increased high reflectivity requirements for the mirror
coatings.
Exemplary Embodiment of Device (with N=2 Configuration)
[0044] Using a mirror separation (d) of 10 a mirror length, L, of
2.0 mm, and a input divergence angle of 100.degree., a total of 520
points may be simultaneously illuminated and detected using the
exemplary embodiment of the present invention. Assuming a mirror
reflectivity of 0.997, the maximum double-pass accumulated loss at
the edge of the scan would be 6.0 dB. Specifying dielectric
coatings that provide maximal reflection at the higher angles may
minimize this loss.
Endoscopic Confocal Applications
[0045] For example, N=2 configurations may be used in conjunction
with SECM for providing the slow scan axis of SECM. The exemplary
MSG device (with N=2) can also be used to provide the fast scan
axis for endoscopic confocal microscopy. One beneficial option can
be the use of N>2 configurations, which may provide the entire
two-dimensional scan.
Cross Talk
[0046] Cross talk can occur every (2M+1) pixels on the sample.
Modulating M mirrors can allow interleaving of the cross-talk
frequencies. Since cross talk exists between (2M++) illumination
spots on the sample, increasing N and modulating all N=M mirrors
allows increasing separation of the cross-talk channels with
increasing N and M. For example, for N=M=2, cross talk occurs for
spots that are 4 spot diameters from each other. If N=M is
increased to 3, cross-talk occurs for spots that are 6 diameters
from each other. Cross talk may also be reduced by increasing
spot-spot separation or illuminating 1/N of the mirror tunnel and
modulating only one mirror.
MSG Spot Symmetry
[0047] When MSG illumination is in the center of the exemplary MSG
device, identical frequency shifts and path length variations occur
symmetrically around the center of the MSG. In order to avoid spot
order ambiguity, these planes of symmetry must be broken.
[0048] One way for breaking this symmetry is to illuminate the MSG
device at a location slightly offset from the center. Another way
of breaking this symmetry may be to utilize mirrors of slightly
different lengths or angulation.
Electro-Optical Exemplary Embodiments of Device
[0049] In the above descriptions, the use of a hollow, mirror-based
waveguide has been described for generating multiple spots on the
sample. An alternative exemplary embodiment of the present
invention can use a silicon/glass/crystal waveguide, which would
also produce the self-imaging effect. The waveguide may also
contain an electro-optic material where a voltage applied to the
crystal would change the extraordinary and ordinary refractive
indices in such a manner as to modulate the phase of the different
spot orders independently. This may have the same effect as
physically modulating the mirror distances.
Optical Coherence Tomography Applications
[0050] In standard axial (depth) priority scan OCT, the MSG device
can be used to provide the slow scan axis within the OCT probe.
This can allow for imaging at the distal end of the OCT probe,
eliminating artifacts such as binding and non-uniform rotational
defects ("NURD") found using a cable to transduce motion from the
proximal to distal ends of the catheter/endoscope probe.
[0051] Since the MSG device is capable of rapid imaging, the
priority of OCT can be modified from axial to transverse. This
exemplary variant of the present invention can greatly diminish the
requirements of the rapidly scanning optical delay line ("RSOD"),
which could increase scan speeds of OCT systems significantly.
Exemplary OCT Circumferential Imaging Catheter Design
[0052] An incorporation of a spatially varying directional grating
760 could allow circumferential OCT imaging with an elimination of
non-uniform motion (as shown in the enlarged schematic view of the
exemplary MSG device of FIG. 7). This grating may take a line or
two-dimensional array of Doppler encoded beamlets and maps this
pattern into a circle 770. The application of this exemplary
technique may be desirable for OCT imaging of coronary arteries.
Another exemplary embedment of the present invention that enables
the circumferential imaging with the MSG device includes the
insertion of a helical mirror in place of the custom grating 760 of
FIG. 7.
Alternate Exemplary Embodiment of MSG Device
[0053] Another exemplary embodiment of the MSG device according to
the present invention, as shown in FIG. 8, can include a single
fiber input 800 provided into a star coupler 810 or multiple fibers
820 arranged such that each fiber received a separate Doppler
frequency. The Doppler frequencies may be applied using
piezoelectric fiber stretchers, electro-optic or acustooptic
modulators 830. Each individual fiber can then be directed to focus
a single spot on the sample 850 by distal optics 855, each unique
spot encoded by frequency.
Synthetic Aperture Beam Scanning for OCT and Confocal
Microscopy
[0054] Another exemplary embodiment for use with OCT or confocal
imaging according to the present invention that excludes a
transverse scanning mechanism may use a one- or two-dimensional
fiber array 935 where the phase of light in each fiber could be
controlled 930 or 960 (as shown in FIG. 9). An arrangement for
controlling the phase of light in each fiber can include mechanical
manipulation of the individual fibers (e.g. piezoelectric
transducers) or phase control of each fiber at the input of the
array (e.g. via liquid crystal spatial light modulator). By
controlling the phase of each individual channel, the output from
each fiber can interfere with the outputs from other fibers in
order to create a focus or multiple foci 950 on the sample, which
can then be scanned. A circumferential scan can be conducted by
insertion of a diffractive optic or helical mirror distal to the
fiber bundle face at the end of the catheter/endoscope.
Detection
[0055] A high sensitivity may be achieved through the use of
heterodyne detection. If the reference arm 410 is modulated, the
interference of light from the sample arm and the reference arm
will also be modulated. High signal to noise ratios may be then
achieved by lock-in detection on the reference arm modulation
frequency. Frequency domain techniques such as SD-OCT and OFDI can
also be utilized that would detect different spectral interference
fringe frequencies for different spot orders, as a result of their
different path length traveled through the MSG.
[0056] The foregoing merely illustrates the principles of the
invention. Various modifications and alterations to the described
embodiments will be apparent to those skilled in the art in view of
the teachings herein. Indeed, the arrangements, systems and methods
according to the exemplary embodiments of the present invention can
be used with any OCT system, OFDI system or other imaging systems,
and for example with those described in U.S. Provisional Patent
Appn. No. 60/514,769 filed Oct. 27, 2003, and International Patent
Application No. PCT/US03/02349 filed on Jan. 24, 2003, the
disclosures of which are incorporated by reference herein in their
entireties. It will thus be appreciated that those skilled in the
art will be able to devise numerous systems, arrangements and
methods which, although not explicitly shown or described herein,
embody the principles of the invention and are thus within the
spirit and scope of the present invention. In addition, to the
extent that the prior art knowledge has not been explicitly
incorporated by reference herein above, it is explicitly being
incorporated herein in its entirety. All publications referenced
herein above are incorporated herein by reference in their
entireties.
* * * * *