Lens for simulating human eyes

Abstract

The utility model discloses a lens for simulating human eyes, which belongs to the field of optical lenses and comprises an object plane, a first lens group, a diaphragm, a second lens group and an imaging plane which are sequentially arranged along a laser irradiation direction. The first lens group comprises a first lens and a first cemented lens. The second lens group comprises a fourth lens, a second cemented lens, a third cemented lens, a fourth cemented lens and an eleventh lens. The first lens, the first cemented lens and the third cemented lens have negative focal power, and the fourth lens, the second cemented lens, the fourth cemented lens and the eleventh lens have positive focal power. According to the utility model, the lens groups are arranged, the materials and the number of the lenses in each lens group are set, and the focal length ratio between the lenses is determined, so that light emitted from the surface of an object is imaged on a camera plane through the lens groups, and the MTF contrast index range of an edge view field is limited below the MTF contrast index range of a center view field; the lens better accords with human eye characteristics, and the simulation accuracy is improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to optical lens field, especially a lens for simulating human eye. BACKGROUND

[0002] The optical design of the human eye model in the past often restores the optical properties of each tissue of the eyeball, such as setting the cornea, the lens, the vitreous body, the retina and other layered structures respectively, and especially the imaging ability of the human eye is designed as a spherical fundus image plane. Nowadays, with the development of industrial testing needs, it is necessary to simulate the visual imaging of the human eye into an image signal, and to image the external scene on the camera plane to obtain an image. Therefore, the design of the human eye model in the past is not suitable for imaging on the plane as required for testing. And the conventional optical design pursues high-quality performance in each field of view, ignoring the fact that the human eye characteristics are focused on the center of the field of view, and the resolution of the edge of the field of view is reduced, which is not mentioned in the human eye characteristics. SUMMARY

[0003] The utility model provides a lens for simulating human eye for solving the problem that the lens for simulating human eye in the prior art ignores the fact that the resolution of the edge of the field of view is lower than that of the center of the field of view, which is a characteristic of the human eye.

[0004] A lens for simulating human eye, comprising:

[0005] An object plane, a first lens group, an aperture, a second lens group and an image plane are arranged in sequence along the direction of laser irradiation.

[0006] The first lens group comprises a lens one and a cemented lens one, and the second lens group comprises a lens four, a cemented lens two, a cemented lens three, a cemented lens four and a lens eleven.

[0007] The lens one, the cemented lens one and the cemented lens three have negative focal power, and the lens four, the cemented lens two, the cemented lens four and the lens eleven have positive focal power.

[0008] The cemented lens one comprises a lens two and a lens three; the lens two has positive focal power, and the lens three has negative focal power.

[0009] The cemented lens two comprises a lens five and a lens six, the cemented lens three comprises a lens seven and a lens eight, and the cemented lens four comprises a lens nine and a lens ten.

[0010] The lens five, the lens seven and the lens eight have negative focal power, and the lens six, the lens nine and the lens ten have positive focal power.

[0011] Preferably, the focal length ratio of the first lens group to the lens is -1.1 to -1, and the focal length ratio of the second lens group to the lens is 1.4 to 1.5.

[0012] The focal length ratio of the lens one to the lens is -1.8 to -1.7; the focal length ratio of the cemented lens one to the lens is -4 to -3, and the focal length ratio of the lens four to the lens is 2.2 to 2.3.

[0013] The focal length ratio of the lens two to the lens is 2.6 to 2.7; the focal length ratio of the lens three to the lens is -1.6 to -1.5;

[0014] The focal length ratio of the cemented lens two to the lens is 2.9 to 3, the focal length ratio of the lens five to the lens is -15 to -14, and the focal length ratio of the lens six to the lens is 3 to 3.1.

[0015] The focal length ratio of the cemented lens three to the lens is -4 to -3.0, the focal length ratio of the lens seven to the lens is -15 to -14, and the focal length ratio of the lens eight to the lens is -3.3 to -3.2.

[0016] The focal length ratio of the cemented lens four to the lens is 5.1 to 5.2, the focal length ratio of the lens nine to the lens is 110 to 120, and the focal length ratio of the lens ten to the lens is 9.1 to 9.2.

[0017] Preferably, the central MTF value of the lens under the corresponding use resolution is 0.6 to 1, and the edge MTF value is 0 to 0.3.

[0018] Compared with the prior art, the utility model discloses a lens structure, which comprises a lens group, and the material and quantity of the lens in each lens group are set to determine the focal length ratio between the lenses, so that the light emitted on the surface of an object is imaged on the camera plane through the lens group, and the edge field MTF contrast index range is limited below the central field MTF contrast index range, so that the lens is more in line with the characteristics of the human eye, and the simulation accuracy is improved. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 It is the structure schematic diagram of the lens of the utility model;

[0020] Figure 2 It is the MTF curve diagram of the lens of the utility model;

[0021] BRIEF DESCRIPTION OF DRAWINGS

[0022] 101-object plane, 201-first lens group, 211-lens one, 221-cemented lens one, 222-lens two, 223-lens three, 301-diaphragm, 401-second lens group, 411-lens four, 421-cemented lens two, 422-lens five, 423-lens six, 431-cemented lens three, 432-lens seven, 433-lens eight, 441-cemented lens four, 442-lens nine, 443-lens ten, 451-lens eleven, 501-protection window, 601-imaging plane. Detailed Implementation

[0023] The following describes a specific embodiment of the present invention in detail with reference to the accompanying drawings. However, it should be understood that the scope of protection of the present invention is not limited to the specific embodiment.

[0024] like Figure 1 and Figure 2 As shown, an embodiment of this utility model provides a lens for simulating the human eye, comprising an object plane 101, a first lens group 201, an aperture 301, a second lens group 401, a protective window 501, and an imaging plane 601 arranged in sequence.

[0025] Among them, the protective window 501 plays a protective role;

[0026] The light emitted from the object surface 101 passes sequentially through the first lens group 201, the aperture 301, the second lens group 401, and the first protective window 501, and forms an image 601 on the imaging surface.

[0027] The first lens group 201 is located in front of the aperture stop 301.

[0028] The first lens group 201 includes: lens one 211 and cemented lens one 221. Lens one 211 is a lens with negative optical power. Cemented lens one 221 includes: lens two 222 and lens three 223. Cemented lens one 221 is a lens with negative optical power. Lens two 222 is a lens with positive optical power, and lens three 223 is a lens with negative optical power.

[0029] The second lens group 401 includes: lens four 411, cemented lens two 421, cemented lens three 431, cemented lens four 441, and lens eleven 451. Lens four 411 is a lens with positive optical power. Cemented lens two 421 is a lens with positive optical power, cemented lens three is a lens with negative optical power, cemented lens four is a lens with positive optical power, and lens eleven 451 is a lens with positive optical power.

[0030] Cemented lens 2 421 includes lens 5 422 and lens 6 423. Lens 5 422 is a lens with negative optical power, and lens 6 423 is a lens with positive optical power.

[0031] Cemented lens 3 431 includes lens 7 432 and lens 8 433. Lens 7 432 is a lens with negative optical power, and lens 8 433 is a lens with negative optical power.

[0032] The gluing mirror four 441 includes a lens nine 442 and a lens ten 443. The lens nine 442 is a lens with positive optical power, and the lens ten 443 is a lens with positive optical power.

[0033] The lens of the first lens group 201 and the lens of the second lens group 401 are both glass lenses and spherical lenses.

[0034] According to the relationship between the field of view of the lens and the height of the object, H / D=tanθ=h / f, where H is the height of the object, D is the distance from the object to the lens, θ is the field of view, h is the height of the image, and f is the focal length. According to the ophthalmic examination standard, it is required to clearly see the black and white 7.3mm line width line at a distance of 5 meters, which is converted into optical parameters, i.e. the minimum resolvable angle of the human eye is 0.083 degrees;

[0035] According to the lens performance index MTF, the MTF abscissa is set to 120 per millimeter line logarithm with the conventional CCD camera parameters. When the lens is calculated according to the passing standard MTF index, the contrast is judged under the resolution of the abscissa per millimeter line logarithm in the use condition. When the contrast is above 0.6, the lens performance is good, and when the contrast is below 0.3, the lens performance is poor. Therefore, the central imaging performance of the lens is calculated according to the MTF index. The contrast at 120 per millimeter line logarithm is between 0.6 and 1, and the edge field imaging performance is between 0 and 0.3.

[0036] The current passing standard for ophthalmic examination is the visual acuity chart. According to the standard visual acuity chart, it is required to distinguish the black and white 7.3mm line width line at a distance of 5 meters. In order to achieve this goal, the MTF contrast index is converted to the contrast at 120 per millimeter line logarithm of the abscissa resolution, which is between 0.6 and 1.

[0037] The ratio of the first lens group 201 of the lens to the focal length of the lens is between -1.1 and -1, and the ratio of the second lens group 401 to the focal length of the lens is between 1.4 and 1.5.

[0038] The ratio of lens one 211 of the lens to the focal length of the lens is between -1.8 and -1.7; the ratio of cemented lens one 221 of the lens to the focal length of the lens is between -4 and -3.0; the ratio of lens two 222 of the lens to the focal length of the lens is between 2.6 and 2.7; the ratio of lens three 223 of the lens to the focal length of the lens is between -1.6 and -1.5; the ratio of lens four 411 of the lens to the focal length of the lens is between 2.2 and 2.3; the ratio of cemented lens two 421 of the lens to the focal length of the lens is between 2.9 and 3; the ratio of lens five 422 of the lens to the focal length of the lens is between -15 and -14; the ratio of lens six 423 of the lens to the focal length of the lens is between 3 and 3.1; the ratio of cemented lens three 431 of the lens to the focal length of the lens is between -4 and -3.9; the ratio of lens seven 432 of the lens to the focal length of the lens is between -15 and -14; the ratio of lens eight 433 of the lens to the focal length of the lens is between -3.3 and -3.2; the ratio of cemented lens four 441 of the lens to the focal length of the lens is between 5.1 and 5.2; the ratio of lens nine 442 of the lens to the focal length of the lens is between 110 and 120; the ratio of lens ten 443 of the lens to the focal length of the lens is between 9.1 and 9.2;

[0039] The corresponding central MTF value of the lens of the embodiment under the resolution used is between 0.6 and 1; the edge MTF value is between 0 and 0.3;

[0040] The embodiment simulates a single human eye viewing an optical imaging scene with a line width of 7.3 mm at a distance of 5 meters under a field of view angle range of 120°, and the light emitted from the object plane is imaged on the camera imaging plane of a CCD with a size of 6 mm.

[0041] Table of specific parameters of the objective lens system

[0042]

[0043] As Figure 2As shown, the MTF (Modulation Transfer Function) index is the most accurate and scientific evaluation standard for the lens. The ordinate can refer to contrast, ranging from 0 to 1, and the abscissa is the same, the closer the contrast is to 1, the better the lens imaging is. The abscissa represents the resolution, with units of line pairs per millimeter, and the ordinate is the same, the greater the abscissa resolution, the better the lens imaging is. The embodiments of the present application limit the lens MTF to 120 line pairs per millimeter: the central field of view contrast is above 0.6, below 1, and the edge field of view contrast is below 0.3, above 0. Because the lens is calculated by the passing standard MTF index, the contrast is judged at the abscissa resolution of line pairs per millimeter under the use condition, and it is considered that the lens performance is good when the contrast is above 0.6, and the lens performance is poor when the contrast is below 0.3. The purpose of the present embodiment is to show that the human eye characteristics are good for the central field of view imaging performance and the imaging performance decreases at the edge of the field of view.

[0044] It is obvious to a person skilled in the art that the present application is not limited to the details of the above exemplary embodiments, but can be implemented in other concrete forms without departing from the spirit and essential characteristics of the present application. Therefore, the embodiments should be considered as exemplary and non-limiting, and the scope of the present application is defined by the appended claims, not by the above description, and therefore all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present application. Any reference signs in the claims should not be considered as limiting the claims involved.

[0045] In addition, it should be understood that although the present specification is described in terms of embodiments, not every embodiment contains only one independent technical solution, and the description of the specification is only for clarity, and those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can be appropriately combined to form other embodiments that those skilled in the art can understand.

Claims

1. A lens for simulating the human eye, characterized in that, include: The object plane, the first lens group, the aperture, the second lens group, and the imaging plane are arranged sequentially along the laser irradiation direction; The first lens group includes lens one and cemented lens one, and the second lens group includes lens four, cemented lens two, cemented lens three, cemented lens four and lens eleven. Lens 1, cemented lens 1, and cemented lens 3 have negative optical power, while lens 4, cemented lens 2, cemented lens 4, and lens 11 have positive optical power.

2. The lens for simulating the human eye as described in claim 1, characterized in that, The cemented mirror includes a second lens and a third lens; the second lens has positive optical power, and the third lens has negative optical power.

3. The lens for simulating the human eye as described in claim 1, characterized in that, The cemented mirror 2 includes lens 5 and lens 6, the cemented mirror 3 includes lens 7 and lens 8, and the cemented mirror 4 includes lens 9 and lens 10. Among them, lenses five, seven, and eight have negative optical power, while lenses six, nine, and ten have positive optical power.

4. The lens for simulating the human eye as described in claim 1, characterized in that, The focal length ratio of the first lens group to the lens is -1.1 to -1, and the focal length ratio of the second lens group to the lens is 1.4 to 1.

5.

5. The lens for simulating the human eye as described in claim 1, characterized in that, The focal length ratio of lens one to the lens is -1.8 to -1.7; the focal length ratio of cemented lens one to the lens is -4 to -3; and the focal length ratio of lens four to the lens is 2.2 to 2.

3.

6. The lens for simulating the human eye as described in claim 2, characterized in that, The focal length ratio of lens 2 to lens is 2.6 to 2.7; the focal length ratio of lens 3 to lens is -1.6 to -1.

5.

7. The lens for simulating the human eye as described in claim 3, characterized in that, The focal length ratio of the second cemented lens to the lens is 2.9 to 3, the focal length ratio of the fifth lens to the lens is -15 to -14, and the focal length ratio of the sixth lens to the lens is 3 to 3.

1.

8. The lens for simulating the human eye as described in claim 3, characterized in that, The focal length ratio of the cemented lens three to the lens is -4 to -3.0, the focal length ratio of the lens seven to the lens is -15 to -14, and the focal length ratio of the lens eight to the lens is -3.3 to -3.

2.

9. The lens for simulating the human eye as described in claim 3, characterized in that, The focal length ratio of the cemented lens four to the lens is 5.1 to 5.2, the focal length ratio of the lens nine to the lens is 110 to 120, and the focal length ratio of the lens ten to the lens is 9.1 to 9.

2.

10. The lens for simulating the human eye as described in claim 1, characterized in that, The center MTF value of the lens at the corresponding resolution is 0.6 to 1, and the edge MTF value is 0 to 0.3.

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