DE1963450A1 - METHOD AND DEVICE FOR AUTOMATIC MEASUREMENT OF THE DIRECTION OF THE OPTICAL AXIS OF THE HUMAN EYE - Google Patents

Description

Patent application

Applicant: Alain Georges ORSZAG, ORSAY (France)

Method and device for automatically measuring the direction of the optical axis of the human eye.

The invention relates to methods and apparatus for automatic Measurement of the direction of the optical axis of the human eye.

When looking at an object in daylight, the movements of the eye are known to have the effect that Image of the viewed object on a small zone of the retinal skin, the so-called Porea, where the cast light-sensitive elements of the retina especially dioht are arranged so that the part of the eye is at its maximum Has resolving power under the optical or eye axis in the following the direction is understood, welshe the center of the eye lens connects with the center of the foT © a.

Likewise, numerous experiments have shown that the observation a solid mark on the side of the eye of one

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CONSTRUCTION ORIGINAL

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the German Patent Office, Munich 1963450

slow drift (one to two arc minutes per second) the straightening of the achae is accompanied. This drift is compensated for by a sudden movement that returns the eye axis to the observed object as soon as the angular distance between the eye axis increases and the ideal line of sight reached a few minutes of arc.

The direct measurement of the direction of the axis of the eyeball can aleο exactly to about five minutes of arc Specify the direction of the observed object while integrating the eye movements during a sufficient α long time period (greater than two to three seconds) a © would enable more precise directional determination.

The invention proposes several methods and devices to determine the sighting of the axis of the eye directed at a given object.

The basic idea of the invention is therefore to automatically Measure the direction of the optical axis of the human eye using a light source to create an image in the eye or to reflect on it and measure the direction of emergence of the image bu or with the direction of incidence of the. light to compare.

Various methods are available for implementation, the different with regard to the »measuring devices required for them are expensive.

According to a first method, flexion-making is carried out one falling on a mirror © placed on the eyeball Light beam measured, with the direction of a = » -falling light beam feat is or with ΗΙΙΓβ one after guide device with the direction of the reflected light ray, is kept under cover.

BATH ORIGINAL

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German Patent Office, Munich T9? 3450 Potenkmwdt

After a second procedure, the cornea falls asleep Eye designed an image, the image of which is measured as in the first method, but only with this combined with the result of an orientation of the head Measurement result for the position of the eye axis with respect to a stationary one Brand leads. '.

A third method involves designing from a light source Illuminated with invisible light! Tetshaut through the lens of the eye an image in infinity, its position by comparing characteristic image details or by Comparison of the entire image in an optical correlator indicating the direction of the eye axis Light source can be shifted depending on the position of the eye in such a way that the most sensitive zones of the Retina not illuminated. The Invisible fluorescence radiation from the retina excited by the light source is used as an image. - A special The advantage of this method is that the observing person does not have any equipment or facilities must carry.

To carry out the first-mentioned method, a device is used in which a preferably circular ring Facet-bearing contact glass placed on the eye and an optical measuring device in the incident beam path, a light source, a collimator and a normally transparent mirror and in the failing one Beam path has a lens and a television camera. Collimator and lens can be combined to form lens or mirror optics, and in front of the eye can a second semitransparent mirror connected to the optical measuring device is arranged around the Arrange optical measuring device to the side of the eye can.

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German Patent Office, Munich 1963450

In a simpler variant, instead of the TV camera, two detectors controlled by tracking devices can also be provided, and in a further modification the light source can have two additional detectors Tracking devices are tracked in such a way that Always cover incoming and outgoing light beams. Filters can be arranged behind the light source which, for example, block out all or part of the visible light.

To carry out the method mentioned in the second place, a device is proposed in which is incident Beam path a light source, a first semitransparent mirror, an optical system and a second semitransparent mirror Mirror in front of the eye and in the failing Beam path behind the second semitransparent mirror again a television camera or two through tracking devices Controlled detectors are combined in an optical measuring device, which is firmly attached to a helmet that is worn by the observer. Of the Helmet can be fixed via cardanic rods Be connected to angle sensors or carry a mirror, the position of a fixed optical measuring device is measured. ■

To carry out the third method, a device is proposed in which a movable opening is provided in the focal plane of the lens behind a second semitransparent mirror, in front of which a light source, an objective and a first semitransparent mirror located in front of the eye are arranged © represents a characteristic Bildeinzellieit the illuminated retina and lying behind it with ,, paired detectors is ^connected%, -the / kr an ice topped up for the movable aperture control * In

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5 ".ΡβρΜ» β. Β. I & Uabe

German Patent Office, Munich

this can be done in the focal plane defö objectives In an optical correlator, a positive image of the $ ileea of the illuminated retina be arranged so that a point of light in the focal plane of the! Correlator die Specifying sighting of the Aagenaehse. In a further modification can the positive recording movable and with A lead arrangement for equality of the be connected to both images, so that the position of the positive image indicates the direction of the eye aohae.

The invention can be evaluated, for example, for the delivery of actuating signals for servo controls and steering of devices ₈ which are aimed at by an observer as a target and see relatively moving therefrom.

To explain the invention, some are given below Implementation example © described on the basis of the drawing; in these show in »! thematic positions:

Pig. 1-, AnorÄnungen of devices for carrying ^D tion of a first measurement method according to the Erfindungι

TtIg, 4 an arrangement of gate directions for carrying out a second measuring method according to the! Invention!

Pig. 5 shows an arrangement of preparations for carrying out f implementation of a third measurement method the load and

? ig. 6 is a sp®zi®lle Ausführungsforjn the "In Pig _1, the measuring means shown.

Bai am the first method * according to the invention (Pi'g _e 1) sits on the eye! a neutral®® contact lens TO ^, in which a flat - Racett M is incorporated »di @ to the optical axis of the eye: and die

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German Patent Office, Munich '^ "^^^^ Patent Attorney

fiolle of a mirror. (The third facet "is located outside the zone through which the rays of light traverse the image of the object being viewed design on the retina. The facet can have the shape of a flat circular ring, it can be in the same way Formed by a disc, which is cemented to the contact glass on its front.)

Since light from a light source S, which may be filtered by filter F to suppress the visible component, is thrown with the help of a collimator C in Poeü of a parallel beam via a semi-transparent mirror A onto the facet II. After the reflection at M, the still parallel bundle of rays is recorded by an optical device O, which ^{creates the image S 1} of S in a focal plane. If one knows the position of this image, one can find the direction of the perpendicular to the facet M, which is parallel to the optical axis of the eye, given the position of S.

The collimator C and the lens 0 can be used as a unit be formed and with the light source S one Auto collimator (Fig. 2) form. 0 can be act a lens object. A mirror optic (with spherical or paratolian mirrors) can also be used. can be used, which have larger openings Achieving lower cost and weight is allowed.

The orientation of; 3 'can entwe'le? Bit X is used by several detectors Dj, Dp ·· * Ί). .? £ ri (Fig 21 3rfo _!!;. The 'be nachgefülirt and cl-ph y Ia ^ e mixture. · Is or Giner with ItLIf e Fernsehkt-ra' the picture TV 3 (F ;:, τ "j ) cd er through, any similar device.

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Deutr, ehe Patent Office, Munich patent attorney

In another measuring device (Pig. 3) the light source S eats in a movable manner, and a servomechanism constantly adjusts it so that S ¹ remains in a constant position. The measured optical axis then passes through the point S. This embodiment has the advantage that the optical dimensions are reduced. With it, however, a second semi-transparent mirror L must be provided in order to arrange the optical measuring arrangement to the side so that the observer has a sufficient field of view. This arrangement with a semitransparent mirror can be used in the same way with a fixed light source 3 in order to leave the observer greater freedom of movement.

In general, the optical axis with respect to that of the light source S, objective 0, collimator C and detectors D is determined composite unit formed. It suffices if this Parts - and also the second semitransparent ßpiegel L, if it is present - are fixed to each other are so that the direction of the optical axis of the eye3 is absolutely known regardless of which movements the observer executes with his head.

In the second method, according to the invention, one uses the HorrJiautreflexion, i.e. the reflection from the front of the eyeball in order from a light source S, possibly filtered and equipped with a condenser C. is to design a first image S ^ * (Pig. 4). This 3ild is then aui'genor: imen through a lens 0, which - delivers an image 3 'in its focal plane. In this Focal plane is a Kesssysten that one of the both of the Messayöt.eme already described in the: -ara ten 'procedure and that allows the position of S 'to be determined. The knowledge of 3 'is only sufficient to determine the best the direction of the Aufjeticichüe nu.s, if that

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German Patent Office, Munich * ° Patent attorney

Center of the eye3 no shift in relation to the objective 0 experiences because with the cornea's radius of curvature of approx. 8 mm it is impossible to have both images S and 3 « can stand on infinity.

If one takes into account that the center of rotation _{# of} the eye3 is close to the center of curvature of the cornea, then a rotation of the eye can only bring about ^{a small falling shift between S and ü 1.} The shift, however, is superimposed on any shift of the center point with respect to the optical measuring device formed from optics and detectors. To do this, the measuring device must be firmly connected to the head of the observer, the light source S, objective 0 and detector TV are assembled as closely as possible with a bent beam path in order to keep space requirements and the moment of inertia as small as possible. The measuring device is located on a specially designed helmet M. With regard to this helmet, the angles X ₁ and V ₁ indicate the orientation of the eye.

If the optical axis of the eye with respect to the head of the observer has been determined in this way, then knowledge of the head position with respect to a fixed mark is also required. It can be obtained in a number of ways. In the case of an optical determination according to the first method, the helmet H wears a mirror VL (FIG. 4); in the case of a mechanical determination of the head position, it is connected to fixed angle sensors via a cardanic linkage.

In each case three ¥ in> el O ₁ , f ^ , y ^ are measured, which indicate the spatial direction of the helmet H with respect to a fixed mark. The final knowledge of the

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German Patent Office, MUnohen Potent «* ·« *

Direction of the optical eye socket requires that of to combine the information provided by the two systems described. A computer is required for this, whereby however, it can be a simple analog computer, since only a change of coordinates and an addition are required are.

In a third method (Pig. 5) the optical properties of the eye itself are exploited by using it as a collimator which has the retina R as a light source, from which the eye lens Cr, which acts as an objective, creates an image at infinity. For this purpose, the retina is externally through an auxiliary light source.S with the help of a condenser C and with the help of filters]? enlightened. The task of the tilter is to prevent siolibar radiation from reaching the retina, which could partially dazzle the observer.

The image of the retinal skin, which is projected to infinity by the lens of the eye, is recorded by the objective 0, since an image R ¹ of E is created in its focal plane *. The position of R ¹ and, more precisely, of the image of the fovea directly provides the direction of the eye axis as in the first method.

However, the automatic read sung the position of the fovea iet much harder durchsufuhren ale that because the image R ¹ has a Liohtpunktes a very small contrast. The most recognizable elements of this picture are images of blood vessels in the retina. For the determination of the position of R. ^{1, it} is therefore intended either to use a group of such vessels or to use the entire image R ^f .

In a first embodiment of the associated device (Jig · 5a) becomes the image in a zone with strong

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German Patent Office, Munich

Contrast (vascular branching or nodes, etc.) ^{imaged on a movable opening m 1 of the} same type of fora. Behind the opening ro ', detectors D ₁ , D ₂ * ^D 3 » ^D , i are fixedly connected to it and arranged in pairs: They supply error voltages which, after being amplified, serve to constantly track m' to the selected zone, including tracking devices as in Fig. 2 or 3 can be used. In this case, the position of m ¹ provides the direction of the optical axis of the eye.

In a second embodiment of the device (Fig. 5b), the image R *, which is possibly amplified by a brilliance amplifier AB or by a television recording device, is compared with a photograph P, the transparency of which is a linear function of the at each point Illuminance of the corresponding point of R ¹ is. (P can be prepared directly from R ¹ by positive photography if a suitable contrast emulsion is used.) R ¹ is then compared to P, preferably optically, in order to obtain a compact and sufficiently inexpensive device. The result of the comparison appears as a point I in the focal plane of the object of the correlator Go used. The position of the point I ″ indicates the shift between R 'and P ¹ and thus the direction of the achae of the eyes.

In a modified form of this comparison, the positive receptacle P is movable and is tracked in such a way that it constantly overlaps with the image R ¹ . In this case, the position of P indicates the direction of the eye axis.

In an improved method, the auxiliary light source R can depending on the measured position of the,

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German Patent Office, Munich '' ^ ° ^J * »^ ^U P ° tentonwoit

Of the eye, for example, to illuminate the avoid the most sensitive areas of the retina. Just the most sensitive areas of the retina supply due to their weak contrast does not make a decisive contribution for measuring the direction of the eyes. If the method is further improved, the fluorescence properties exploited some special areas of the retina. These zones deliver when they are from an auxiliary light source are excited, a radiation of greater wavelength, which is used to determine the optical axis of the eye can be used because the radiation can provide a special image R *. .

Of course e3 is required that the excitationa radiation as well as fluorescence radiation in the invisible Area, but still transmitted well by the inner media of the eye and properly bundled by the eye will.

Pig shows a possible practical embodiment of the device shown schematically in FIG. 5b. 6. If, however, as proposed, the brilliance amplifier is replaced by a television recording / playback device, then only the camera is ^{arranged behind R 1} , and the playback device and the comparator can be arranged at some distance.

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Claims (16)

Claims fil Procedure for automatically measuring the direction of the optical axis of the human eye, characterized in that with the aid of a light source a Image generated in the eye or mirrored to it and measured the direction of the image or with the Direction of incidence of the light is compared. 2. The method according to claim 1, characterized in that the direction of reflection on one of the eyeball mounted mirror (M) incident light beam is measured, with the direction of the incident Light beam is fixed or with the help of a tracking device with the direction of the reflected light beam is kept under cover. 3. The method according to claim 1, characterized in that an image (S ₁ ) is designed on the cornea of the eye, the air formation (S ¹ ) is measured as in the method according to claim 2, and that the Ifeas result (x-jy-j ), combined with the result (^ / - ji ^ -j) of a determination of the position of the head, which supplies the position (xy) of the eye axis with respect to a stationary mark. 4. The method according to claim 1, characterized in that the retina (R) illuminated by a light source (S) with invisible light creates an image at infinity via the eye lens, the position of which by comparing characteristic image details (m) or by comparing the whole Image (R ¹ P) in an optical correlator (Go) indicates the direction of the eye axis. 3 0 9809/000 8 BATH ORIGINAL German pat entrant, Munich ' ^{a DJ} ^ ^DU Pat.ntanwoh 5. The method according to claim 4, characterized in that the excited by the light source (S) does not see "bare Fluorescence beamunp; the retina is used as an image 6. Device for carrying out the method according to claim 2, characterized by a preferably a circular ring-shaped pacette (L ') carrying, on da.3. ^ Uje placed contact glass (VO) and by an optical measuring device that a light source (S ), a collimator (0) and a semi-transparent mirror (A) and an objective (0) and a television camera (I ¹ V) in the emerging beam path. 7. Apparatus according to claim 6, characterized in that the collimator (G) and lens (0) to a lens or mirror optics are zuaanmengefaeet. 8. Apparatus according to claim 6 upper 7 »marked thereby net that in front of the eye a second semi-transparent mirror connected to the optical measuring device " (1) is arranged. 9. The device according to one or more of claims 6 to 8, characterized in that instead of the television camera two duroh tracking devices controlled detectors (D ₁ , D ₂ ) are arranged. 10. Apparatus according to claim 8 and 9, characterized by two further tracking devices which the Near the light source (S) in such a way that the incident and emergent light beam constantly coincide. 11. The device for performing the Verfaiirens according to claim 3 »characterized in that in the incident 309809/000 4 Q λ -j / c pjIMpl.-Ιηβ. β. SdilUb « German Patent Office, Munich. ^Pa ** ^nfqnwoft ' Beam path a light source (S), a first semitransparent mirror (A), optics (0) and a second semitransparent mirror (L) in front of the eye and in the failing beam path behind the first semitransparent mirror a television camera (IV) or two controlled by guide devices detectors (D., D ₂₎ ^iR are summarized optiochen a measuring device which is rigidly connected to a worn by the observer helmet (H). 12. The device according to claim 11, characterized in that that the helmet is fixed in place via cardanic rods Angle encoders is connected. 13. The device according to claim 11, characterized in that that a mirror (Ej) is attached to the helmet and a fixed optical one for determining the mirror position Measuring device provided iat. H. Device for carrying out the method according to claim 4, characterized in that behind a second semi-permeable mirror, in front of which a light source (S), an objective (O) and a first semi-permeable mirror (L) located in front of the eye are arranged, A movable opening (m ') is provided in the focal plane of the lens, which reproduces a characteristic image detail (m) of the illuminated retina and connects the detectors (D ^, Do, B- ,, D ^) lying behind it that control a tracking circuit for the movable opening (m ¹ ). 15. Device for performing the method according to spoke 4, characterized in that in the focal plane of the lens in an optical correlate! "(Go) 309809/000 BATH ORIGINAL German Patent Office, Munich a tranparent positive image (P) of the image (R ') the illuminated retina is arranged so that a light point (I) in the focal plane of the correlator Indicating the direction of the eye axis. 16. The device according to claim 15 »characterized in that the positive receptacle (P) is movable and connected to a tracking device for ^{congruence of the images (P) and (R 1} ), so that the position of (P) indicates the direction of the eye axis. _: 309809/0008