WO1994018883A1 - Systeme de compensation des mouvements lateraux d'une cible - Google Patents

Systeme de compensation des mouvements lateraux d'une cible Download PDF

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Publication number
WO1994018883A1
WO1994018883A1 PCT/US1994/002007 US9402007W WO9418883A1 WO 1994018883 A1 WO1994018883 A1 WO 1994018883A1 US 9402007 W US9402007 W US 9402007W WO 9418883 A1 WO9418883 A1 WO 9418883A1
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WIPO (PCT)
Prior art keywords
eye
sensing detector
detector means
position sensing
contrast
Prior art date
Application number
PCT/US1994/002007
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English (en)
Inventor
Carl F. Knopp
Jerzy Orkiszewski
Jan Wysopal
Hanna J. Hoffman
Original Assignee
Phoenix Laser Systems, Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Phoenix Laser Systems, Inc. filed Critical Phoenix Laser Systems, Inc.
Priority to AU62496/94A priority Critical patent/AU6249694A/en
Publication of WO1994018883A1 publication Critical patent/WO1994018883A1/fr

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Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B3/00—Apparatus for testing the eyes; Instruments for examining the eyes
    • A61B3/10—Objective types, i.e. instruments for examining the eyes independent of the patients' perceptions or reactions
    • A61B3/113—Objective types, i.e. instruments for examining the eyes independent of the patients' perceptions or reactions for determining or recording eye movement
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F9/00—Methods or devices for treatment of the eyes; Devices for putting-in contact lenses; Devices to correct squinting; Apparatus to guide the blind; Protective devices for the eyes, carried on the body or in the hand
    • A61F9/007—Methods or devices for eye surgery
    • A61F9/008—Methods or devices for eye surgery using laser
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B17/00—Surgical instruments, devices or methods, e.g. tourniquets
    • A61B2017/00681—Aspects not otherwise provided for
    • A61B2017/00694—Aspects not otherwise provided for with means correcting for movement of or for synchronisation with the body
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F9/00—Methods or devices for treatment of the eyes; Devices for putting-in contact lenses; Devices to correct squinting; Apparatus to guide the blind; Protective devices for the eyes, carried on the body or in the hand
    • A61F9/007—Methods or devices for eye surgery
    • A61F9/008—Methods or devices for eye surgery using laser
    • A61F2009/00844—Feedback systems
    • A61F2009/00846—Eyetracking
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F9/00—Methods or devices for treatment of the eyes; Devices for putting-in contact lenses; Devices to correct squinting; Apparatus to guide the blind; Protective devices for the eyes, carried on the body or in the hand
    • A61F9/007—Methods or devices for eye surgery
    • A61F9/008—Methods or devices for eye surgery using laser
    • A61F2009/00878—Planning
    • A61F2009/00882—Planning based on topography

Definitions

  • This invention relates to tracking systems for aiming a laser beam and/or positioning projected light patterns at a known relation onto moving targets.
  • the invention is concerned with the detection of, measuring of and compensating transverse movements of optical targets such as an eye during ophthalmic laser surgery as well as non-surgical diagnostic procedures.
  • the present invention is particularly powerful when taken in conjunction with a method for capturing, measuring and compensating for movements along the axial direction such as disclosed by Wm. D. Fountain in U.S. Patent
  • the present invention emphasizes those aspects and specific embodiments of a transverse 2D tracker that are most critical in allowing a laser beam or projected light patterns to be correlated with and/or directed to a specific location on the target regardless of its lateral movement. Since the application to eye surgery places the most stringent requirements on the tracker, the present invention is described mostly in reference to this application. However, it is to be understood that the invention is broadly applicable to any situation involving precision diagnostic measurements and/or laser operations on moving targets, including industrial applications, such as in semiconductor processing where laser annealing and other techniques call for precise alignment of a mask onto a substrate in the presence of vibrations.
  • tracking can serve an important function in allowing cross-registration of successive readings taken across a moving target.
  • the effects of target motion can be compensated for via programming in the computer (i.e., software).
  • utilization of transverse tracking especially in concert with a depth tracking method that can keep the distance to the eye constant, e.g., as was disclosed in co-pending U.S. patent application Serial No. 945,207, opens up the prospect of performing true point-by-point thickness and curvature measurements with standard scanning techniques.
  • stabilization of a moving target requires defining the target, characterizing the motion of the target, and readjusting the aim of the optical system repeatedly in a closed-loop fashion.
  • requirements for a tracking system are set by the type of eye motion, which fall into three categories: microsaccades, drift and high frequency tremor.
  • the high frequency tremors of about 90 Hz set an upper limit to the frequency, but are of a very small amplitude (up to 40 seconds of arc).
  • icrosaccades are highly accelerated motions with constantly changing directions but lower frequencies (a few Hz). These small but rapid eye movements, combined with slow drift (about 1 minute arc/sec), prevent the retinal image from fading.
  • requirements set for lateral eye tracking should include, as a goal, the ability to respond to movement with accelerations of up to 40,000 deg/sec2. This translates to amplitudes of about 1 degree at maxi um frequencies of 100 Hz and increasing to nearly 15 degree at 20 Hz.
  • Optical point trackers utilize various lens-like properties of the eye to locate optically distinguished locations such as the first, second, third and fourth Purkinje points.
  • Crane and Steele describe a dual Purkinje projection technique to compare the displacement of two different-order Purkinje projections over time, and a repositioning apparatus to adjust the isometric transformation corresponding to the motion. Similar application of dual Purkinje technique to a stabilized visual system was advanced by Crane (U.S.
  • Patent No. 4,443,075 using a fundus illumination and monitoring device.
  • These and similar Purkinje image-based tracking methods purport to follow the movement of the anterior surface of the eye. While such techniques possess, in principle, sufficient speed to follow the displacement of Purkinje points, they do include an implicit assumption that the eye moves as a rigid body. In reality, however, the eye does not move as a rigid body, hence localization of the Purkinje points can be influenced by transient relative motions between the various optical elements of the eye, which leads to fictitious position information for identifying the surface of the cornea. In addition, such systems are rather complex and tend to exhibit large interperson variability in their calibration setting, which requires continuous real-time adjustments of the amplitude of the controlling signals.
  • the other class of tracking methods suggested in prior art involve, in one form or another, digital correlation techniques. These include retinal image trackers and various pattern recognition algorithms involving edge detection techniques. In either case, very fast frame-rate CCD cameras and sophisticated processing algorithms are required along with fast servo- controlled mirrors closing the loop. This is because, in general, methods based on pattern recognition are fundamentally digital, requiring high frequency updates. With the frequency response limited in practice to about one tenth the update frequency, digital signal comparisons are considered to be relatively slow. In the case of tracking eye motions, setting the sampling frequency to about an order of magnitude higher than the highest frequency to be pursued translates into kHz rates, leaving less than one thousandth of a second for processing the signal information.
  • CCD cameras are used to analyze the translations of an image on the retina from which the resulting coordinate transformation could be computed.
  • the data is then fed to e.g., galvanometric driven mirrors which are repositioned so as to maintain a beam at the selected location of the subject.
  • galvanometric driven mirrors which are repositioned so as to maintain a beam at the selected location of the subject.
  • Patent 4,848,340 describe a simpler variant on the pattern recognition method, whereby a grid is marked, using a laser, on the epithelial surface of the cornea, in a known reference alignment to the eye's visual axis.
  • An infrared optical system monitors reflections therefrom, generating an error signal whenever the position of the mark deviates from reference alignment.
  • the error signal is transmitted to a laser guidance system containing a fine tuner (consisting, e.g., of one or more galvanometrically controlled mirrors) which steers the laser beam in a manner that reduces the error signal to null.
  • This type of a tracking system requires a sensor such as a photodiode array that can detect variations in the intensity of the reflected light pattern to generate signals representative of grid movements.
  • sensors suffer from both slow response times and limited spatial resolutions.
  • accuracy bounds set by the space between the array elements divided by the magnification it is difficult to obtain resolutions better than 50 microns or so in practical systems.
  • the technique taught by Bille et al. is digital in nature, which means that it suffers from similar drawbacks as image trackers and edge detectors in general, including processing speeds limited by the servo rate to less than a millisecond.
  • a target tracking and laser positioning mechanism that relies on a mark on the surface of the cornea in order to perform corneal surgery, such as described by Bille's tracking method, might lead to misdirected positioning of laser lesions below the surface when combined with any suitable focused laser.
  • the mark would change its absolute location due to changes in the structure and shape of the material being modified that are caused by use of a laser surgery instrument itself, rather than by eye motions. It is therefore not clear that a tracking method based on marking the target tissue itself is compatible with laser surgical interventions performed simultaneously with the tracking.
  • one of the features of the present invention is to enable non-incisive procedures inside target tissues by remote means. It would hence be counterproductive to mark the surface of the cornea for the sole purpose of following the motion of said mark.
  • the tracking is based on a reference provided by an empirically determined offset between the eye's symmetry axis and the eye's visual axis. It is claimed that tissue can be tracked by monitoring the reflection from the apex of the cornea, thus avoiding the need to mark the eye, and/or, rely solely on patient fixation. However, with this technique, the tracking does not follow tissue features generally corresponding to the targeted surgical site itself. Instead, Bille et al.'s technique tracks reference points that are, like Purkinje points, a property of the optical system and do not correspond to any particular physiological tissue. They are therefore separate, remote from and may be unrelated to the targeted surgical site.
  • the accuracy of the tracking is thus compromised in direct proportion to the degree of the reference points' remoteness relative to the surgical site, while ambiguities inherent in measurements of the symmetry and/or the visual axis will further reduce the accuracy with which positional changes of the targeted surgical site can be pursued using these methods.
  • the methods of the present invention disclosed herein involve contrast tracking which does not rely on well-defined edges and/or patterns that must be compared to some reference. This allows great flexibility in selecting the tracking landmark, since prominent and constant edges are not required for acceptable signal-to-noise ratios.
  • the tracking information is to be obtained through means contiguous to the target region, which is mechanically and structurally considered as part of it, but is unlikely to be affected by the course of the laser intervention.
  • the system and techniques disclosed herein resolve, for the first time, difficulties associated with previous attempts at limbus tracking.
  • the limbus located at the outer edge of the cornea, presents several advantages as a tracking landmark for corneal procedures.
  • the present invention overcomes these shortcomings because it is practical even in the absence of prominent, well-defined or even temporally constant edges.
  • the only two requirements are that sufficient contrast be present, and that the feature possess a degree of symmetry. In the eye, these conditions are fulfilled by e.g., the limbus structure and in most cases, the pupil as well.
  • a method for tracking the limbus was disclosed relying on a set of two quadrant detectors as the position sensor.
  • the present patent application expounds on that disclosure by highlighting a unique electronic control system that can be used for the tracking to great advantage, and including as a desirable feature a dual feedback loop that can be all analog, thus significantly increasing the practical speed of operations over comparable digital methods.
  • the simplified signal processing and fast logic operations involved in the electronic servo loops of the present invention also allow a substantial expansion of the scope of the previously disclosed limbus tracking method to include other contrast-based tracking landmarks and alternative position sensing detectors as may be needed to implement tracking in different surgical, diagnostic or industrial settings.
  • the moveable optical element is under the directional control of a rapid servo device.
  • Still another specific object of the invention is to enable, in a preferred embodiment, all analog execution of electronic servo functions, if desired, including those that provide directional control of the moving optical element, thus circumventing difficulties associated with the slower all- digital closed loop servo systems.
  • an embodiment of the present invention comprising a method and apparatus for precise lateral target tracking useful to ocular surgery and ophthalmic diagnostics, as well as to several other medical and industrial procedures.
  • the techniques disclosed are particularly powerful in combination with an axial (Z) tracking system, such as the modified confocal microscopy-based technique disclosed by Wm. D. Fountain in U.S. Patent No. 5,162,642 and in U.S. patent application Ser. No. 945,207.
  • the Z-tracker discussed therein is fully compatible with the present system with which it can interface by way of suitable coupling optics and/or the tracking optical element itself, provided that the objective lens assembly is inserted as the first element in front of the target.
  • the present invention also contains provisions, such as additional coupling optics, for interfacing the X-Y tracker with any number of other optical subsystems including, but not limited to, imaging means, laser targeting and treatment means and topography means.
  • additional coupling optics for interfacing the X-Y tracker with any number of other optical subsystems including, but not limited to, imaging means, laser targeting and treatment means and topography means.
  • the tracking system of this invention fulfills an important dual-use purpose: it can greatly enhance the precision of lesion placement in targets as well as improve safety margins by allowing simultanecus presentation of a stationary view (e.g., in the form of continuously updated video image) of a given section of tissue on a display monitor.
  • the transverse tracker of this invention can be operated in a manner allowing determination of target movement relative to a given coordinate system which is in a known reference to, e.g., the optical axis of the apparatus. Such movement can then be compensated for by software means using programming in the computer.
  • the ability to actually compute and store information concerning target movement in a meaningful way is a valuable tool whenever sequential series of measurements are to be performed by way of e.g., scanning the target while it is moving, so that the results can be extrapolated to reveal a global feature of said target.
  • Such an approach can be profitably applied to topographic and pachymetric measurements aimed at reconstructing, on a point-by-point basis, the curvature, shape and/or thickness of intra-ocular structures such as the cornea and the lens.
  • other existing instrumentation such as slit lamps and cameras, a host of new possibilities opens up for cross-correlating various optical target properties across wider areas and with higher local accuracies than was demonstrated with any prior art methods.
  • the system and m thods of the present invention can be used successfully to suppress vibrations in various semiconductor processing applications involving micron and sub-micron precision levels.
  • Implementation of a tracker to detect and compensate for random environmental vibrations may alleviate the need for expensive and cumbersome isolation equipment, thus leading to significant reductions in capital outlay costs while improving overall yields.
  • the system and method of the present invention rely on returning an error signal generated by movement of the target to zero.
  • This is where similarities to other tracking methods end.
  • the key novel feature embodied within the present invention which distinguishes it from prior art concerns an approach to generating tracking signals by way of detecting variations in target contrast, thereby avoiding the need for complex edge detection algorithms. Consequently, position sensing detectors with continuous resolution elements can be utilized, thus eliminating information gaps while avoiding the need for high update frequencies.
  • the electronic control system is compatible with fast, simple, all-analog techniques for processing the signals from position sensing detectors and/or transducers and translating them into command signals for a servo control mechanism. Such an analog option is not feasible with other tracking methods based on digital data acquisition systems.
  • the tracking system is at least comprised of an illumination source, a sensor, a moveable optical element, such as a mirror, a two-dimensional logic board, and a dedicated microprocessor or logic board including appropriate signal processing firmware and software. Interfaces with other system elements such as laser aiming, target viewing and/or depth ranging subsystems may all be included as part of the optical train, while suitable control ports provide alectronic interface with these other functions as well as with a central computer (using A/D converters where required).
  • the transverse tracker disclosed herein is thus best considered as a module ready to be integrated with other system functions, be they diagnostic or therapeutic in nature.
  • the illumination light is projected off-axis relative to the optical axis of the instrument so as to minimize interference from either the treatment light (typically an intense laser beam) or depth ranging light (which can also be a laser, such as a low power HeNe).
  • the treatment light typically an intense laser beam
  • depth ranging light which can also be a laser, such as a low power HeNe.
  • the position sensors are also selectable from among a class of position-sensing photodetectors, all possessing fast response times (of well below a tenth of a millisecond) and excellent resolutions (on the order of 1 micron), with a view towards optimizing a given system performance.
  • the transverse X-Y tracking detector consists of a set of two high speed quadrant detectors which provide an ideal match to tracking the limbus of the eye.
  • Alternative detectors including lateral-effect and superlinear position sensors, may however be selected for eye tracking or other applications, without compromising the effectiveness of the present invention.
  • An X-Y logic board comprises a key element of the electronic processing serving as the central "switchboard" of the servo tracking loop. This is where voltage signals from the detectors corresponding to target motion are received and converted to appropriate commands for controlling the tracking optical element assembly drivers so as to compensate for said target motion by repositioning an movable optical element, such as a mirror. Since analog control signals can be used, processing speeds are not a limiting factor, even for applications requiring high repetition rate (>1 kHz) lasers. Thus, laser firing can therefore always be disabled, if necessary.
  • either piezoelectric, electro ⁇ magnetic or galvanometric drives can be used to steer the moveable system element, such as a mirror to drive the error signal generated by target motion back to null.
  • This component must however be capable of moving with sufficiently high acceleration and velocity to compensate for the fastest motion possible by the intended target. Since the operation of the system is not limited by either the processing speed of the servo loops or the detectors' response time, the driven optical element with its finite moment of inertia is likely to provide the main limitation on the extent and rate of motion which can be compensated, so considerable care must be exercised in selecting the type of drive to match a given application needs. Nonetheless, the manner of operation and the principles of the present invention do not depend on specific drive mechanism, a particular transducer, or the moveable optical element, all of which components can therefore be selected to match the needs of specific applications.
  • Intrinsic to the tracking scheme disclosed herein is the choice of a suitable tracking landmark possessing of sufficient contrast under illumination by the light source used. This is a relatively easy condition to fulfill, lending the system considerable flexibility with regard to said choice.
  • the tracking landmark would be located contiguous and in proximity to the targeted tissue, yet without being coincident with the precise target site itself, since this site will change during the course of the intervention.
  • the eye limbus at the rim of the cornea provides sufficient contrast to serve as the tracking landmark for procedures affecting either the central or peripheral portions of he cornea.
  • Alternative landmarks such as the pupil, which may be useful when procedures in zones peripheral to the visual axis are contemplated, also fall under the domain of this invention.
  • a suitable feature can usually be artificially impressed upon the workpiece in sufficient proximity to the target site and with enough contrast to allow the efficacious employment of the tracking methods discussed in this invention.
  • FIG. 1 is a schematic block diagram of the transverse tracker, its associated optical and electronic elements, and the information flow, electronic feedback control paths and servo loops.
  • the tracker is configured for tracking an arbitrary landmark, shown for illustration purposes as a circle.
  • FIG. 2 is a schematic elevation of an example of incident and reflected light rays for an illumination system corresponding to a preferred embodiment of the invention in which the limbus of the eye provides the tracking landmark. Attention is drawn to the fact that the scattered component of the reflected light is selected for defining target contrast.
  • FIG. 3 is a schematic block diagram illustrating in more detail the key functions and components of the X-Y logic board in relation to the various interdependent electronic control loops as well as devices considered external to the tracker, such as the CPU and a laser controller.
  • FIG. 4 is a graph depicting, for one axis, an example of transducer voltage dependence on optical element motion, expressed in degrees.
  • FIG. 5 is a front view of some key components of an X-Y mirror, used as the moving optical element in one preferred embodiment of the tracker.
  • FIG. 5A is a side view of the same X-Y tracking mirror.
  • FIG. 6 shows an optical image of the iris, sclera and pupil of the eye, incident on a two quadrant detector configuration used as the position sensing detector in one preferred embodiment of the invention. Also indicated in Figure 6 are the equations used to obtain the position signals when either one or both detectors are used.
  • FIG. 7 illustrates another example of a sensor useful to the present invention, comprising, in this case, a lateral- effect detector configuration. The appropriate X and Y position signals are again indicated.
  • FIG 1 is a schematic of a preferred embodiment of the transverse tracking assembly 10, shown here as tracking a symmetrical landmark 1 belonging to an arbitrary moving target.
  • Figure 2 shows the specific target consisting of an eye 62 ujing the limbus 3 as a tracking landmark, which situation pertains to certain ophthalmic surgery and diagnostics procedures. While ophthalmic interventions comprise one primary application that falls under the domain of the present invention, it is to be understood that the target tracking system disclosed herein encompasses other types of medical diagnostic and surgical procedures as well as non- medical and industrial operations, involving high precision operations on objects subject to random movement.
  • the system 10 employs an optical train consisting at least of illumination source(s) 8, system optics 5 including, preferably, an objective lens assembly 90 defining the axial (Z) direction, a movable system element 9, imaging optics 6, and a receiver assembly 30 which includes detectors 31.
  • the optics designated 91 are optional and may include further components to permit interfacing the tracking system to other assemblies such as an axial tracker, a target viewing means, a treatment laser aiming system and others, as dictated by particular application needs.
  • the electronic subsystem also shown in Figure 1 consists of electric signals 39 from the sensors 31, an X-Y logic board 40 controlled (line 51) by a central processing unit (CPU) 50 which includes system software 100 to aid in the interface to other assemblies, X and Y servo drivers 41, 42, and the associated relay paths 43 and 44 to actuators 23 and 24 that control orientation of the moving element assembly 9 along its respective X and Y axes.
  • CPU central processing unit
  • X and Y servo drivers 41, 42 and the associated relay paths 43 and 44 to actuators 23 and 24 that control orientation of the moving element assembly 9 along its respective X and Y axes.
  • the optical portion of the tracking path shown in Figure 1 comprises several steps.
  • Light 36 from the illuminators 8 is projected onto the target, reflected from the tracking landmark 1, passes through the system optics 5 which may include an objective lens 90 acting to collect and collimate the light along path 38, whereupon it impinges upon the moving system element 9, shown here as a reflecting surface that may be part of, e.g., an X-Y tracking mirror (it could be a lens).
  • the light is then propagated via interface optics 91 to imaging optics 6 which focus the light onto detectors 31 contained in the receiver assembly 30.
  • a lune-shaped pattern 20 is projected in this manner, consisting of a bright field corresponding to one side of the tracking boundary adjacent to a darker field representing scattered light from the other side thereof, which together represent the target contrast.
  • the sensors 31 may consist of one or several coupled detectors, preferably with a continuous detecting surface, and arranged so as to produce voltage change information 39 in response to variations in the position of the illumination centroids. As the target moves, so does the high contrast boundary, thereby altering the signal(s) produced by various parts of the sensor(s), as will be apparent from subsequent discussion accompanying specific embodiments of the sensors (per Figures 6 and 7 below).
  • the transverse tracker of the present invention is intended for use with an ophthalmic laser surgery instrument, as was disclosed in co-pending U.S. patent application Ser. No. 843,347 and which is incorporated herein by reference.
  • the eye must be tracked without incurring undue interference from a bright treatment laser, which is simultaneously on-line with the tracker.
  • off-axis illumination source(s) 8 may be utilized in this case, with said sources consisting of, e.g., a bright lamp (such as tungsten) coupled to fiber optics bundle and projected through lens(es) 88 onto the general region of the cornea 4 of eye 62.
  • the limbus 3 at the outer rim of the iris comprises the boundary used as the tracking landmark.
  • the X-Y logic board 40 which serves as the central "switchboard" of the electronic tracking loop.
  • the board can quantify and correlate target movement with intensity changes at the detector; compute the required displacements of the moving element, such as a mirror, necessary to compensate for said motion; effect the appropriate analog control signals to the moving element control assembly; and issue digital commands to a laser firing controller, following analog to digital (A/D) conversion where applicable.
  • the board is where the X-Y coordinate shifts (magnitude and direction) are first computed from the voltage signals produced by the sensor, based on formulas applicable to specific detectors that are contained within the sensors interface 15. Preferably using embedded firmware, the board converts these coordinate values into mirror angular corrections which are relayed to servo drivers 41 and 42 via control lines 16 and 17, respectively (via switches 11 and 12 in a different position from what is shown in Figure 1, as will be apparent from further discussion below).
  • the servo drivers activate, in turn, actuators 23 and 24 by way of control signals 43 and 44, which causes the X-Y mirror assembly to pivot about its axes, thus effectively changing its orientation to pursue the motion of the target, and stabilizing it with respect to system 10.
  • the X-Y logic board contains two switches 11 and 12 relating to X and Y displacements respectively. These switches allow interchanging of the servo driver connections between transducers 21 and 22 and detector signals 39, representing the two modes of operation inherent to the functioning of the two-dimensional tracker that is the subject of this disclosure, as discussed further below.
  • the two transducers 21 and 22 are also labeled X and Y, corresponding to the two orthogonal axes lying in the plane perpendicular to the optical axis.
  • These position sensing elements fulfill an important dual function in the operation of system 10 by allowing the moving element 9 to either stabilize in the absence of a target, or to calibrate the actual magnitude and direction of the moving element's displacements, and therefore the target's (this latter situation being applicable to diagnostic measurements as will be elaborated further below) .
  • the transducers form an integral part of the moving element assembly 9, hence they represent target displacement vectors relative to that frame of reference.
  • each transducer consists of a simple "flag" — a low- cost type of position sensor consisting of a moving bar and a sensor, whereby angular displacements can be controlled and measured in a purely analog fashion, without the need for any convert commands or wait loops.
  • digital converters such as resolvers and Linear-Variable- Displacement-Transducers (LVDT) can also serve as transducers, if desired, with only minor modifications in the operation of system 10.
  • Figure 3 shows a more detailed view of the X-Y logic board schematics. For ease of illustration, only one switch is shown in the center of the figure, representing both X and Y switch functions 11 and 12, as these two always work in tandem.
  • the transducers which, for simplicity, are labeled as "flags" in Figure 3, are, in fact, to be understood as comprising any one of the general class of devices discussed above, and designated 21 and 22 in Figure 1.
  • the switches In one mode of operation (“tracking mode") the switches are set to position 18 ("closed"), whereupon the X and Y signals 13 and 14 representing new target positions are fed through the switches to X and Y servo drivers by way of control lines 16 and 17, thus activating the tracking feature.
  • the reference position is established upon commencing the tracking procedure as a nominal position.
  • this reference position is somewhat arbitrary, but can be set to reflect a convenient target orientation.
  • the reference position for the target in this case the eye, to which all subsequent signals are to be compared, is set by aligning the patient's line of sight with the optical axis of the instrument.
  • Such a position provides a relatively unambiguous determination of a reference point in space that is unique to each patient, as the nominal position of the eye relative to the instrument (i.e., to the position sensing detectors).
  • Tracking is initiated and stopped upon commands issued by the CPU 50 through control line 51 to a microprocessor interface 49.
  • Firmware 52 embedded within the microprocessor is applied to initialize logic to interact with the CPU and interpret commands from the CPU. Since the CPU 50 comprises, typically, a digital VME based bus, it is understood that provisions are included to issue the start/stop tracking commands in digital format. As indicated in Figure 3, issuing these commands is the main function of the CPU 50 and its associated software 100 in relation to the operation of the tracker alone; however, when the tracker of the present invention is part of a larger system, the CPU provides also an essential link for interfacing with other assemblies such as an axial tracker or a target viewing system.
  • Figure 3 also shows an error monitoring block 59 that is operatively connected via control line 55 to microprocessor interface 49, which, in turn, is seen to also command switches 11 and 12 as represented by relay line 56.
  • block 59 monitors (lines 53 and 54) the X,Y signals 13 and 14 and checks them against logic contained within the microprocessor interface.
  • the error monitoring block can instruct a laser controller to disable further operations such as laser firing, as indicated by control line 61.
  • This added capability to disrupt laser firing directly through the microprocessor interface 49 and independent of the CPU is regarded as a key safety enhancing feature provided within the tracker electronics.
  • the second mode of operation illustrated in Figure 3 is activated when the switches move to position 19 ("open"), thereby shifting system control to the transducers' interfaces 47 and 48, through connections 63 and 64. This mode of operation
  • This feature not only prevents the mirror from random oscillations, but also allows recovery of the tracking if it is momentarily lost through e.g., the blinking of an eye, or some momentary undue environmental vibration.
  • this mode of operation constitutes is feed-back loop, since the microprocessor is instructing, via control line 56 the servo drivers to reorient the moving element back to a default position, and the signals from the flags confirm that this position has, in fact, been attained. Once the default position has been confirmed, the switches 11 and 12 can again "close” (or move back to 18), and normal tracking may be resumed.
  • the microprocessor interface 49 receives continuous signals from the flags as indicated by control lines 65 and 66, which relate the moving element's absolute position. These signals can provide an additional monitoring function as to the proper functioning of the system and may also constitute one more input data on the basis of which the microprocessor determines whether to continue or interrupt the tracking procedure.
  • the motion of the eye lid can be rapidly detected through significant alteration of the relative contrast as perceived by the position sensitive detectors, which results in a large error signal (13 and 14).
  • the error monitoring block would then issue a signal 55 to the microprocessor interface.
  • Laser firing can then be i mediately interrupted through signals 61 leading directly from block 49. Since the servo drivers simultaneously cause a repositioning of the movable element by amounts exceeding previously set bounds, this deviation from normal parameter range is also sensed by the flags and transmitted to the microprocessor interface 49 (through 65 and 66).
  • the microprocessor issues a signal 56 to move the switch to position 19 thus setting tracking to stand-by mode.
  • tracking and firing can both be re ⁇ activated a short time later.
  • the manner in which tracking is resumed most effectively involves returning the moving element to the nominal position recorded just prior to the interruption, corresponding to a particular target contrast relationship stored in the microprocessor memory.
  • the function of the flags can be expanded to encompass, in alternative embodiments, still another role.
  • they may be used to obtain a direct read-out of the moving element's (and hence, target's) positions as an aid to diagnostics of randomly moving targets.
  • the voltage signals from the flags are first calibrated against deflection angles of the moving element relative to the pre-determined default position, with the resulting curve stored in the microprocessor interface logic 49.
  • the movable optical element comprises a reflecting mirror.
  • a voltage-to-angle calibration curve such as shown in Figure 4 can be obtained.
  • This situation may be representative of a diagnostic system aimed at acquiring topographic measurements of corneal surfaces, where it has been determined that a range of travel for the mirror of approximately 2 degrees around either axis is adequate to obtain desired local curvature accuracies (ideally better than 10 microns) .
  • the default position of the moving element related to the zero target position is somewhat arbitrary, its selection may be constrained by the fact that the same element is often required, in practice, to also serve as a principal reflecting surface for interfacing with other optical subsystems, such as a treatment laser, a viewing microscope and/or a depth ranger.
  • the zero position angle is set at 45 degrees which provides a convenient interface with other system optics as well as superior resolution properties for measuring target displacements. In this case all mirror angle computations, such as the ones shown in Figure 4, are calibrated relative to 45 degrees.
  • the method of contrast tracking disclosed herein is independent of the type of moving optical element control.
  • the motor drive may be based on either piezoelectric or electromagnetic principles.
  • a piezoelectric driver uses the change in shape of a quartz crystal in response to a electric current to move the element.
  • An electromagnetic driver uses a coil of wire in a magnetic field which is made to move by passing an electric current through the coil.
  • the electromagnetic driver is similar in function to a voice coil of an audio speaker. In either case, the speed (or, more accurately, the acceleration) of the entire tracking system is limited by the response of the drivers and the mirror's moment of inertia.
  • an electromagnetic drive using a voice coil means has been used successfully to reposition a mirror with high degree of accuracy (better than 10 microns) at accelerations of up to 40,000 deg/sec2 - sufficient to track even the fastest involuntary motions of the eye.
  • FIG. 5 An example of a mirror assembly based on this type of control is shown in Figure 5 with an expanded side view depicted in Figure 5A, corresponding to a preferred embodiment of the invention.
  • the mirror 70 is mounted with two pivot axes - X and Y, indicated as 73 and 74, respectively.
  • the outer gimbal ring 71 and the inner gimbal ring 72 allow the mirror to pivot about the X and Y axes respectively, as shown by the respective connections to the X and Y actuators 23 and 24.
  • Each actuator consists of a stationary component, which is the permanent magnet frame (indicated as 81 and 82 for X and Y, respectively) and a dynamic component comprising the voice coil windings, also one for each axis.
  • FIG. 5A A better view of these dynamic components is obtained from the side view of Figure 5A, where the windings are depicted in positions marked 83 and 84 respectively for the X and Y actuators.
  • the voice coil shuttles are seen in the locations marked 28 and 29.
  • the sensors and the transducers comprise the other two components of the full mirror drive assembly.
  • the sensors shown as 26 and 27 in Figures 5 and 5A, are stationary with respect to the actuators' permanent magnets while the flags 21 and 22 represent the dynamic components corresponding to the voice coil windings.
  • leads 75 and 76 linking the position sensors (or flags) to the X-Y logic board (via control lines 45 and 46, representing the same connections previously shown in Figure 1), and leads 78 and 79 which establish the electrical connections through which the servo drivers (designated 41 and 42 in Figure 1) control the mirror actuators (i.e., relay lines 43 and 44 per Figure 1).
  • any landmark on or within the target would suffice for defining the motion of said material, as long as it be possessed of sufficient contrast and a degree of symmetry.
  • the tracking landmark should be located contiguous to the targeted tissue and should mechanically respond in a manner similar to the targeted tissue.
  • the tracking landmark should be sufficiently removed from the location of any other operations by the system of which the tracker is a part, so as to minimize potential interference from sources of light other than the illumination used for the present tracker.
  • a further criterion for selection of the tracking landmark is that it be located at a target site not substantially affected by the laser procedure itself.
  • any natural eye feature located in proximity of and structurally contiguous to the target site can serve as the tracking landmark as long as it has enough contrast, a degree of symmetry and be capable of responding to forces and pressures in a manner similar to the targeted tissues, yet without being coincident with the precise target site itself, since this site will change during the course of the surgery.
  • the eye limbus at the radially outward edge of the cornea satisfies these constraints, providing sufficient contrast to allow the efficacious employment of the tracking methods discussed in this invention for a majority of the sighted patient population.
  • the limbus has the advantage of not only moving with the cornea — inasmuch as it is a part of the cornea — but, since it likewise is connected to the sclera, it will not respond as dramatically to the transient deformations associated with the microsurgery.
  • a method for tracking the limbus has been disclosed by Knopp et. al. in U.S patent application Serial No. 843,374 of which the present application is a continuation-in-part. This method employed a spatially sensitive sensor configuration comprising two quadrant detectors for which the limbus of the eye provided an ideally suited landmark.
  • the two quadrant detector configuration presents a large enough area to intercept the light reflected from the large extent of the limbus structure of relatively (about 12 mm in diameter for humans; more than 15 mm in rabbits) .
  • Figure 6 the method of detection used to track an image of the outer rim (at the limbus) of the iris as disclosed in the above mentioned patent application. This method is considered useful to one preferred embodiment of the present invention, applicable to ophthalmic surgical interventions, especially on or within the anterior segment of the eye, including the cornea.
  • the image at the two quadrant detectors consist of a bright lune-shaped field 33 corresponding to the sclera 2, adjacent to a darker field representing an image 32 of the iris 7.
  • the very dark central core which is an image 34 of the pupil 68, is not captured by the detectors, leaving a single sharp contrast boundary to track.
  • quadrant detectors integrate the image illumination striking each quadrant of the detector face, the photocurrents induced in the detector elements when normalized and subtracted according to the formulas shown in Figure 6, will permit computation of the position of the light spot with respect to the center of the detector configuration. A change in background light intensity will be ignored, as the increase across the or eight quadrants 35 of the detector face will remain the same. Voltage sums and differences among the quadrants therefore serve to establish the relative direction of motion between two contiguous readings of the limbus position. A shift in intensity at the sensor is thereby traced to motion of the limbus.
  • the two detector configuration affords substantial flexibility to operations within the anterior segment, including the option of activating only one sensor at a time corresponding to detection of one side of the limbus, while allowing simultaneous operations to be performed adjacent to the other corner of the iris.
  • the elliptical configuration of the illumination as shown in Figure 6 can be deliberately selected (using cylindrical lenses) as one method to increase the sensitivity along the Y direction.
  • physical obstructions such as the eye lid prevent the addition of two more quadrant detectors in a direction perpendicular to the first set thereby achieving full symmetry.
  • spherical images and hence imaging lenses may be used instead, as long as the light pattern is carefully tailored to heighten the sensitivity along the perpendicular (Y) direction.
  • a four quadrant detector configuration is an option that may be advantageously utilized in alternative embodiments for tracking other types of landmarks in applications that do not have the physical limitations imposed by the eye structure.
  • quadrant detectors are not the only type of sensors compatible with the more general methods disclosed herein.
  • the scope of the present invention is, in fact, broad enough to encompass a large number of possible targets and procedures and hence, a variety of tracking landmarks and detectors matched to sensing the contrasts thereof.
  • any feature possessing sufficient contrast can serve as a tracking landmark, as long as it also has a minimal degree of symmetry.
  • the pupil of the eye may also serve as a tracking mark.
  • the pupil may change its dimensions, since as long as the change is symmetrical and is not so fast as to exceed the response time of the sensors utilized, only relative illumination of different parts of the sensor(s) count in following the centroid of the illumination which is, in all cases, referenced to the center of the detectors' configuration.
  • using the pupil as a landmark is understood to fall within the domain of the present disclosure whenever pure contrast-based algorithms are utilized in the tracking.
  • tracking the pupil has certain advantages, such as when limited detection area (relative to the much larger limbus) is desired, when the limbus contrast is inadequate, or if precise balance between the two spatial dimensions to be tracked is crucial.
  • landmarks such as the optic disk, or vessel configurations (with suitably magnified views) can similarly provide landmarks upon which the present tracking method can be efficaciously deployed.
  • the primary modification required in choosing one particular feature to track upon over another involves selection of alternate sensor configurations and the associated algorithms.
  • the tracking sensors, or detectors, in combination with their circuitry should have fast response times and be capable of high spatial resolutions. This is because target tracking landmarks such as the limbus are often not a boundary but a transition zone (e.g., between the cornea and the sclera). Therefore, a tracking system which uses the location of the limbus or similar such feature must be able to filter out noise, recognize contrast, and accommodate for shapes that may appear to deform due to rotations.
  • PSD's position-sensing photodetectors
  • Examples of such advanced sensors are linear position sensing detectors and the quadrant detectors discussed above.
  • a position sensing detection system works by sensing the angular deflection (or linear - displacement) relative to a reference surface, or point, of a beam reflected off a moving element which is, in turn connected (optically) to the critically positioned target surface.
  • the basic set-up provides a signal proportional to the deflection error around a single axis normal to the axial direction (or, more generally to a given line of sight).
  • the polarity of the error indicates the direction of the error.
  • the addition of a second channel normal in orientation to the first allows correction of angular errors about either axis in a plane normal to the optical axis (or line of sight).
  • Quadrant detectors furnish a good example of a two-axis PSD.
  • four sensing elements are present on a single chip, which can therefore define position in two (X and Y) axes.
  • quadrant detectors With resolutions on the order of 0.1 microns and large detecting surfaces, quadrant detectors are highly suitable for precise centering and nulling and for position tracking of spatially extended features over narrow ranges.
  • similarly fast but more sensitive position sensing detectors may be used such as lateral-effect photodiodes, shown schematically in Figure 7. These may be especially useful in applications, such as in industrial processing where measurements over wider ranges are required.
  • This type of detector differs from the quadrant detector in that it comprises a single photodiode with continuous detection capability. This eliminates the "dead region" between the cells, and the signal outputs are directly proportional to the position of the centroid of light.
  • a two-axis lateral-effect diode acts as a pair of light-controlled variable resistors for measuring the position of a light spot on its X- and Y- coordinates, as illustrated by the equations in Figure 7.
  • this type of sensor provides good linearity over wider dynamic range than quadrant detector (within 3 % over the entire range, on the average), which renders them more suitable for certain type of applications requiring great accuracy, such as in diagnostics.
  • a linear position sensors such as the lateral-effect diode described here, may provide an excellent match for tracking alternative landmarks within the eye, such as the pupil, due to their smaller overall area and the greater demands placed upon sensor linearity (relative to e.g., the limbus).

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Abstract

Méthode, appareil et système de chirurgie de l'÷il et de micro-usinage industriel. Les caractéristiques originales du système de poursuite comportent des moyens pour (a) percevoir un contraste sous forme de limites à grande échelle facilement identifiables, tel qu'au niveau de l'interface cornée/sclérotique (limbus), et déterminer par là le positionnement absolu et l'orientation desdites limites sans recourir aux techniques d'échantillonnage numérique; (b) faire fonctionner en bimode un système électronique de contrôle compatible avec toutes les techniques analogiques et accroissant notablement la rapidité des opérations par rapport aux autres méthodes. Le système de poursuite de l'invention comprend au moins: une optique d'imagerie et sa source lumineuse (1), un capteur tel qu'un détecteur de position (31), un élément optique mobile tel qu'un miroir (9), un circuit logique bidimensionnel et un microprocesseur spécialisé (50) avec les microprogrammes et les logiciels appropriés de traitement des signaux. Une optique additionnelle peut servir d'interface avec d'autres équipements tels que des systèmes annexes de détection de profondeur, de visualisation des cibles et/ou de chirurgie laser.
PCT/US1994/002007 1993-02-19 1994-02-18 Systeme de compensation des mouvements lateraux d'une cible WO1994018883A1 (fr)

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EP0765648A2 (fr) * 1995-09-29 1997-04-02 Nidek Co., Ltd Appareil de chirurgie ophtalmique
EP0770370A2 (fr) * 1995-10-27 1997-05-02 IR Vision, Inc. Dispositif pour enlever du tissu cornéen par radiation laser à infrarouge
EP0821908A1 (fr) * 1996-08-01 1998-02-04 Sharp Kabushiki Kaisha Système de détection de l'oeil
EP0850614A2 (fr) * 1996-12-27 1998-07-01 Nidek Co., Ltd Dispositif pour la réalisation d'interventions ophtalmologiques
WO1999018868A1 (fr) 1997-10-10 1999-04-22 Visx Incorporated Detecteur de position oculaire pour chirurgie de l'oeil au laser, faisant appel a la detection de marge corneenne
WO1999023936A2 (fr) * 1997-11-11 1999-05-20 Irvision, Inc. Appareil de poursuite et de correction des mouvements de l'oeil et methode afferente
US5966197A (en) * 1998-04-21 1999-10-12 Visx, Incorporated Linear array eye tracker
EP0947183A3 (fr) * 1998-03-31 1999-12-08 Nidek Co., Ltd. Dispositif de traitement par laser
US6090102A (en) * 1997-05-12 2000-07-18 Irvision, Inc. Short pulse mid-infrared laser source for surgery
US6159202A (en) * 1995-09-29 2000-12-12 Nidex Co., Ltd. Corneal surgery apparatus
US6283954B1 (en) 1998-04-21 2001-09-04 Visx, Incorporated Linear array eye tracker
US6322216B1 (en) 1999-10-07 2001-11-27 Visx, Inc Two camera off-axis eye tracker for laser eye surgery
AU2003204087B2 (en) * 1995-10-27 2005-02-03 Visx, Incorporated Method and Apparatus For Removing Corneal Tissue With Infrared Laser Radiation
WO2005065527A1 (fr) * 2004-01-09 2005-07-21 Customvis Plc Poursuite oculaire par localisation limbique
EP1981426A2 (fr) * 2006-01-20 2008-10-22 Lensar, Inc. Système et appareil permettant d'administrer un faisceau laser dans le cristallin d'un oeil
US7458683B2 (en) 2003-06-16 2008-12-02 Amo Manufacturing Usa, Llc Methods and devices for registering optical measurement datasets of an optical system
DE10297574B4 (de) * 2001-12-21 2009-09-10 Sensomotoric Instruments Gmbh Verfahren und Vorrichtung zur Augenerfassung
US8556885B2 (en) 1999-10-21 2013-10-15 Bausch & Lomb Incorporated Iris recognition and tracking for optical treatment
WO2014066671A1 (fr) * 2012-10-24 2014-05-01 Amo Development, Llc. Système de lentille de balayage et procédés de réduction des forces de réaction en son sein
US8740385B2 (en) 2002-05-30 2014-06-03 Amo Manufacturing Usa, Llc Methods and systems for tracking a torsional orientation and position of an eye
US9117149B2 (en) 2011-10-07 2015-08-25 Industrial Technology Research Institute Optical registration carrier
CN110191320A (zh) * 2019-05-29 2019-08-30 合肥学院 基于像素时序运动分析的视频抖动与冻结检测方法及装置
US10514553B2 (en) 2015-06-30 2019-12-24 3M Innovative Properties Company Polarizing beam splitting system
WO2020157746A1 (fr) 2019-01-29 2020-08-06 Eyeway Vision Ltd. Dispositif de suivi oculaire et procédé associé

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US4443075A (en) * 1981-06-26 1984-04-17 Sri International Stabilized visual system
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Cited By (50)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6491687B1 (en) 1995-09-29 2002-12-10 Nidek Co., Ltd. Corneal Surgery apparatus
EP0765648A2 (fr) * 1995-09-29 1997-04-02 Nidek Co., Ltd Appareil de chirurgie ophtalmique
US6986765B2 (en) 1995-09-29 2006-01-17 Nidek Co., Ltd. Corneal surgery apparatus
EP0765648A3 (fr) * 1995-09-29 1998-09-23 Nidek Co., Ltd Appareil de chirurgie ophtalmique
US6159202A (en) * 1995-09-29 2000-12-12 Nidex Co., Ltd. Corneal surgery apparatus
EP0770370A3 (fr) * 1995-10-27 1997-07-02 Ir Vision Inc Dispositif pour enlever du tissu cornéen par radiation laser à infrarouge
US5782822A (en) * 1995-10-27 1998-07-21 Ir Vision, Inc. Method and apparatus for removing corneal tissue with infrared laser radiation
EP0770370A2 (fr) * 1995-10-27 1997-05-02 IR Vision, Inc. Dispositif pour enlever du tissu cornéen par radiation laser à infrarouge
AU2003204087B2 (en) * 1995-10-27 2005-02-03 Visx, Incorporated Method and Apparatus For Removing Corneal Tissue With Infrared Laser Radiation
JP2006320749A (ja) * 1995-10-27 2006-11-30 Visx Inc 赤外線レーザー放射を用いる角膜組織除去法及びその装置
EP0821908A1 (fr) * 1996-08-01 1998-02-04 Sharp Kabushiki Kaisha Système de détection de l'oeil
US5861940A (en) * 1996-08-01 1999-01-19 Sharp Kabushiki Kaisha Eye detection system for providing eye gaze tracking
EP0850614A2 (fr) * 1996-12-27 1998-07-01 Nidek Co., Ltd Dispositif pour la réalisation d'interventions ophtalmologiques
EP0850614A3 (fr) * 1996-12-27 1999-03-10 Nidek Co., Ltd Dispositif pour la réalisation d'interventions ophtalmologiques
US6090102A (en) * 1997-05-12 2000-07-18 Irvision, Inc. Short pulse mid-infrared laser source for surgery
EP1026998A1 (fr) * 1997-10-10 2000-08-16 Visx Incorporated Detecteur de position oculaire pour chirurgie de l'oeil au laser, faisant appel a la detection de marge corneenne
EP1026998A4 (fr) * 1997-10-10 2002-08-21 Visx Inc Detecteur de position oculaire pour chirurgie de l'oeil au laser, faisant appel a la detection de marge corneenne
WO1999018868A1 (fr) 1997-10-10 1999-04-22 Visx Incorporated Detecteur de position oculaire pour chirurgie de l'oeil au laser, faisant appel a la detection de marge corneenne
US6299307B1 (en) 1997-10-10 2001-10-09 Visx, Incorporated Eye tracking device for laser eye surgery using corneal margin detection
WO1999023936A3 (fr) * 1997-11-11 1999-12-09 Irvision Inc Appareil de poursuite et de correction des mouvements de l'oeil et methode afferente
WO1999023936A2 (fr) * 1997-11-11 1999-05-20 Irvision, Inc. Appareil de poursuite et de correction des mouvements de l'oeil et methode afferente
EP0947183A3 (fr) * 1998-03-31 1999-12-08 Nidek Co., Ltd. Dispositif de traitement par laser
US6235014B1 (en) 1998-03-31 2001-05-22 Nidek Co., Ltd. Laser treatment apparatus
US5966197A (en) * 1998-04-21 1999-10-12 Visx, Incorporated Linear array eye tracker
US6283954B1 (en) 1998-04-21 2001-09-04 Visx, Incorporated Linear array eye tracker
EP1080390A4 (fr) * 1998-04-21 2002-05-22 Visx Inc Oculometre a barrette
EP1080390A1 (fr) * 1998-04-21 2001-03-07 Visx Incorporated Oculometre a barrette
US6322216B1 (en) 1999-10-07 2001-11-27 Visx, Inc Two camera off-axis eye tracker for laser eye surgery
JP2003517354A (ja) * 1999-10-07 2003-05-27 ヴィスクス インコーポレイテッド 二つのカメラ軸外し目追尾装置
US8556885B2 (en) 1999-10-21 2013-10-15 Bausch & Lomb Incorporated Iris recognition and tracking for optical treatment
DE10297574B4 (de) * 2001-12-21 2009-09-10 Sensomotoric Instruments Gmbh Verfahren und Vorrichtung zur Augenerfassung
US9596983B2 (en) 2002-05-30 2017-03-21 Amo Manufacturing Usa, Llc Methods and systems for tracking a torsional orientation and position of an eye
US10251783B2 (en) 2002-05-30 2019-04-09 Amo Manufacturing Usa, Llc Methods and systems for tracking a torsional orientation and position of an eye
US8740385B2 (en) 2002-05-30 2014-06-03 Amo Manufacturing Usa, Llc Methods and systems for tracking a torsional orientation and position of an eye
US7458683B2 (en) 2003-06-16 2008-12-02 Amo Manufacturing Usa, Llc Methods and devices for registering optical measurement datasets of an optical system
GB2426816B (en) * 2004-01-09 2007-06-20 Customvis Plc Limbal-based eye tracking
US7682023B2 (en) 2004-01-09 2010-03-23 Customvis Plc Limbal-based eye tracking
WO2005065527A1 (fr) * 2004-01-09 2005-07-21 Customvis Plc Poursuite oculaire par localisation limbique
GB2426816A (en) * 2004-01-09 2006-12-06 Customvis Plc Limbal-based eye tracking
EP1981426A2 (fr) * 2006-01-20 2008-10-22 Lensar, Inc. Système et appareil permettant d'administrer un faisceau laser dans le cristallin d'un oeil
EP1981426A4 (fr) * 2006-01-20 2015-03-11 Lensar Inc Système et appareil permettant d'administrer un faisceau laser dans le cristallin d'un oeil
US9117149B2 (en) 2011-10-07 2015-08-25 Industrial Technology Research Institute Optical registration carrier
US9158084B2 (en) 2012-10-24 2015-10-13 Amo Development, Llc Scanning lens systems and methods of reducing reaction forces therein
WO2014066671A1 (fr) * 2012-10-24 2014-05-01 Amo Development, Llc. Système de lentille de balayage et procédés de réduction des forces de réaction en son sein
US10514553B2 (en) 2015-06-30 2019-12-24 3M Innovative Properties Company Polarizing beam splitting system
US11061233B2 (en) 2015-06-30 2021-07-13 3M Innovative Properties Company Polarizing beam splitter and illuminator including same
US11693243B2 (en) 2015-06-30 2023-07-04 3M Innovative Properties Company Polarizing beam splitting system
WO2020157746A1 (fr) 2019-01-29 2020-08-06 Eyeway Vision Ltd. Dispositif de suivi oculaire et procédé associé
CN110191320A (zh) * 2019-05-29 2019-08-30 合肥学院 基于像素时序运动分析的视频抖动与冻结检测方法及装置
CN110191320B (zh) * 2019-05-29 2021-03-16 合肥学院 基于像素时序运动分析的视频抖动与冻结检测方法及装置

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AU6249694A (en) 1994-09-14
IL108672A (en) 1997-07-13

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