U.S. patent application number 11/739342 was filed with the patent office on 2008-02-07 for method for performing a procedure according to a biometric image.
This patent application is currently assigned to PHILADELPHIA RETINA ENDOWMENT FUND. Invention is credited to Michael A. DellaVecchia, Larry Donoso.
Application Number | 20080033301 11/739342 |
Document ID | / |
Family ID | 39030130 |
Filed Date | 2008-02-07 |
United States Patent
Application |
20080033301 |
Kind Code |
A1 |
DellaVecchia; Michael A. ;
et al. |
February 7, 2008 |
Method for performing a procedure according to a biometric
image
Abstract
A method for performing a procedure on a patient, includes
obtaining a biometric image representative of the patient and
performing the procedure on the patient in accordance with the
biometric image. The patient has an iris and the biometric image
comprises an iris biometric image and the procedure comprises a
medical procedure. First and second iris biometric images; are
obtained and the first and second iris biometric images are
compared to provide a biometric comparison result. A patient is
identified in accordance with the biometric comparison result. The
patient has at least one feature and the feature is represented
within at least one of the first and second iris biometric
images.
Inventors: |
DellaVecchia; Michael A.;
(Berwyn, PA) ; Donoso; Larry; (Philadelphia,
PA) |
Correspondence
Address: |
CAESAR, RIVISE, BERNSTEIN,;COHEN & POKOTILOW, LTD.
11TH FLOOR, SEVEN PENN CENTER
1635 MARKET STREET
PHILADELPHIA
PA
19103-2212
US
|
Assignee: |
PHILADELPHIA RETINA ENDOWMENT
FUND
Philadelphia
PA
|
Family ID: |
39030130 |
Appl. No.: |
11/739342 |
Filed: |
April 24, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10696046 |
Oct 29, 2003 |
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11739342 |
Apr 24, 2007 |
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10011187 |
Nov 13, 2001 |
6648473 |
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10696046 |
Oct 29, 2003 |
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Current U.S.
Class: |
600/477 ;
128/898 |
Current CPC
Class: |
A61F 9/00821 20130101;
A61B 3/14 20130101; A61B 5/117 20130101; A61B 3/12 20130101 |
Class at
Publication: |
600/477 ;
128/898 |
International
Class: |
A61B 3/14 20060101
A61B003/14 |
Claims
1-24. (canceled)
25. A method for performing a procedure on a patient, comprising:
(a) obtaining a biometric image representative of said patient; and
(b) performing said procedure on said patient in accordance with
said biometric image.
26. The method for performing a procedure on an patient of claim
25, wherein said patient has an iris and said biometric image
comprises an iris biometric image.
27. The method for performing a procedure on an patient of claim
26, wherein said procedure comprises a medical procedure.
28. The method for performing a procedure on an patient of claim
26, further comprising: (a) obtaining first and second iris
biometric images; and (b) comparing said first and second iris
biometric images to provide a biometric comparison result.
29. The method for performing a procedure on an patient of claim
28, further comprising identifying a patient in accordance with
said biometric comparison result.
30. The method for performing a procedure on an patient of claim
28, wherein said patient has at least one feature and said feature
is represented within at least one of said first and second iris
biometric images.
31. The method for performing a procedure on an patient of claim
30, further comprising identifying an iris in accordance with said
at least one feature.
32. The method for performing a procedure on an patient of claim
31, further comprising performing a medical procedure in accordance
with said identifying.
33. The method for performing a procedure on an patient of claim
30, further comprising determining a location of said iris in
accordance with said at least one feature.
34. The method for performing a procedure on an patient of claim
30, further comprising determining an orientation of said iris in
accordance with said at least one feature.
35. The method for performing a procedure on an patient of claim
30, further comprising altering a relative location of said iris in
accordance with said at least one feature.
36. The method for performing a procedure on an patient of claim
26, further comprising performing a surgical procedure in
accordance with said biometric image.
37. The method for performing a procedure on an patient of claim
26, further comprising performing a medical diagnosis on said
patient in accordance with said biometric image.
38. The method for performing a procedure on an patient of claim
27, further comprising translating said patient within a coordinate
system in accordance with said biometric image.
39. The method for performing a procedure on an patient of claim
27, further comprising performing said medical procedure upon an
eye of said patient in accordance with said biometric image.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of Invention
[0002] This invention relates to a method and a system for
high-resolution retinal imaging, eye aberration compensation, and
diagnostics based on adaptive optics with direct optimization of an
image quality metric using a stochastic parallel perturbative
gradient descent technique.
[0003] Adaptive optics is a promising technique for both
diagnostics of optical aberrations of the eye and substantially
aberration-free high-resolution imaging of the retina. In existing
adaptive optics techniques adaptive correction is based on
illumination of the retina by a collimated laser beam to create a
small size laser location on the retina surface with consequent
measurement of phase aberrations of the wave scattered by the
retina tissue. Correction of eye optical aberrations is then
performed using the conventional phase conjugation technique.
[0004] This traditional approach has several important drawbacks.
One important drawback is the danger due to an invasive use of the
laser beam focused onto the retina. Other drawbacks include overall
system complexity and the high cost of the necessary adaptive
optics elements such as a wavefront sensor and wavefront
reconstruction hardware. More importantly, due to aberrations the
laser beam location size on the retina is not small enough to use
it as a reference point-type light source and hence conjugation of
the measured wavefront does not result in optimal optical
aberration correction. Additionally, the traditional approach can
produce a turbid image that can make performing an operation with a
microscope difficult.
[0005] One prior art method using a laser is taught in U.S. Pat.
No. 6,095,651 entitled "Method and Apparatus for Improving Vision
and the Resolution of Retinal Images", issued to Williams, et al.
on Aug. 1, 2000. In Williams, et al. teaches a method and apparatus
for improving resolution of retinal images. In this method, a point
source of light is produced on the retina by a laser beam. The
source is reflected from the retina and received at a lenslet array
of a Hartman-Shack wavefront sensor. Thus, higher order aberrations
of the eye can be measured and data can be obtained for
compensating the aberrations using a system including a laser. U.S.
Pat. Nos. 5,777,719 and 5,949,521 provide essentially the same
teachings. While these references teach satisfactory methods for
compensating aberrations, there is some small risk of damaging the
retina since these methods require applying laser beams to the
retina.
[0006] U.S. Pat. No. 5,912,731, entitled "Hartmann-type Optical
Wavefront Sensor" issued to DeLong, et al. on Jun. 5, 1999 teaches
an adaptive optics system using adjustable optical elements to
compensate for aberrations in an optical beam. The aberrations may
be caused, for example, by propagation of the beam through the
atmosphere. The aberrated beam can be reflected from a deformable
mirror having many small elements, each having an associated
separate actuator.
[0007] Part of the reflected beam taught by DeLong can be split off
and directed to impinge on a sensor array which provides
measurements indicative of the wavefront distortion in the
reflected beam. The wavefront distortion measurements can then be
fed back to the deformable mirror to provide continuous corrections
by appropriately moving the mirror elements. Configurations such as
this, wherein the array of small lenses as referred to as a lenslet
array, can be referred to as Shack-Hartmann wavefront sensors.
[0008] Additionally, DeLong teaches a wavefront sensor for use in
measuring local phase tilt in two dimensions over an optical beam
cross section, using only one lenslet arrangement and one camera
sensor array. The measurements of DeLong are made with respect to
first and second orthogonal sets of grid lines intersecting at
points of interest corresponding to positions of optical device
actuators. While this method does teach the way to correct
aberrations in a non-laser light system, it cannot be used in cases
where lasers are required.
[0009] U.S. Pat. No. 6,007,204 issued to Fahrenkrug, et al.
entitled "Compact Ocular Measuring System", issued on Dec. 28,
1999, teaches a method for determining refractive aberrations of
the eye. In the system taught by Fahrenkrug, et al. a beam of light
is focused at the back of the eye of the patient so that a return
light path from the eye impinges upon a sensor having a light
detecting surface. A micro optics array is disposed between the
sensor and the eye along the light path. The lenslets of the micro
optics array focus incremental portions of the outgoing wavefront
onto the light detecting surface so that the deviations and the
positions of the focused portions can be measured. A pair of
conjugate lenses having differing focal lengths is also disposed
along the light path between the eye and the micro optics
array.
[0010] U.S. Pat. No. 6,019,472, issued to Koester, et al. entitled
"Contact Lens Element For Examination or Treatment of Ocular
Tissues" issued on Feb. 1, 2000 teaches a multi-layered contact
lens element including a plurality of lens elements wherein a first
lens element has a recess capable of holding a volume of liquid
against a cornea of the eye. A microscope is connected to the
contact lens element to assist in the examination or treatment of
ocular tissues.
[0011] U.S. Pat. No. 6,086,204, issued to Magnante entitled
"Methods and Devices To Design and Fabricate Surfaces on Contact
Lenses and On Corneal Tissue That Correct the Eyes Optical
Aberrations" on Jul. 11, 2000. Magnante teaches a method for
measuring the optical aberrations of an eye either with or without
a contact lens in place on the cornea. A mathematical analysis is
performed on the optical aberrations of the eye to design a
modified shape for the original contact lens or cornea that will
correct the optical aberrations. An aberration correcting surface
is fabricated on the contact lens by a process that includes laser
ablation and thermal molding. The source of light can be coherent
or incoherent.
[0012] U.S. Pat. No. 6,143,011, issued to Hood, et al. entitled
"Hydrokeratome For Refractive Surgery" issued on Nov. 7, 2000
teaches a high speed liquid jet for forming an ophthalmic
incisions. The Hood, et al. system is adapted for high precision
positioning of the jet carrier. An airway beam may be provided by a
collimated LED or laser diode. The laser beam can be used to align
the system.
[0013] U.S. Pat. No. 6,155,684, issued to Billie, et al. entitled
"Method and Apparatus for Precompensating The Refractive Properties
of the Human Eye With Adaptive Optical Feedback Control" issued on
Dec. 5, 2000. Billie, et al. teaches a system for directing a beam
of light through the eye and reflecting the light from the retina.
A lenslet array is used to obtain a digitized acuity map from the
reflected light for generating a signal that programs an active
mirror. In accordance with the signal the optical paths of
individuals beams in and the beam of light are made to appear to be
substantially equal to each other. Thus, the incoming beam can be
precompensated to allow for the refractive aberrations of the eyes
that are evidenced by the acuity map.
[0014] Additional methods for using adaptive optics to compensate
for aberrations of the human eye are taught in J. Liang, D.
Williams and D. Miller, "Supernormal Vision and High-Resolution
Retinal Imaging Through Adaptive Optics," J. Opt. Soc. Am. A, Vol.
14, No. 11, pp. 2884-2891, 1997 and F. Vargas-Martin, P. Prieto,
and P. Artal, "Correction of the Aberrations in the Human Eye with
a Liquid-Crystal Spatial Light Modulator: Limits to Performance,"
J. Opt. Soc. Am. A, Vol. 15, No. 9, pp. 2552-2561, 1998.
Additionally, J. Liang, B. Grimm, S. Goelz, and J. Bille,
"Objective Measurement of Wave Aberrations of the Human Eye with
the Use of a Hartmann-Shack Wave-Front Sensor," J. Opt. Soc. Am. A,
Vol. 11, No. 7, pp. 1949-1957, 1994 teaches such a use of adaptive
optics.
[0015] Furthermore, it is known in the art to use a PSPGD
optimization algorithm in different applications. For example, see
M. Vorontsov, and V. Sivokon, "Stochastic Parallel-Gradient-Descent
Technique for High-Resolution Wave-Front Phase-Distortion
Correction," J. Opt. Soc. Am. A, Vol. 15, No. 10, pp. 2745-2758,
1998. Also see M. Vorontsov, G. Carhart, and J. Ricklin, "Adaptive
Phase-Distortion Correction Based on Parallel Gradient-Descent
Optimization," Optics Letters, Vol. 22, No. 12, pp. 907-909,
1997.
[0016] It is well known in the art to scan an iris and obtain an
iris biometric image. See, for example, U.S. Pat. Nos. 4,641,349,
5,291,560, 5,359,669, 5,719,950, 6,289,113, 6,377,699, 6,526,160,
6,532,298, 6,539,100, 6,542,624, 6,546,121, 6,549,118, 6,556,699,
6,594,377, 6,614,919, and U.S. Patent Application Nos.
20010026632A1, 20020080256A1, 20030095689A1, 20030120934A1,
20020057438A1, 20020132663A1, 20030018522A1, 20020158750A1.
However, such images were often not optimal and their applicability
was somewhat limited.
[0017] 2. Description of Related Art
[0018] All references cited herein are incorporated herein by
reference in their entireties.
BRIEF SUMMARY OF THE INVENTION
[0019] The invention includes a method for clarifying an
optical/digital image of an object to perform a procedure on an
object having the steps of applying to the object a light beam
formed of incoherent light and reflecting the applied incoherent
light beam from the object to provide a reflected light beam and
providing electrical signals representative of the reflected light
beam. An image quality metric is determined in accordance with the
electrical signals and an image is determined in accordance with
the image quality metric. The procedure is performed in accordance
with the image quality metric.
[0020] In a further method of the invention a procedure is
performed on an eye having an iris. An iris biometric image
representative of the iris is obtained and the procedure is
performed on an eye in accordance with the iris biometric
image.
[0021] Additionally a method for optimizing electromagnetic energy
in a system for processing an image of an object in order to
perform a procedure on an object is provided. The method includes
applying to the object a plurality of light beams formed of
incoherent light at a plurality of differing frequencies and
reflecting the plurality of applied incoherent light beams from the
object to provide a plurality of reflected light beams. The method
also includes providing a corresponding plurality of electrical
signals representative of the reflected light beams of the
plurality of reflected light beams and determining a corresponding
plurality of image quality metrics in accordance with the plurality
of electrical signals. A corresponding plurality of images is
determined in accordance with the plurality of image quality
metrics and an image of the plurality of images is selected in
accordance with a predetermined image criterion to provide a
selected image. The method also includes determining a frequency of
the plurality of differing frequencies in accordance with the
selected image to provide a determined frequency and performing the
procedure on an object in accordance with the determined
frequency.
[0022] The inventions also deals with new methods of
high-resolution imaging and construction of images of the retina,
and adaptive correction and diagnostics of eye optical aberrations,
as well as such imaging of articles of manufacture, identifying
articles and controlling a manufacturing process. Additionally, the
method is applicable to identifying individuals in accordance with
such images for medical purposes and for security purposes, such as
a verification of an identity of an individual. These applications
can be performed using adaptive optics techniques based on parallel
stochastic perturbative gradient descent (PSPGD) optimization. This
method of optimization is also known as simultaneous perturbation
stochastic approximation (SPSA) optimization. Compensation of
optical aberrations of the eye and improvement of retina image
resolution can be accomplished using an electronically controlled
phase spatial light modulator (SLM) as a wavefront aberration
correction interfaced with an imaging sensor and a feedback
controller that implements the PSPGD control algorithm.
[0023] Examples of the electronically-controlled phase SLMs include
a pixelized liquid-crystal device, micro mechanical mirror array,
and deformable, piston or tip-tilt mirrors. Wavefront sensing can
be performed at the SLM and the wavefront aberration compensation
is performed using retina image data obtained with an imaging
camera (CCD, CMOS etc.) or with a specially designed very large
scale integration imaging chip (VLSI imager). The retina imaging
data are processed to obtain a signal characterizing the quality of
the retinal image (image quality metric) used to control the
wavefront correction and compensate the eye aberrations.
[0024] The image quality computation can be performed externally
using an imaging sensor connected with a computer or internally
directly on an imaging chip. The image quality metric signal is
used as an input signal for the feedback controller. The controller
computes control voltages applied to the wavefront aberration
correction. The controller can be implemented as a computer module,
a field programmable gate array (FPGA) or a VLSI micro-electronic
system performing computations required for optimization of image
quality metrics based on the PSPGD algorithm.
[0025] The use of the PSPGD optimization technique for adaptive
compensation of eye aberration provides considerable performance
improvement if compared with the existing techniques for retina
imaging and eye aberration compensation and diagnostics, and
therapeutic applications. The first advantage is that the PSPGD
algorithm does not require the use of laser illumination of the
retina and consequently significantly reduces the risk of retina
damage caused by a focused coherent laser beam. A further advantage
is that the PSPGD algorithm does not require the use of a wavefront
sensor or wavefront aberration reconstruction computation. This
makes the entire system low-cost and compact if compared with the
existing adaptive optics systems for retina imaging. Additionally,
the PSPGD algorithm can be implemented using a parallel analog,
mix-mode analog-digital or parallel digital controller because of
its parallel nature. This significantly speeds up the operations of
the PSPGD algorithm, providing continuous retina image improvement,
eye aberration compensation and diagnostics.
[0026] Thus, in the adaptive correction technique of the present
invention neither laser illumination nor wavefront sensing are
required. Optical aberration correction is based on direct
optimization of the quality of an retina image obtained using a
white light, incoherent, partially coherent imaging system. The
novel imaging system includes a multi-electrode phase spatial light
modulator, or an adaptive mirror controlled with a computer or with
a specially designed FPGA or VLSI system. The calculated image
quality metric is optimized using a parallel stochastic gradient
descent algorithm. The adaptive optical system is used in order to
compensate severe optical aberrations of the eye and thus provide a
high-resolution image and/or of the retina tissue and the eye
aberration diagnostic.
BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS
[0027] The invention will be described in conjunction with the
following drawings in which like reference numerals designate like
elements and wherein:
[0028] FIGS. 1A,B show a schematic representation of system
suitable for practicing the eye aberration correcting method of the
present invention.
[0029] FIG. 2 shows a flow chart representation of control
algorithm suitable for use in the system of FIG. 1 when practicing
the method of the present invention.
[0030] FIGS. 3A,B show images of an artificial retina before and
after correction of an aberration
[0031] FIGS. 4A,B show an eye and a biometric image of the iris of
the eye.
[0032] FIG. 5 shows a block diagram representation of an iris
biometric image comparison system which can be used with the
aberration correcting system of FIG. 1.
[0033] FIG. 6 shows a block diagram representation of an iris
positioning system which can be used in cooperation with the
aberration correcting system of FIG. 1.
[0034] FIG. 7 shows an illumination frequency optimization system
which can be used in cooperation with the aberration correcting
system of FIG. 1.
[0035] FIG. 8 shows an image superpositioning system which can be
used with the aberration correcting system of FIG. 1.
DETAILED DESCRIPTION OF THE INVENTION
[0036] Referring now to FIGS. 1A,B there are shown schematic
representations of the aberration correcting system 10 of the
present invention. In the aberration correcting system 10 a light
beam from a white light source 1 is redirected by a mirror 2 in
order to cause it to enter an eye. In accordance with the present
invention the white light beam from the light source 1 can be any
kind of incoherent light.
[0037] The light from the mirror 2 reaches the retina 4 of the eye
and reflected light exits the eye to provide two light beams, one
passing in each direction, as indicated by arrow 3. The exiting
light beam then passes through an SLM 5. The light beam from the
SLM 5 enters an image sensor 6. The image sensor 6 can be a charge
coupled capacitor device or any other device capable of sensing and
digitizing the light beam from the SLM 5.
[0038] The imaging sensor 6 can include an imaging chip for
performing the calculations required to determine an image quality
metric. The image quality metric can thus be computed on the
imaging chip directly or it can be calculated using a separate
computational device/computer 7 that calculates the image quality
metric of the retina image. It is the use of a digitized image in
this manner that permits the use of an incoherent light rather than
a coherent light for performing the operations of the aberration
correction correcting system 10.
[0039] The computational device 7 sends a measurement signal
representative of the image quality metric to a controller 8. The
controller 8 implements a PSPGD algorithm by computing control
voltages and applying the computed control voltages to the SLM 5.
The PSPGD algorithm used by the controller 8 can be any
conventional PSPGD algorithm known to those of ordinary skill in
the art. In the preferred embodiment of the invention, the
controller 8 continuously receives digital information about the
quality of the image and continuously updates the control voltages
applied to the SLM 5 until the quality of the retina image is
optimized according to predetermined image quality optimization
criteria.
[0040] Referring now to FIGS. 2 and 3A,B there are shown a flow
chart representation of a portion of a PSPGD control algorithm 20
for use in cooperation with the aberration correcting system 10 in
order to practice the present invention as well as representations
of the corrected image, both before correction (3A) and after
correction (3B). In order to simplify the drawing a single
iterative step of the PSPGD control algorithm 20 is shown with a
loop for repeating the single iterative step until the quality of
the compensation is acceptable.
[0041] In step 25 of the PSPGD control algorithm 20 a measurement
and calculation of the image quality metric is performed. This step
includes the retinal image capture performed by the sensor 5 and
the calculation of the image quality metric performed by the
computational device 7 within the aberration correcting system 10.
The image captured by the sensor 5 at the beginning of the
operation of the PSPGD control algorithm 20 can be substantially as
shown in FIG. 3A, as previously described. One can use any relevant
metric entity as an image quality metric. For example, in one
embodiment of the PSPGD control algorithm 20 the image quality
metric can be a sharpness function. A sharpness function suitable
for use in the present invention can be defined as
J=.intg.|.gradient..sup.2I(x,y)|dxdy where I(x,y) is the intensity
distribution in the image, and .gradient..sup.2 is the Laplacian
operator over the image. The Laplacian can be calculated by
convolving the image with a Laplacian kernel. The convolving of the
image can be performed by a special purpose VLSI microchip.
Alternately, the convolving of the image can be performed using a
computer that receives an image from a digital camera as described
in more detail below. In another embodiment different digital
high-pass filters can be used rather than the Laplacian
operator.
[0042] Additionally, a frequency distribution function can be used
rather than a sharpness function when determining the image quality
metric. The use of a frequency distribution function allows the
system to distinguish tissues of different colors. This is useful
where different kinds of tissue, for example, different tumors,
have different colors. Locating tumors in this manner also permits
the invention to provide tumor location information, such as a grid
location on a grid having a pre-determined reference in order to
assist in diagnosis and surgery. It also permits the invention to
provide tumor size and type information. Additionally, the use of a
frequency distribution function permits a surgeon to determine
which light frequencies are best for performing diagnosis and
surgery.
[0043] The image quality metric J can also be calculated either
optically or digitally using the expression introduced in:
J=.intg.|F{exp [i.gamma.I(x,y)]}|.sup.4dxdy
[0044] Where F is the Fourier transform operator and [[a]] .gamma.
is a parameter that is dependent upon the dynamic range of the used
image.
[0045] In step 30 of the PSPGD control algorithm 20 random
perturbations in the voltages applied to the SLM 5 electrodes are
generated. The SLM 5 can be a liquid crystal membrane for modifying
the light beam according to the electrical signals from controller
8 in a manner well understood by those skilled in the art.
[0046] In order to generate the perturbations for application to
the electrodes for the SLM 5 random numbers with any statistical
properties can be used as perturbations. For example, uncorrelated
random coin flip perturbations having identical amplitudes|u.sub.j
and the Bernoulli probability distribution: du.sub.j=.+-.p,
Pr(du.sub.j=+p)=0.5 for all j=1, . . . , N (N=the number of control
channels) and iteration numbers can be used. Note that
Non-Bernoulli perturbations are also allowed in the PSPGD control
algorithm 20.
[0047] In step 35 of the PSPGD control algorithm 20 a measurement
of the perturbed image quality metric and a computation of the
image quality perturbation .delta.J.sup.(m) are performed.
Following the determination of the perturbed image quality metric,
the gradient estimations {tilde over
(J)}'.sub.j.sup.(m)=.delta.J.sup.(m).pi..sub.j.sup.(m) are computed
as shown in step 40.
[0048] The updated control voltages are then determined as shown in
step 45. Therefore, a calculation of:
u.sub.j.sup.(m+1)=.sub.j.sup.(m)-.gamma..delta.J.sup.(m).pi..sub.j.sup.(m-
) is performed.
[0049] To further improve the accuracy of gradient estimation in
the PSPGD control algorithm 20 a two-sided perturbation can be
used. In a two-sided perturbation two measurements of the cost
function perturbations J.sup.+ and J.sup.- are taken. The two
measurements correspond to sequentially applied differential
perturbations +u.sub.j/2 and -u.sub.j/2.
[0050] It follows that: dJ=dJ.sup.30-dJ.sup.- and {tilde over
(J)}'.sub.j=.delta.J.delta.u.sub.j which can produce a more
accurate gradient estimate.
[0051] The process steps 25-45 of the PSPGD control algorithm 20
are repeated interactively until the image quality metric has
reached an acceptable level as determined in step 50. The choice of
an acceptable level of the image quality metric is a conventional
one well known to those skilled in the art. As shown in step 55 the
aberration is then corrected and an image of the retina can be
taken. The image resulting from the operation of the PSPGD
algorithm 20 can be as shown in FIG. 3B.
[0052] The eye aberration function (x,y) can be calculated from
known voltages applied to wavefront correction {u.sub.j} at the end
of the iterative optimization process and known response functions
of {S.sub.j(x,y)} wavefront correction. j .function. ( x , y ) = j
= 1 N .times. u j .times. S j .function. ( x , y ) ##EQU1##
[0053] Referring now to FIGS. 4A,B, there is shown an eye 80 having
an iris 84 with a pupil 88 therein and an iris biometric image 90.
The iris biometric image 90 is a biometric image of the iris 84,
which can be obtained using an iris scanning system, such as the
aberration correcting system 10. In an alternate embodiment of the
invention, the iris biometric image 90 can be obtained by any other
system (not shown) capable of scanning and digitizing an iris and
providing an image that is characteristic of the iris, such as a
bar code type output as shown in FIG. 4B. Furthermore, it will be
understood that every human eye has an unique iris biometric image
when it is scanned and digitized in this manner. Thus, an iris
biometric image can be used as a unique identifier of an individual
in the manner that fingerprints are used or even to distinguish
between the left and right eyes of an individual.
[0054] When the predetermined image quality is obtained, a
plurality of locations 92 within the iris 84 can be defined. In one
preferred embodiment of the invention, four locations 92 can be
selected. The four locations 92 can be disposed on the corners of a
rectangle which is concentric with the iris 84. The locations 92
can thus be easily used to find the center of the iris 84. The four
locations 92 are represented on the iris biometric image 90 in
accordance with the mathematical relationships previously
described. Thus, the xy coordinates of the locations 92 may be
mapped into corresponding xy coordinates within the iris biometric
image 90 if a spatial transform such as the sharpness function is
used, while they may be convolved over areas of the iris biometric
image 90 if a frequency or other transform is used.
[0055] Various features already occurring in the eye 80 also have
corresponding representations within the iris biometric image 90.
The location and study of such features can be used to diagnose
pathologies, for example, to diagnose tumors and to determine the
position of the eye iris 84. As a further example, a feature can be
studied several times over a period of time to determine how its
parameters are is changing.
[0056] Referring now to FIG. 5, there is shown the iris biometric
image comparison system 100. The iris biometric image comparison
system 100 receives the previously determined iris biometric image
90 as one of its inputs. Additionally, a new iris biometric image
95 is produced, for example, before or during the performance of a
procedure on the eye 80. The new iris biometric image 95 is
received by the image comparison system 100 as a second input. The
new iris biometric image 95 can be provided by the aberration
correction system 10. The light beam used to obtain the iris
biometric image 95 can be the same light beam being used for other
purposes during the procedure.
[0057] When using the aberration correcting system 10, the image
can be optimized by executing additional iterations of the PSPGD
control algorithm 20. The algorithm can be iterated until a
predetermined image quality is obtained and computing the image
quality metric within the computer 7 as previously described. In
addition to performing more iterations of the PSPGD control
algorithm 20, increased image sensitivity quality can be obtained
by increasing the number of pixels in the digitized image or
increase image sensitivity can be obtained by increasing the number
of measuring points in the iris 84.
[0058] When performing the method of the image comparison system
100 the iris biometric image 90 can be assumed by the image
comparison system 100 to be the correct iris biometric image of the
iris 84 upon which the procedure is to be performed. Furthermore,
it can be assumed that the iris biometric image 90 applied to the
image comparison system 100 was obtained when the position and
orientation of the eye 80 were correct.
[0059] The iris biometric images 90, 95 are compared by the image
comparison system 100 at decision 104. A determination is made as
to whether the iris biometric image 95 is an image of the same iris
84 that was imaged to produce the enrolled iris biometric image 90.
Any of the well known correlation techniques can be used for the
comparison. Substantially similar correlation techniques can be
used for the comparison if the locations 92 are used or if other
markings within the iris 84 are used. The sensitivity of the
comparison can be adjusted by those skilled in the art.
[0060] If the determination of decision 104 is negative, then the
procedure being performed on the eye 80 is not continued as shown
in block 102. If the determination of decision 104 is positive,
then a determination can be made in decision 106 whether the iris
84 is positioned in the xy directions correctly and oriented or
rotated correctly at the time that the iris biometric image 95 was
produced. The determination of decision 106 can be used for a
number of purposed. For example, it could be used to direct a beam
of light to a predetermined location within the eye 80. Thus, if
the determination of decision 106 is negative, the beam can be
redirected as shown in block 110. The position of the iris 84 can
be checked again in decision 106. When the position of the iris 84
is correct, the procedure can begin, as shown in block 112.
[0061] The determination of decision 106 can be made in accordance
with the representations of locations 92 within the iris 84
selected when iris biometric image 90 was obtained. If
corresponding locations are found in the iris biometric image 95 in
the same positions, the determination of decision 106 is positive.
Alternately, the determination of decision 106 can be made in
accordance with predetermined features or markings within the iris
84 other than the locations 92. The method of the image comparison
system 100 can be used to determine whether the iris 84 is rotated
or translated in the direction of either of the axes orthogonal to
the arrow 3 shown in FIGS. 1A,B.
[0062] Referring now to FIG. 6, there is shown the iris positioning
system 120. The iris positioning system 120 is adapted to precisely
position the iris 84 while performing a procedure on the eye 80.
The iris positioning system 120 differs from the iris biometric
image comparison system 100 primarily in the fact that the iris
positioning system 120 is provided with a servo 124. The servo 124
is effective in modifying the relative positions of the iris 84 and
the camera 6 of the aberration correcting system 10 which can be
coupled to equipment (not shown) used to perform the procedure in
the eye.
[0063] In the iris positioning system 120 a determination is made
in decision 104 whether the iris biometric images 90, 95 were made
on the same eye as previously described with respect to image
comparison system 100. The procedure is continued only if a
positive determination is made. A determination is then made in
decision 106 whether the iris 84 is in the correct position. The
determination of decision 106 can be made by comparing the iris
biometric images 90, 95 in accordance with the locations 92 or any
other markings within the iris 84 as previously described. The
determination made can be, for example, whether the iris 84 is
rotated or translated in the x or y direction at the time that the
iris biometric image 95 is obtained.
[0064] When a determination is made that the iris 84 is in an
incorrect position, a correction signal representative of the error
is calculated. The error correction signal is applied to the servo
124. The servo 124 is adapted to receive the error correction
signal resulting from the determinations of decision 106 and to
adjust the relative positions of the iris 84 and the equipment
performing the procedure in accordance with the signal in a manner
well understood by those skilled in the art. Servos 124 capable of
applying both rotational and multi-axis translational corrections
are both provided in the preferred embodiment of the invention.
Either the object such as the iris 84 or the equipment can be moved
in response to the determination of decision 106.
[0065] The method of the iris positioning system 120 can be
repeatedly performed, or constantly performed, during the
performance of a procedure on the eye 80 to re-capture, re-evaluate
or refine the process the eye 80. Thus, the relative positions of
the iris 84 and the procedure equipment can be kept correct at all
times.
[0066] Referring now to FIG. 7, there is shown the illumination
frequency optimization system 130. The illumination frequency
optimization system 130 is an alternate embodiment of the
aberration correcting system 10. Within the frequency optimization
system 130 a variable frequency light source 132 rather than a
single frequency light source applies a light beam to the eye 80.
The variable frequency light source 132 can be a tunable laser, a
diode, filters in front of a light source, a diffraction grating or
any other source of a plurality of frequencies of light. An image
quality metric can be obtained and optimized in the manner
previously described with respect to system 10.
[0067] Using the variable frequency light source 132, it is
possible to conveniently adjust the frequency of the light beam
used to illuminate the eye 80 or object 80 at a plurality of
differing frequencies and to obtain a plurality of corresponding
image quality metrics. In order to do this, the frequency of the
light applied to the eye 80 by the variable frequency light source
132 can be repeatedly adjusted and a new image quality metric can
be obtained at each frequency. Each image quality metric obtained
in this manner can be optimized to a predetermined level. The
levels of optimization can be equal or they can differ. While the
optimizations should be done using the frequency distribution, it
is possible to return to images optimized using the frequency
distribution and sharpen using the sharpness function.
[0068] It is well understood that differing types of tissue can be
visualized best with differing frequencies of light. For example,
tumors, lesions, blood and various tissues as well as tissues of
varying pathologies can be optimally visualized at different
frequencies since their absorption and reflection properties vary.
Thus, by adjusting the frequency applied to the eye 80 by the
variable frequency light source 132 and viewing the results, the
best light for visualizing selected features can be determined.
Furthermore, using this method there can be several optimized
images for one eye. For example, there can be different optimized
images, for a tumor, for a lesion and for blood. The determination
of the best frequency for each image can be a subjective judgment
made by a skilled practitioner.
[0069] A skilled practitioner can use the illumination frequency
optimization system 130 to emphasize and de-emphasize selected
features within images of the eye 80. For example, when obtaining
an iris biometric image 95, the iris 84 may be clouded due to
inflammation of the eye 80 or the presence of blood in the eye 80.
It is possible to effectively remove the effects of the
inflammation blood with the assistance of the frequency
optimization system 130 by varying the frequency of the light
provided by the light source 132 until the optimum frequency is
found for de-emphasizing the inflammation or blood and permitting
the obscured features to be seen. In general, it is often possible
to visualize features when another feature is superimposed on them
by removing the superimposed feature using system 130.
[0070] In order to remove the effects of the inflammation or blood,
a plurality of images of the eye 80 can be provided and the
frequency at which the blood or inflammation is least apparent can
be determined. Removing these features from the iris biometric
image 95 can facilitate its comparison with the iris biometric
image 90. Furthermore, when the biometric image 95 is obtained from
the iris 110 of a person wearing sunglasses, it is possible to
remove the effects of the sunglasses in the same manner and
identify an eye 80 behind the sunglasses. This feature is useful
when identifying people outside of laboratory conditions.
[0071] Referring now to FIG. 8, there is shown the image
superposition system 150. In many cases it is desirable to perform
a procedure on an eye 80 when selected features of the eye 80 are
obscured by other features, where different features are visualized
best at different frequencies, or where the criteria for
emphasizing and de-emphasizing features can change during a
procedure. Image superposition 100 can be used to obtain improved
feature visualization under these and other circumstances.
[0072] For example, white light is often preferred for illuminating
an iris 84 because in many cases white light shows the most
features. However, if white light is used to illuminate an iris 84
when the iris 84 is clouded with blood, the blood can block the
white light. This can make it difficult, or even impossible, to
visualize the features that are obscured by the blood. One solution
to this problem is to use red light to illuminate the iris 84 and
visualizes the features obscured by the blood.
[0073] However, the red light could fail to optimally visualize the
features which are normally visualized best using, for example,
white light. The image superposition system 150 can solve this
problem by superimposing two images such as the direct image 166
and the projected image 170, where the images 166, 170 are obtained
using light sources of differing frequencies. The optimum
frequencies for obtaining each of the images 166, 170 can be
determined using the illumination frequency optimization system
130.
[0074] For example, an object 168 to be visualized can be
illuminated with incoherent white light to provide the direct image
166. Illumination of the object 168 by white light to produce the
direct image 166 can be provided using any of the known methods for
providing such illumination of objects to provide digital images.
The direct image 166 can be sensed and digitized using an image
sensor 152 which senses light traveling from the object 168 in the
direction indicated by the arrows 156, 164.
[0075] The image sensor 152 senses the direct image 166 of the
object 168 by way of a superposition screen 160. The superposition
screen 160 can be formed of any material capable of transmitting a
portion to the light applied to it from the object 168 to the image
sensor 152, and reflecting a portion of the same light. For
example, the superposition screen 168 can be formed of glass or
plastic. A viewer, a TV screen or a gradient filter can also serve
as the superposition screen 160. The screen 160 can also be a
gradient filter. In a preferred embodiment of the invention, the
angle 172 of the superposition screen 160 can be adjusted to
control the amount of light it transmits and the amount it
reflects.
[0076] The projected image 170 of the object 168 can be obtained
using, for example, the aberration correcting system 10 as
previously described. Illumination with red light or any other
frequency of light can be used within the aberration correcting
system 10 to obtain the superposition image 178. The superposition
image 178 is applied to an image projector 176 by the aberration
correcting system 10. The image projector 176 transmits the
projected image 170 in accordance with the superposition image 178
in the direction indicated by the arrow 174 and applies it to the
superposition screen 160.
[0077] A portion of the projected image 170 applied to the
superposition screen 160 by the projector 176 is reflected off of
the superposition screen 160 and applied to the image sensor 152 in
the direction indicated by the arrow 156. The amount of the
projected image 170 reflected to the image sensor 152 can be
adjusted by adjusting the angle 172 of the superposition screen
160. The image projector 176 is disposed in a location adapted to
apply the projected image 170 to the superposition screen 160 in
the same region of the superposition screen 160 where the direct
image 166 is applied. When the images 166, 170 are applied to the
superposition screen 160 in this manner, they are superimposed and
the image sensed by the image sensor 152 is thus the superposition
or composite of the images 166, 170.
[0078] Adjustment of the angle 172 results in emphasizing and
de-emphasizing the images 166, 170 relative to each other. This is
useful, for example, where different features visualized
selectively at differing frequencies must be brought in and out of
visualization in the composite image for different purposes.
Another time where this is useful is when the intensity of one of
the images 166, 170 is too high relative to the other and must be
adjusted down or too low and must be adjusted up.
[0079] In various alternate embodiments of the image superposition
system 150, either or both of the images 166,170 can be optimized
using the PSPGD algorithm 20 within the aberration correction
system 10. Furthermore, the images 166, 170 can be optimized to
differing degrees by the PSPGD algorithm 20 and with differing
optimization criteria in order to emphasis one over the other or to
selectively visualize selected features within the images 166,170
and thus, within the composite image sensed by image sensor 152.
This permits selected features of the eye 80 to be brought into
view and brought out of view as convenient at different times
during a diagnosis or a procedure.
[0080] Thus, the illumination used to obtain the images 166, 170
superimposed by the image superposition system 150 does not need to
be red and white light. The illumination used can be light of any
differing frequencies. The frequencies selected for obtaining the
images 166, 170 can be selected in accordance with the sharpness
function on the frequency distribution as previously described.
[0081] The images superimposed by the image superposition system
150 do not need to be obtained by way of a camera, such as the
camera 6 of the aberration correction system 10. A microscope, an
endoscope, or any other type of device having an image sensor
capable of capturing transmission, absorption or reflection
properties of an object or tissue in a normal state or enhancement
by such materials as markers and chromophores and thereby providing
an optical/digital signal that can be applied to the computer 7 for
optimization using the PSPGD algorithm 20 can be used. Thus, for
example, an image obtained from an endoscope or a microscope can be
superimposed upon an image obtained from an camera using the method
of the present invention. Images from endoscopes, microscopes and
other devices can be digitized, and superimposed and synthesized
with each other. It will be understood that images obtained from
such devices and optimized using the PSPGD algorithm 20 can be used
in any other way that images obtained from the PSPGD algorithm 20
using camera 6 are used.
[0082] The description herein will so fully illustrate my invention
that others may, by applying current or future knowledge, adopt the
same for use under various conditions of service. For example, the
invention may be used for ophthalmological procedures such as
photocoagulation, optical biopsies such as measuring tumors
anywhere in the eye, providing therapy, performing surgery,
diagnosis or measurements. Additionally, it can be used for
performing procedures on eyes outside of laboratory or medical
environments. Furthermore, the method of the present invention can
be applied to any other objects capable of being imaged in addition
to eyes and images of an object provided. In accordance with the
method of the invention can be used when performing such procedures
on other objects.
[0083] While the invention has been described in detail and with
reference to specific examples thereof, it will be apparent to one
skilled in the art that various changes and modifications can be
made therein without departing from the spirit and scope
thereof.
* * * * *