WO1984003430A1

WO1984003430A1 - Skiascopy apparatus

Info

Publication number: WO1984003430A1
Application number: PCT/AT1984/000008
Authority: WO
Inventors: Wolfdietrich Steinhuber
Original assignee: Wolfdietrich Steinhuber
Priority date: 1983-03-01
Filing date: 1984-02-20
Publication date: 1984-09-13
Also published as: DE3307168C2; DE3307168A1; EP0136305A1; ATA902184A

Abstract

A skiascope provided with a lighting device (8) and a skiascopy mirror (3) is connected on the examiner side to an optical system (17). The optical system is provided with a first converging lens device (4) and with a diaphragm (5) of which the opening width is preferably adjustable. The converging lens device is positioned with a certain interval from the far point (F) of the emmetropic (possibly ametropic eye) (1), interval which is equal to once to twice the focal distance (f1) of the first converging lens device (4). Between the diaphragm (5) and the first converging lens device (4) there is provided on the examiner side a second interval or distance larger than the double of the focal distance (f1) so that the diaphragm (5) appears smaller at the far point (F). To the diaphragm (5), there is connected on the examiner side an inversion lens system (6) spaced from the diaphragm (5) by the smallest possible interval. To the first converging lens device (4), respectively to the inversion lens system (6), a second converging lens device (7) used as an ocular is conveniently connected on the examiner side. The interval between the second converging lens device and its real intermediary image (B1, respectively B2) is equal to its focal distance (f3).

Description

Device for scoping

The invention relates to a device for skiascopy with an illumination device and a skiascope mirror, to which an aperture is connected on the examiner side.

With the help of such a device - a skiascope 5 _. - The objective determination of the refractive condition of an eye can be determined without the test specimen being said. In this case, the far point is the eye by means of suitable Vorsatzlin¬ sen in a practical for the examiner distance moved, and the retinoscope so arranged that the aperture plane passing through the point at infinity, then the ^'refraction of about prü¬ fenden eye is due to the respective illumination his Determined pill. The approximately parallel beam of light deflected by the illuminating device via the retinoscope mirror is directed onto the eye to be examined and is slowly moved so that it runs across the pupil. If the eye to be examined is normal-sighted, the moving light bundle, which is observed in the direction of incidence through the diaphragm, brings about a sharp and uniform illumination of the pupil to be examined, ie an abrupt change between darkness and complete illumination. If the eye to be examined is defective, the transition between darkness and complete illumination of the pupil does not begin immediately, but a migration of the light / dark boundary can be observed. This hike is opposite in the case of a short-sighted eye, in the case of a far-sighted eye it follows the movement of the light beam.

It is known that the accuracy of measurement increases with increasing distance of the skiascope from the eye to be examined, although the reading is made more difficult. In practice, this results in a minimum distance of about 50 cm, which can hardly be undercut, and a maximum bs and of about 100 cm. To be annoying now. If possible to switch off influences of various types, skiascopes are provided with an aperture with a small opening width. This diaphragm can be formed, for example, by a bore in the ski retractable mirror or by a separate diaphragm if a partially permeable ski copy mirror is used. Here too, an compromise is necessary, since on the one hand the disturbing influences are reduced, the smaller the diameter of the diaphragm, but on the other hand there are observation difficulties due to the edge of the diaphragm opening. For a sufficient accuracy of the measurement result, a bore diameter of less than 0.7 mm would be necessary, for example in the case of pierced mirrors. Another reason for the reduction of the diaphragm diameter lies in the irregularities of the eye to be examined itself. It occurs relatively frequently that different refraction conditions occur on the eye to be examined. Therefore, a beam of observation rays occurs through a larger diaphragm Larger diameter through the diaphragm, irregularities in the eye to be examined can mean that opposite movements of the light / dark boundary occur simultaneously in different partial areas, so that the type or the predominant portion of the ametropia is scarcely is noticeable. Here, too, a reduction in the diaphragm diameter leads to an essentially exact statement, since this reduces the radius of the observation beam and thus observes the central region, which is regarded as dominant in these cases, and its ametropia for the assessment of the correction is more precise can be attracted here. So far, there have been various attempts to solve these problems. For example, it has become known to place a telescope between the eye to be tested and the ski ascora. A slightly magnifying, Galilean telescope is used as the telescope. Since the pupil of the eye to be examined appears enlarged, a small central section of the observation beam passes through the diaphragm of the retinoscope. However, it is disadvantageous that the illuminating beam must also pass through the telescope. There are therefore different examination conditions than with a mere reduction of the aperture with the illumination beam unchanged.

The invention has now set itself the task of a To improve the device for skiascopy so that it has a reduced aperture opening width and the non-central ring area of the observation beam can be masked out without disturbing side effects such as diffraction phenomena at the edge of the 5 aperture opening.

According to the invention, this object is now achieved in that a first converging lens arrangement is provided at a first distance from the distant point of the normal-sighted, possibly corrected eye, which lies between the single and 10, double the focal length of the first converging lens arrangement, and in that the diaphragm on the examiner side a second distance from the first converging lens arrangement which is dependent on the first distance and which is greater than the double focal length thereof, the aperture being reduced in the far point.

- _j _5 which will point in the inventive proposal Fern¬ By substantially parallel incident BeobachtungsStrah¬ lenbündel through the first converging lens arrangement bundled and it is formed under the viewfinder side in the distance of the simple focal length of the lens assembly is an inverted, real

20 Z \ / _ ε.chenbild. The aperture, the opening width of which can preferably be changed, is in turn reduced in size as an image diaphragm due to its distance lying above the double focal length of the converging lens arrangement on the side of the converging lens arrangement facing the eye to be examined. The image diaphragm which has been moved to the far point in this way does not bring about any diffraction phenomena and can therefore have a much smaller opening width than physical diaphragms. If, for example, a first magnifying lens arrangement is used, which magnifies ten times, an examiner aperture 0 with a 3 mm opening width is imaged in the far point as an image aperture with an opening width of 0.3 mm. Since, on the one hand, the first converging lens arrangement can have any magnification and, on the other hand, the aperture can preferably be adjusted in its opening width, 5 '' image apertures of any size can be achieved.

^ gJRE OMPI In a preferred embodiment it is provided that the distance between the first converging lens arrangement and the far point of the eye can be varied to an extent between the single and double the focal length of the first converging lens arrangement, so that the size of the first intermediate image can be adapted to the respective examination conditions. If it is also provided that the distance of the diaphragm from the first intermediate image of the first converging lens arrangement can be changed, which results in an axial displacement of the image diaphragm, the stationary device according to the invention is also suitable for carrying out the so-called unstable skiascope method, which is used in the There is observation of the changeover point between the direction of travel of the light / dark boundary when the examination distance changes.

As mentioned, the resulting first intermediate image is reversed, so that the direction of travel of the light / dark boundary is opposite to that of conventional ski ascopes. For direct examination by the examiner, however, it is expedient to reverse the wrong intermediate image, for which purpose a reversing lens system is placed in front of the examiner, the distance from the diaphragm being as small as possible. The smaller the distance between the reversing lens system and the diaphragm, the larger the area of the inverted intermediate image that can be detected by the reversing lens system, so that the light loss is as small as possible. The diaphragm can therefore also be provided in the reversing lens system. The reversing lens system now creates an upright real second intermediate image.

Direct examination of the examiner is further facilitated if the diaphragm or, in particular, the reversing lens system is placed in front of the examiner on the side of a second converging lens arrangement whose distance from the first, wrong intermediate image or the second, upright intermediate image is equal to the simple focal length of the second converging lens arrangement is. This second collecting lens arrangement forming the eyepiece therefore forms a magnifying glass for enlarged viewing of the intermediate image. The device according to the invention enables a further reduction in the investigator distance by projecting a very small image aperture into the far point with a corresponding shortening of the far point distance from the eye to be examined, without significantly influencing the measuring accuracy. The device according to the invention can therefore also be designed as an additive to a phoropter and fixed thereon by means of a suitable holder.

The invention will now be described in more detail below with reference to the drawings accompanying the drawings, without being restricted thereto. Fig. 1 shows a schematic longitudinal section through a device according to the invention, and Fi 2 is an enlarged view of the observation beam path

- The device according to the invention for skiascoping knows a simple skiascope, which is housed in a housing 16. At 45 to the optical axis A, a Skiasko pier mirror 3 is provided, which is preferably partially permeable, but may also have a central opening with respect to the axis A. The illuminating beam emitted by a schematically illustrated illuminating device 8 falls on the retinoscope mirror and, essentially deflected coaxially to the optical axis A, falls on the eye 1 to be examined. The skiascopy mirror 3 shown embodiment consists of several narrow isosceles triangular mirror surfaces, which with their tips a form the side surface of a polygonal pyramid. The retinoscope mirror 3 is rotatably mounted about the axis 10 passing through the spit and can be driven by a motor 9 which can be switched in both directions of rotation. As a result, movement of the illuminating beam bundle qu over the pupil of the eye 1 to be examined is achieved. An optical system 17 extends coaxially to the optical axis A and is described in more detail below. The tube 18 of the optical system 17 is rotatably mounted on a Hal tion 12, the bearing 11 being assigned a scale with graduation. The bracket 12 is with

OMPI provided a handle 15 on which the device for hands-free examination can be held. However, the handle 15 can also be replaced by a stand or a frame. Furthermore, the holder 12, as shown in dashed lines, can be provided with a support arm 19 which is attached to a schematically indicated phoropter 13.

The distance of the far point F of the eye 1 to be examined is reduced to a practicable examination distance by means of one or more attachment lenses 14. In the embodiment shown, the far point F therefore lies approximately at the intersection of the retinoscope mirror 3 with the optical axis A. As can be seen from FIG. 2, the optical system 17 has a first converging lens arrangement 4, which is at a distance from the far point F lies between the single and double focal length f .. the first converging lens arrangement 4. This first converging lens arrangement 4 generates a first real inverted intermediate image β which, since the observation beam strikes the converging lens arrangement 4 approximately in parallel, lies essentially in the focal point of the converging lens arrangement 4 on the examiner side.

A diaphragm 5, which can be changed in particular in the opening width, is placed on the examiner side of the first converging lens arrangement 4, its distance from the first converging lens arrangement 4 being greater than its double focal length f ₁ . This second distance is selected as a function of the first distance of the converging lens arrangement 4 from the far point F so that the aperture 5 is reduced in size as an image aperture 20 at the far point F. The observation beam bundle striking the examiner eye 2 is therefore narrowed by the image diaphragm 20, the projected opening edge of which naturally does not cause diffraction phenomena, and not by a physical diaphragm. The opening width of the image diaphragm 20 can therefore be kept very small. The converging lens arrangement 4 and the diaphragm 5 can optionally be displaced in the longitudinal direction of the axis A, whereby on the one hand also the unstable skiascopy method is used and on the other hand the reduction factor of the image diaphragm 20

(OMPI can be chosen. As close as possible to the diaphragm 5 is a reversing lens system 6, which forms an upright second intermediate image B _? generated. The upright, second intermediate image B_ now appears to the examiner eye 2 through a second single lens arrangement 7, which serves as an eyepiece and whose distance from the intermediate image B is approximately equal to the simple focal length f, the second common lens arrangement 7.

By means of the device according to the invention, the image diaphragm 20 generated in the far point F can have, for example, an opening width of 0.2 mm, so that a very high measuring accuracy can be achieved. This also makes it possible to move the far point F much closer to the eye 1 to be examined and to fix the device to the phoropter 13, the movement of the illuminating beam being caused by the rotating retinoscope mirror 3. The examination distance that can be achieved in this way can be kept small, which results in an extremely favorable distance of the examiner from the phoropter 13.

The lens arrangements 4, 6 and 7 specified above can represent individual lenses, but advantageously conventional lens combinations, in which case the distances described apply in each case to a main plane of the lens combination. In a test device, the optical system 17 had the following dimensions:

first distance (farthest point F - concentrating lens array 4): 22 mm focal length of the first collecting lens arrangement ^'4: 18 itm second distance (converging lens array 4 - aperture 5): 100 irm focal length of the relay lens system 6: 25 to remove the cover 6 from the reversal lens system: mm 8 Distance of the reversing lens system 6 from the first intermediate image B ..: 36 mm focal length of the second converging lens arrangement 7: 20 mm distance of the second focusing lens arrangement from the second intermediate image B: 20 mm examination distance: 100 mm distance of the examination eye 2 from the phoropter 13: 350 μm In the area of the replacement lens (s) 14, for example on the phoropter 13, an adapted periscope which can be pivoted into the optical axis A can be provided, with the aid of which the test specimen can view, for example, a conventional reading panel arranged behind the examiner.

This makes it possible for the examiner to compare the skiascopic examination result with the test specimen without any modifications or changes. It would also be conceivable to pivot the attachment lens (s) 14 out of the observation field at the same time, so that the pivotable add-on part can above all contain bare deflecting mirrors.

The device described above for examining the refractive condition of the eye can of course also be used in the same way for checking other optical systems and elements.

Claims

PATENT CLAIMS

1. A device for skiascoping, with a lighting device and a skiascope mirror, to which an aperture is connected on the examiner side, characterized in that a first converging lens arrangement (4) is at a first distance from the distant point (F) of the normal-sighted , optionally corrected eye (1) is provided, which lies between the single and double focal length (f ..) of the first converging lens arrangement (4), and that the diaphragm (5) on the examiner side depends on the first distance The second distance to the first converging lens arrangement (4) is greater than its double focal length (f-), the aperture (5) being reduced in the far point (F).

2. Device according to claim 1, characterized in that the diaphragm (5) on the examiner side is a reversing lens system (6), the distance from the diaphragm (5) is as small as possible.

3. Device according to claim 1 or 2, characterized in that the diaphragm (5) or the reversing lens system (6) on the examiner side is preceded by a second converging lens arrangement (7) whose distance from that of the first converging lens arrangement (4) first intermediate image (B ..) or to the second real intermediate image (B ") generated by the reversing lens system (6) is equal to the simple focal length ^• (f.,) of the second converging lens arrangement (7).

4. Device according to claim 1, characterized in that the distance of the first collecting lens arrangement (4) to the Fern¬ point (F) of the eye (1) to an extent between the simple and twice the focal length (f.) Of the first collection ¬ lens arrangement (4) is changeable.

5. Device according to claim 1 or 4, characterized in that the distance of the diaphragm (5) to the first intermediate image (B ..) of the first converging lens arrangement (4) is variable.