Patent EP0223356A2 successfully refreshed from Google Patents.
EP0223356A2
Expired / Lapsed
EP
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Two-dimensional eye fundus scanning apparatus
Assignee: The Schepens Eye Research Institute Inc
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Filing: 1986-09-16
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Granted: —
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Expires: 2006-09-16
Abstract
Abstract An optical instrument which operates with an incident optical beam scanned at high rates and with correspondingly small sized scanning devices, has a double-scanning optical system (15, 17). The output reflected beam that is detected overfills the first-stage scanning element, yet the instrument attains a relatively high-contrast image. The instrument provides for astigmatism correction, graphic generation in the scanned beam, and the use of infrared wavelength laser beams as well as visible wavelength laser beams. It also provides for generating system timing pulses from a rotating scanning element (15).
Inventors
- 👤 Robert H. Webb
- 👤 George W. Hughes
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-26 09:59
CPC Classifications
A; A61; A61B; A61B3/00; A61B3/10; A61B3/1025
Claims Analysis
Total Claims: 54
Claim 1
Independent Claim
340 words
A scanning ophthalmoscope for providing a two-dimensional output representation of reflection characteristics of the eye fundus, said apparatus comprising, a laser source (11) for generating a laser beam of defined cross sectional area which is small compared to an area of the fundus (19 a ) which is to be scanned and to the pupil of the eye, an optical system for directing said laser beam through the pupil of the eye onto said fundus area, said optical system incl uding, a first scanning element comprising a rotatable element (15) having spaced facets for changing the direction of an incident laser beam and driving means for rotating said reflector to scan said laser beam along a first coordinate across an area of said fundus (19 a ), reflective means (18) for directing said laser beam from said first scanning element through approximately the centre of the eye pupil onto the fundus area, an exit aperture for reflected light from said scanned fundus area, said exit aperture being large compared to the beam cross section dimension, said reflective means being positioned to produce at the facet of said first scanning element a conjugate image of said eye pupil, a detector (21), beam separating means (14) positioned to direct the input laser beam toward said first scanning element, and to direct the reflected light from said scanned fundus area toward said detector (21), said beam separating means including a central stop for said reflected light, said central stop being substantially the same cross sectional size as said input laser beam cross section, said detector means (21) being positioned optically beyond said beam separating means to receive said reflected light from said rotating reflector which passes back along the path toward said beam outside of said stopped central portion, said detector means generating a signal varying in time with the amount of light directed from said first scanning means onto said detector means, and display means (23) for providing said two-dimensional output representation of said eye fundus in reponse to said detector signal.
Claim 2
Dependent Claim
340 words
A scanning ophthalmoscope for providing a two-dimensional output representation of reflection characteristics of the eye fundus, said apparatus comprising, a laser source (11) for generating a laser beam of defined cross sectional area which is small compared to an area of the fundus (19 a ) which is to be scanned and to the pupil of the eye, an optical system for directing said laser beam through the pupil of the eye onto said fundus area, said optical system incl uding, a first scanning element comprising a rotatable element (15) having spaced facets for changing the direction of an incident laser beam and driving means for rotating said reflector to scan said laser beam along a first coordinate across an area of said fundus (19 a ), reflective means (18) for directing said laser beam from said first scanning element through approximately the centre of the eye pupil onto the fundus area, an exit aperture for reflected light from said scanned fundus area, said exit aperture being large compared to the beam cross section dimension, said reflective means being positioned to produce at the facet of said first scanning element a conjugate image of said eye pupil, a detector (21), beam separating means (14) positioned to direct the input laser beam toward said first scanning element, and to direct the reflected light from said scanned fundus area toward said detector (21), said beam separating means including a central stop for said reflected light, said central stop being substantially the same cross sectional size as said input laser beam cross section, said detector means (21) being positioned optically beyond said beam separating means to receive said reflected light from said rotating reflector which passes back along the path toward said beam outside of said stopped central portion, said detector means generating a signal varying in time with the amount of light directed from said first scanning means onto said detector means, and display means (23) for providing said two-dimensional output representation of said eye fundus in reponse to said detector signal.
Claim 3
Dependent Claim
64 words
An ophthalmoscope as claimed in claim 1, characterised in that said first scanning element has a dimension along the coordinate of scan and a path of travel of each facet of said scanning element such that each facet sweeps across substantially the entire cross section of said reflected beam along the coordinate of scan while reflecting light back toward and incident upon said detector.
Claim 4
Dependent Claim
21 words
An ophthalmoscope as claimed in claim 1 or claim 2, characterised in that said reflective means is a focussing mirror (18).
Claim 5
Dependent Claim
53 words
An ophthalmoscope as claimed in any preceding claim, characterised in that the cross sectional area of said eye pupil image conjugate at the surface of the facet of said scanning element is allowed to be large compared to the dimension of the facets of said first scanning element along the coordinate of scan.
Claim 6
Dependent Claim
19 words
An ophthalmoscope as claimed in any preceding claim, characterised in that said first scanning element is a multifaceted polygon.
Claim 7
Dependent Claim
52 words
An ophthalmoscope as claimed in claim 3, characterised in that said focussing mirror (18) is tilted about one axis, the relative position of said focussing mirror along the optical axis being adjusted to compensate for astigmatism produced by the tilt in the pupillary cross section of the envelope of the scanned beam.
Claim 8
Dependent Claim
81 words
An ophthalmoscope as claimed in claim 5, characterised in that the dimension of each polygon facet along the coordinate of scan, the dimension of the beam reflected from said fundus at the surface of said polygon facet, and the path of travel of each facet of said polygon along the coordinate of scan is such that a single facet sweeps across the entire cross sectional area of said beam in the direction of scan while reflecting light back toward said detector.
Claim 9
Dependent Claim
75 words
An ophthalmoscope as claimed in any preceding claim, characterised in that said beam separating means (14) is a turning mirror having a reflecting surface just large enough to encompass the defined cross sectional area of said laser beam, said turning mirror being positioned to intercept said laser beam and redirect it onto said first scanning element, said turning mirror being positioned to act as a central stop for said reflected light passing toward said detector.
Claim 10
Dependent Claim
55 words
An ophthalmoscope as claimed in any preceding claim, characterised in that a second scanning element (17) is arranged in optical alignment between said first scanning element and the eye to be scanned for moving said scanning laser beam in a direction normal to said first coordinate to effect a two-dimensional scan of said fundus area.
Claim 11
Dependent Claim
99 words
An ophthalmoscope as claimed in claim 9 when dependent on claim 3, characterised by a second focussing mirror (16) positioned between said scanning elements (15 and 17) as a conjugate relay for dividing said laser beam reflected from the facet of said first scanning element (15) onto the surface of said second focussing mirror, wherein one of said focussing mirrors is tilted about one axis, the relative positions of said focussing mirrors on the optical axis being adjusted to compensate for the astigmatism produced by said tilt in the pupillary cross section of the envelope of the scanned beam.
Claim 12
Dependent Claim
22 words
An ophthalmoscope as claimed in any preceding claim, characterised in that said laser beam has a wave length in the infrared region.
Claim 13
Dependent Claim
79 words
An ophthalmoscope as claimed in any preceding claim, characterised by a diaphragm stop (26) positioned at the retinal conjugate plane in the reflected beam beyond said turning mirror, said detector means (21) being positioned optically beyond said diaphragm stop at a pupillary image conjugate plane to receive said reflected light from said scanning element which passes back along the path toward said turning mirror, said turning mirror providing a stop for only the central portion of said reflected beam.
Claim 14
Dependent Claim
20 words
An ophthalmoscope as claimed in claim 12, characterised in that said diaphragm stop is constructed to have a variable aperture.
Claim 15
Dependent Claim
48 words
An ophthalmoscope as claimed in any preceding claim, characterised by an acousto-optical modulator (41) positioned to modulate said laser beam, and program means (34) for programming the modulation of said laser beam by the acousto-optical modulator to present specific graphic patterns in the scanning of said fundus area.
Claim 16
Dependent Claim
55 words
An ophthalmoscope as claimed in claim 14, characterised by prisms (32) optically coupled with said acousto-optic modulator (41) to provide for substantially the same angle of emission of laser beams of different incident wave length from the acousto-optic modulator at the same time preserving the Bragg relationship for the different wavelengths within the acousto-optic modulator.
Claim 17
Dependent Claim
68 words
An ophthalmoscope as claimed in claim 9, characterised in that said polygonal reflector (15) is rotated at a speed to produce a scanning frequency along said first coordinate on said fundus area of substantially 15.75 kHz and said second scanning element (17) produces a scanning motion in a direction normal to said first coordinate at substantially 60 Hertz and wherein said display means includes a television raster device.
Claim 18
Dependent Claim
81 words
An ophthalmoscope as claimed in claim 1, characterised in that said scanning laser beam is directed through a pivot point in a plane having a location selected relative to the laser beam for introducing the scanning laser beam into the eye being examined through a small portion only of the eye pupil, and wherein said scanning beam travels from said pivot point onto a wide-angle region of the fundus of the eye located with the eye pupil at said selected plane.
Claim 19
Dependent Claim
55 words
An ophthalmoscope as claimed in claim 15, characterised in that the size of the cross sectional area of said reflected beam is defined by the image at a conjugate plane of the exit aperture of said system, the exit aperture of said system being substantially larger than the entrance aperture for said scanning laser beam.
Claim 20
Dependent Claim
41 words
An ophthalmoscope as claimed in any preceding claim, characterised in that said detector is positioned to receive substantially only light reflected directly from the specific portion of the scanned area which is illuminated by the laser beam at any given time.
Claim 21
Dependent Claim
50 words
An ophthalmoscope as claimed in any of claims 1 to 18, characterised in that said detector is positioned to receive only light reflected from a specific portion of said scanned area which is illuminated indirectly from the portion of said scanned are which is illuminated directly at any given time.
Claim 22
Dependent Claim
24 words
An ophthalmoscope as claimed in claim 1, characterised in that said exit aperture is defined by the size of the pupil of said eye.
Claim 23
Dependent Claim
60 words
An ophthalmoscope as claimed in any preceding claim, characterised by means for sensing the position of successive facets of the first scanning element and providing a position signal indicating the time when each successive facet occupies the same position, said position signal being provided to the display means to control the timing of horizontal lines produced on said display means.
Claim 24
Dependent Claim
19 words
An ophthalmoscope as claimed in claim 22, characterised in that said display means is a two-dimensional television type raster.
Claim 25
Dependent Claim
30 words
An ophthalmoscope as claimed in any preceding claim, characterised by means for stopping said laser beam from scanning said eye fundus whenever a safety defect is sensed in said ophthalmoscope.
Claim 26
Dependent Claim
52 words
An ophthalmoscope as claimed in claim 22, characterised by means for stopping said laser beam from scanning said eye fundus, and wherein said position signal is provided to said means for stopping said laser beam to stop said laser beam from scanning during the time when said horizontal trace is not displayed.
Claim 27
Dependent Claim
18 words
An ophthalmoscope as claimed in any preceding claim, characterised in that said detector means is an avalanche diode.
Claim 28
Dependent Claim
105 words
An ophthalmoscope as claimed in claim 1, characterised by platform means for supporting said ophthalmoscope to provide movement of said ophthalmoscope for changing the angle at which said laser beam enters the pupil of the eye without changing the relative positions of the laser source, optical system and beam detector means, said platform means being mounted to allow translational movement of said ophthalmoscope only along two axes perpendicular to the axis of rotation of said rotating element and one axis parallel to said axis of rotation, and to allow rotational movement of said ophthalmoscope only about an axis parallel to the said axis of rotation.
Claim 29
Dependent Claim
97 words
An ophthalmoscope as claimed in claim 14, characterised by a control circuit, said acousto-optical modulator having an electrical driver and an electromechanical transducer, said driver controlling the optical characteristics of said transducer to allow said laser beam to impinge upon said first scanning element or to be deflected away from said first scanning element, wherein said driver comprises an RF oscillator, a balanced modulator having a video input, and a coupling circuit coupling said RF oscillator to said modulator, said control circuit providing signals to said video input in accordance with a program from said program means.
Claim 30
Dependent Claim
95 words
An ophthalmoscope as claimed in claim 24, characterised in that said acousto-optical modulator comprises an electrical driver, and an electromechanical transducer, said electrical driver controlling the optical characteristics of said electromechanical transducer to allow said laser beam to impinge upon said first scanning element or to be deflected away from said first scanning element, and wherein said driver comprises an RF oscillator, a balanced modulator and a coupling circuit coupling said RF oscillator to said modulator, said laser beam being stopped from scanning by interrupting the coupling between said RF oscillator and said balanced modulator.
Claim 31
Dependent Claim
39 words
An ophthalmoscope as claimed in any of claims 1 to 10, characterised by a telescope having a magnification different than one positioned between said reflective means and said eye pupil for adjusting the beam focus on said fundus area.
Claim 32
Dependent Claim
236 words
Apparatus for providing a two-dimension al output representation of the optical reflection characteristics of a scanned object, said apparatus being characterised by an optical source for generating an optical input beam of defined cross sectional area, a first scanning element comprising a rotatable multi-faceted polygonal reflector positioned to intercept said input beam and to reflect said input beam onto the object to be scanned, means for rotating said polygonal reflector at a sufficient speed to generate a scanning motion of said input beam along a first coordinate on said object at a predetermined frequency, the dimension along said first coordinate of each facet of said polygonal reflector being large compared to the cross sectional area of said input beam in the scanning direction, means for directing light reflected from said scanned object back onto the same facet of said polygonal reflector which reflected the light from the input beam onto the object, said reflected light being collected across a cross sectional area which is defined by the image at a conjugate plane of an optical exit aperture which is substantially larger than the cross sectional area of said input beam, optical detector means positioned to receive the light collected from said scanned object, which is reflected back from said polygonal facet, to provide a time varying output signal correlated with the scanning frequency of said input beam, and output means for receiving said time varying signal.
Claim 33
Dependent Claim
236 words
Apparatus for providing a two-dimension al output representation of the optical reflection characteristics of a scanned object, said apparatus being characterised by an optical source for generating an optical input beam of defined cross sectional area, a first scanning element comprising a rotatable multi-faceted polygonal reflector positioned to intercept said input beam and to reflect said input beam onto the object to be scanned, means for rotating said polygonal reflector at a sufficient speed to generate a scanning motion of said input beam along a first coordinate on said object at a predetermined frequency, the dimension along said first coordinate of each facet of said polygonal reflector being large compared to the cross sectional area of said input beam in the scanning direction, means for directing light reflected from said scanned object back onto the same facet of said polygonal reflector which reflected the light from the input beam onto the object, said reflected light being collected across a cross sectional area which is defined by the image at a conjugate plane of an optical exit aperture which is substantially larger than the cross sectional area of said input beam, optical detector means positioned to receive the light collected from said scanned object, which is reflected back from said polygonal facet, to provide a time varying output signal correlated with the scanning frequency of said input beam, and output means for receiving said time varying signal.
Claim 34
Dependent Claim
43 words
Apparatus as claimed in claim 31, characterised in that said output means includes display means for displaying an image in response to said time varying signal and having variations in said image corresponding with variations in light directly reflected from the scanned object.
Claim 35
Dependent Claim
58 words
Apparatus as claimed in claim 31, characterised in that a second scanning element is positioned in the optical path of said input beam from said source and first scanning element for directing said input beam onto the object to be scanned and for moving said input beam in a direction normal to the direction of said first coordinate.
Claim 36
Dependent Claim
17 words
Apparatus as claimed in claim 33, characterised in that said second scanning element includes a reflecting galvanometer.
Claim 37
Dependent Claim
30 words
Apparatus as claimed in claim 31, characterised in that the cross-sectional area of said collected light is large compared to the dimension in the scanning direction of said reflecting facets.
Claim 38
Dependent Claim
41 words
Apparatus as claimed in claim 33, characterised in that the rotation speed of said polygonal reflector is such that the scanning frequency of said input beam is substantially 15.75 kHz and wherein said output means includes a television-type raster imaging device.
Claim 39
Dependent Claim
80 words
Apparatus as claimed in claim 36, characterised by a second scanning element positioned in the optical path of said input beam from said source and first scanning element for directing said input beam onto the object to be scanned and for moving said input beam in a direction normal to the direction of said first coordinate, said second scanning element being operated to produce a scanning frequency in the direction normal to said first coordinate direction of substantially 60 Hz.
Claim 40
Dependent Claim
24 words
Apparatus as claimed in claim 37, characterised in that said rotating polygonal reflector has a number of facets which is evenly divisible into 525.
Claim 41
Dependent Claim
41 words
Apparatus as claimed in claim 31, characterised in that said detector is positioned to receive substantially only light reflected directly from the specific portion of the scanned object which is illuminated by the input beam at any given point in time.
Claim 42
Dependent Claim
49 words
Apparatus as claimed in claim 31, characterised in that said detector is positioned to receive only light reflected from a specific portion of said scanned area which is illuminated indirectly from the portion of said scanned area which is illuminated directly by the input beam at any given time.
Claim 43
Dependent Claim
21 words
Apparatu s as claimed in claim 31, characterised in that said optical source includes a laser for generating said input beam.
Claim 44
Dependent Claim
17 words
Apparatus as claimed in claim 31, characterised in that said optical detector means is an avalanche diode.
Claim 45
Dependent Claim
41 words
Apparatus as claimed in claim 32, characterised in that said output means includes a multiple line raster imaging device and wherein said rotating polygonal reflector has a number of facets which is evenly divisible into the number of displayed raster lines.
Claim 46
Dependent Claim
44 words
An optical element for use in an apparatus for optically scanning an image and producing a multiple line raster display of said image, comprising a multifaceted polygonal reflector having a number of facets which is evenly divisible into the number of displayed raster lines.
Claim 47
Dependent Claim
44 words
An optical element for use in an apparatus for optically scanning an image and producing a multiple line raster display of said image, comprising a multifaceted polygonal reflector having a number of facets which is evenly divisible into the number of displayed raster lines.
Claim 48
Independent Claim
189 words
A method for providing a two-dimensional output representation of the optical reflection characteristic of an eye fundus, said method comprising the steps of directing a laser input beam of selected cross-sectional area small compared to the cross section of the pupil of said eye onto a reflective means of a scanning device, and operating said scanning device to scan light reflected from said reflective means onto a segmental portion of the eye fundus with a scanning motion of selected rate along a first coordinate, configuring said reflective means to intercept and reflect to the object substantially all of said input beam, directing light reflected from the scanned object back to said reflective means of said scanning device, forming said light reflected back from said scanning device into an output optical beam, stopping a central portion of said reflected output beam cross-sectional size equal to the input beam cross-sectional area, detecting the portion of the output optical beam reflected by the first scanning device to provide a time-varying electrical signal correlated to the scanning rate of said input beam, and producing said output representation in response to said time-varying signal.
Claim 49
Independent Claim
189 words
A method for providing a two-dimensional output representation of the optical reflection characteristic of an eye fundus, said method comprising the steps of directing a laser input beam of selected cross-sectional area small compared to the cross section of the pupil of said eye onto a reflective means of a scanning device, and operating said scanning device to scan light reflected from said reflective means onto a segmental portion of the eye fundus with a scanning motion of selected rate along a first coordinate, configuring said reflective means to intercept and reflect to the object substantially all of said input beam, directing light reflected from the scanned object back to said reflective means of said scanning device, forming said light reflected back from said scanning device into an output optical beam, stopping a central portion of said reflected output beam cross-sectional size equal to the input beam cross-sectional area, detecting the portion of the output optical beam reflected by the first scanning device to provide a time-varying electrical signal correlated to the scanning rate of said input beam, and producing said output representation in response to said time-varying signal.
Claim 50
Dependent Claim
20 words
A method as claimed in claim 45, characterised by the further step of compensating for astigmatism in said reflective means.
Claim 51
Dependent Claim
74 words
A method as claimed in claim 45, characterised by the further steps of illuminating said object with said scanning input beam through a selected small input aperture, illuminating said detector with said output beam through a selected large exit aperture concentric with said input aperture, locating said reflective means of said first scanning device at a conjugate plane of said output aperture, and locating said detector at a conjugate plane of said output aperture.
Claim 52
Dependent Claim
28 words
A method as claimed in claim 45, characterised by the further step of locating means for detecting said output beam at a conjugate plane of the eye fundus.
Claim 53
Independent Claim
213 words
A method for providing a two-dimensional output representation of the optical reflection characteristic of a scanned object, said method comprising the steps of directing an optical input beam of selected cross-sectional area onto reflective means of a scanning device, and operating said scanning device to scan light reflected from said reflective means through a selected small central input aperture onto a segmental portion of the object with a scanning motion of selected rate along a first coordinate, configuring said reflective means to intercept and reflect to the object substantially all of said input beam, directing light reflected from the scanned object back to said reflective means of said scanning device through an exit aperture large compared to said input aperture and concentric with said input aperture, forming said reflected light into an output optical beam which overfills said reflective means along said first coordinate, so that said first scanning reflects only a portion of the output beam at any time, said reflective means being located at a conjugate plane of said exit aperture, detecting the portion of the output optical beam reflected by the first scanning device to provide a time-varying electrical signal correlated to the scanning rate of said input beam, and producing said output representation in response to said time-varying signal.
Claim 54
Independent Claim
213 words
A method for providing a two-dimensional output representation of the optical reflection characteristic of a scanned object, said method comprising the steps of directing an optical input beam of selected cross-sectional area onto reflective means of a scanning device, and operating said scanning device to scan light reflected from said reflective means through a selected small central input aperture onto a segmental portion of the object with a scanning motion of selected rate along a first coordinate, configuring said reflective means to intercept and reflect to the object substantially all of said input beam, directing light reflected from the scanned object back to said reflective means of said scanning device through an exit aperture large compared to said input aperture and concentric with said input aperture, forming said reflected light into an output optical beam which overfills said reflective means along said first coordinate, so that said first scanning reflects only a portion of the output beam at any time, said reflective means being located at a conjugate plane of said exit aperture, detecting the portion of the output optical beam reflected by the first scanning device to provide a time-varying electrical signal correlated to the scanning rate of said input beam, and producing said output representation in response to said time-varying signal.
References Cited (Backward Citations)
US4213678A
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