System and Method for Determining Characteristic Values of Ametropia of a Test Person

Abstract

The disclosure relates to a system for determining characteristic values of ametropia of a test person, comprising a device for generating optical test structures and a device for observing the test structures by the test person, said device comprising a correction unit for correcting possible ametropia phenomena of the test person. According to the disclosure, the optical test structures have at least two moving speckle patterns of different wavelengths. The disclosure further relates to a corresponding device for generating optical test structures for determining characteristic values of ametropia of a test person, and to a corresponding method for determining characteristic values of ametropia of a test person.

Claims

1. System for determining characteristic values of an ametropia of a test person, comprising: a device for generating optical test structures; and a device for observing the test structures by the test person, wherein the device comprises a correction unit for correcting possible ametropia phenomena of the test person, wherein the optical test structures comprise at least two simultaneously shown and moving speckle patterns of different wavelengths.

2. System according to claim 1, wherein the device for generating optical test structures is configured as a projection device for projecting coherent light with at least two different wavelengths onto a screen surface which forms the test structures.

3. System according to claim 1, wherein the correction unit comprises at least one set of different correction lenses for correcting possible ametropia phenomena of the test person.

4. Device for generating optical test structures for determining characteristic values of an ametropia of a test person, according to claim 1, wherein the test structures comprise at least two simultaneously shown and moving speckle patterns with different wavelengths.

5. Device according to claim 4, wherein the device is configured as a projection device for projecting coherent light with at least two different wavelengths onto a screen surface which forms the test structures.

6. Device according to claim 5, wherein the device is adapted to generate the movement of the speckle pattern by a relative movement of the screen surface with respect to light beams of light of different wavelengths incident on this surface.

7. Device according to claim 6, wherein the device comprises at least one deflection unit for moving the light beams of light of the different wavelengths.

8. Device according to claim 5, wherein the device comprises an element providing the screen surface.

9. Device according to claim 8, wherein the device comprises an apparatus for moving the element providing the screen surface.

10. Method for determining characteristic values of an ametropia of a test person, the method comprising: generating optical test structures, wherein the optical test structures comprise at least two simultaneously shown and moving speckle patterns of different wavelengths; observing the test structures by the test person; and correcting the ametropia phenomena of the test person by means of a correction unit for correcting possible ametropia phenomena.

11. Device according to claim 4, wherein the device is a device for a system according to claim 1.

12. Device according to claim 8, wherein the element comprises a holographic structure.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0023] In the following, the disclosure will be explained by way of example with reference to the attached drawings based on exemplary embodiments, wherein the features shown below, both individually and in combination, may represent an aspect of the disclosure. In the drawing:

[0024] FIG. 1 shows a schematic representation of a farsighted eye observing speckle patterns;

[0025] FIG. 2 shows a schematic representation of an emmentrope eye observing speckle patterns;

[0026] FIG. 3 shows a system for determining characteristic values of an ametropia of a test person according to an embodiment of the disclosure;

[0027] FIG. 4 shows a first embodiment of a deflection unit of a device for generating moving speckle patterns;

[0028] FIG. 5 shows a second embodiment of a deflection unit of a device for generating moving speckle patterns;

[0029] FIG. 6 shows an embodiment of an apparatus for moving the screen which forms the speckle patterns; and

[0030] FIG. 7 shows a further device for generating moving speckle patterns.

DETAILED DESCRIPTION

[0031] FIG. 1 shows a schematic representation of a farsighted eye 10 of a test person who observes optical test structures 12 comprising two speckle patterns 14, 16 each moving with respect to the eye 10 or the head of the test person. The eye 10 is defined via its optical axis 18, its lens 20 and its retina 22. The cornea of the eye 10 and other details are omitted from this greatly simplified illustration. Since it is a farsighted eye 10, its focus 24 lies behind the retina 22. The two speckle patterns 14, 16 move in the same object plane 26 but have different colors or wavelengths. The movement of the speckle pattern 14 of higher wavelength (for example 650 nmred) is indicated by the arrow 28, the movement of the speckle pattern 16 of lower wavelength (for example 500 nmgreen) is indicated by the arrow 30. In the example shown, the speckle patterns 14, 16 move at the same speed in the same direction. The movement of the speckle patterns 14, 16 perceived by the test person is indicated by the arrows 32, 34. Here, arrow 32 indicates the perceived movement of the speckle pattern 14 of higher wavelength and arrow 34 indicates the perceived movement of the speckle pattern 16 of lower wavelength. The farsighted test person clearly perceives the movement of the speckle patterns 14, 16, wherein the perceived direction of movement corresponds to the actual direction of movement of the speckle patterns 14, 16. This is because the focus 24 is located behind the retina 22.

[0032] The situation is different for the shortsighted eye 10 (not shown). Here the focus 24 lies in front of the retina 22. The shortsighted test person also clearly perceives the movement of the speckle patterns 14, 16, wherein, however, the perceived direction of movement compared to the actual direction of movement of the speckle patterns 14, 16 is reversed.

[0033] FIG. 2 now shows the situation corresponding to FIG. 1 for the emmentropic eye 10 and for the farsighted eye 10, in which the hyperopia is completely compensated by an additional lens, for example a contact lens or eyeglasses. In the absence of ametropia or in the case of a complete compensation of the ametropia, now the chromatic aberration of the optical system (for example the lens 20) comes into play. If the ametropia for a medium wavelength (between the higher and the lower wavelength) is completely corrected, the perceived direction of movement of the speckle pattern 14 of higher wavelength continues to correspond to the actual direction of movement of this speckle pattern 14, whereas the perceived direction of movement of the speckle pattern 16 of lower wavelength is reversed with respect to the actual direction of movement of this speckle pattern 16. In this situation, the test person has the impression that both speckle patterns 14, 16 move in opposite directions, or that both speckle patterns 14, 16 are fixed.

[0034] This phenomenon can now be used by use of a system 36 described below for determining characteristic values of the ametropia of the test person.

[0035] FIG. 3 shows an example of such a system 36 for determining characteristic values of an ametropia of a test person. The system comprises (i) a device 38 for generating the optical test structures 12 with the two moving speckle patterns 14, 16 of different wavelengths and (ii) a device 42 configured as a phoropter 40 for observing these test structures 12 by the test person.

[0036] The device 38 for generating the optical test structures 12 with the two moving speckle patterns 14, 16 of different wavelengths comprises a projection device 44 with two projection modules 46, 48 for projecting coherent light with different wavelengths and a screen surface 50 forming the test structures. This surface 50 is formed, for example, by a screen (also called projection screen) 52 with a corresponding surface structure. The screen surface 50 or screen 52 can be considered as a separate system component of the system 36 or as a part of the device 38. Each of the projection modules 46, 48 comprises a light source 54 for coherent light of a respective wavelength, a respective optics 56 downstream of the light source 54 and a respective deflection unit 58 for moving the light beams of light of a corresponding wavelength. Thus, an optical path S is obtained.

[0037] The device 42 for observing test structures comprises a correction unit 60 for correcting possible ametropia phenomena of the test person and an actuating element 62 for actuating the correction unit 60. The correction unit 60 comprises a set of different correction lenses 64 for the correction.

[0038] In order to determine characteristic values of the ametropia of the eyes 10 of a test person, (i) the device 38 generates optical test structures 12, wherein the optical test structures 12 comprise two moving speckle patterns 14, 16 of different wavelengths, (ii) these test structures 12 are observed by the test person via the observation device 42 which comprises the correction unit 60 and (iii) corrections of the ametropia phenomena of the test person are carried out by means of the correction unit 60.

[0039] FIG. 4 shows a first embodiment of the deflection unit 58 of the device 38 for generating moving speckle patterns 14, 16. In this embodiment, the deflection unit 58 is configured as a mirror system in the manner of a polygon scanner. In the example shown, eight mirror elements 66 are arranged in the form of an octagon, which is rotatably mounted or rotated about the axis of rotation 68 (arrow). In this way one or more light beams can be moved.

[0040] FIG. 5 shows a second embodiment of the deflection unit 58 of the device for generating moving speckle patterns 14, 16. In this embodiment, the deflection unit 58 is configured as a mirror system in the manner of a galvo scanner. In the example shown, two mirror elements 66 (x and y mirror element) are rotatably mounted about corresponding axes of rotation 68. In this way one or more light beams can be moved.

[0041] FIG. 6 shows an embodiment of an apparatus 70 for moving the screen 52 which forms the speckle patterns 14, 16. This is formed as a screen in the form of a circumferential means wrapped around two rolls 72. At least one of the rolls 72 is configured as a drive roll and causes the screen to circulate around the rolls 72 (arrow).

[0042] FIG. 7 finally shows a further device 38 for generating moving speckle pattern 14, 16. This comprises a projection device 44 with two light sources 54 for coherent light of corresponding wavelengths, optics 56 downstream of the light sources 54 and a deflection unit 58 for moving the light beams of the light as well as an element 74 providing the screen surface 50, which comprises a holographic structure, i.e. a hologram. The use of an element 74 which comprises a holographic structure for providing the screen surface 50 enablesas shown herean illumination from the rear side, i.e. from the side of the element 74 facing away from the face 50 by the projection device 44.

[0043] It is to be understood that the foregoing is a description of one or more preferred exemplary embodiments of the invention. The invention is not limited to the particular embodiment(s) disclosed herein, but rather is defined solely by the claims. Furthermore, the statements contained in the foregoing description relate to particular embodiments and are not to be construed as limitations on the scope of the invention or on the definition of terms used in the claims, except where a term or phrase is expressly defined above. Various other embodiments and various changes and modifications to the disclosed embodiment(s) will become apparent to those skilled in the art. All such other embodiments, changes, and modifications are intended to come within the scope of the appended claims.

[0044] As used in this specification and claims, the terms for example, for instance, such as, and like, and the verbs comprising, having, including, and their other verb forms, when used in conjunction with a listing of one or more components or other items, are each to be construed as open-ended, meaning that the listing is not to be considered as excluding other, additional components or items. Other terms are to be construed using their broadest reasonable meaning unless they are used in a context that requires a different interpretation.

REFERENCE SYMBOLS

[0045] 10 eye [0046] 12 optical test structure [0047] 14 speckle pattern [0048] 16 speckle pattern [0049] 18 optical axis (eye) [0050] 20 lens (eye) [0051] 22 retina [0052] 24 focus [0053] 26 object plane [0054] 28 arrow (movement of speckle pattern of higher wavelength) [0055] 30 arrow (movement of speckle pattern of lower wavelength) [0056] 32 arrow (perceived movement of speckle pattern of higher wavelength) [0057] 34 arrow (perceived movement of speckle pattern of lower wavelength) [0058] 36 system for determining characteristic values of an ametropia [0059] 38 device for generating optical test structures [0060] 40 phoropter [0061] 42 device for observing test structures [0062] 44 projection device [0063] 46 projection module [0064] 48 projection module [0065] 50 screen surface [0066] 52 screen [0067] 54 light source [0068] 56 optics [0069] 58 deflection unit [0070] 60 correction unit [0071] 62 actuating element [0072] 64 set of correction lenses [0073] 66 mirror [0074] 68 axis of rotation [0075] 70 apparatus for moving the screen [0076] 72 rolls [0077] 74 hologram [0078] S optical path