Design method of double-aspheric-surface spectacle lens

Abstract

The invention discloses a design method of a double-aspheric-surface spectacle lens, particularly relates to the technical field of spectacle optics, and solves the problems that a spectacle lens design method in the prior art mainly considers the imaging quality of the lens itself in the mainstream and lacks comprehensive consideration of the imaging quality when the lens is combined with eyes; therefore, the technical problem that the lens can only carry out clear imaging in a central view field or a small view field angle is solved. According to the technical scheme, an aspherical lens design method combining a lens and an eye model is defined, so that the lens can be clearly imaged at any field angle of human eyes; according to the invention, the imaging quality of the spectacle lens under different field angles of human eyes is improved, and the effect of edge thinning is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of spectacle optics, and particularly relates to a design method for aspheric spectacle lenses. Background Art

[0002] Glasses are the main means for correcting refractive errors of the human eye. Currently, the lenses available on the market mainly include spherical lenses, aspheric lenses, progressive multifocal lenses, etc. Due to the higher design freedom and rotational symmetry of aspheric spectacle lenses, they can easily achieve a better imaging effect than spherical lenses, and their design and processing costs are lower than those of progressive multifocal lenses. Therefore, aspheric spectacle lenses occupy a dominant position in the spectacle market.

[0003] Currently, the mainstream method for designing spectacle lenses mainly considers the imaging quality of the lens itself, lacking comprehensive consideration of the imaging quality when the lens is combined with the eye, resulting in clear imaging of the lens only in the central field of view or within a small field of view angle. In order to design an aspheric lens that better fits the human eye, the lens and the human eye should be designed in combination, and the corresponding design theory should be proposed, which can effectively improve the imaging quality of the lens at other field of view angles. Summary of the Invention

[0004] Therefore, the present invention solves the technical problem in the prior art that the mainstream method for designing spectacle lenses mainly considers the imaging quality of the lens itself, lacking comprehensive consideration of the imaging quality when the lens is combined with the eye, resulting in clear imaging of the lens only in the central field of view or within a small field of view angle; a design method for aspheric spectacle lenses provided by the present invention solves the problem of the connection between the optical design of aspheric spectacle lenses and the human eye, and greatly improves the compatibility between the spectacle lens and the human eye.

[0005] The present invention provides a design method for double aspheric spectacle lenses, comprising the following steps:

[0006] S1: Determine the additional refractive power values required for clear imaging of the human eye at different viewing distances. Based on the model of the human eye during observation, by simulating the human eye model at different viewing distances, the refractive power that needs to be adjusted for clear imaging of the eye at different viewing distances is obtained;

[0007] S2: Establish the relationship between the field of view angle and the viewing distance, and obtain the refractive power that the eye needs to adjust at different field of view angles through the relationship among the field of view angle, the viewing distance, and the refractive power;

[0008] S3: Establish a lens-eye model, use double aspheric lenses, and constrain the refractive power of each part of the aspheric lens at the human eye field of view angle according to the change amount of the refractive power at different field of view angles and reduce the lens astigmatism, and finally obtain an aspheric lens that meets the requirements.

[0009] Among them, in step S1, the human eye model is established by using optical simulation software, and the vitreous thickness of the eye model is adjusted by changing the viewing distance of the human eye model, so as to obtain the vitreous thickness of the eye model for clear imaging at different viewing distances, and convert the change in vitreous thickness into the change in the refractive power of the eye model. The relationship between the change in the refractive power of the eye model and the viewing distance is obtained as follows:

[0010] F add =902.7 / y

[0011] Among them, F add is the change in refractive power, with the unit of D, and y is the viewing distance, with the unit of mm.

[0012] In step S2, a relationship between the field of view angle and the viewing distance is established:

[0013] y=10000 / |θ| θ∈[-20°,0°]|

[0014] Where y is the viewing distance, θ is the field of view angle, and the unit is °.

[0015] Among them, in step S2, the relationship between the change in the refractive power of the eye model and the field of view angle is established through the relationship between the change in the refractive power of the eye model, the viewing distance and the field of view angle:

[0016] F add =0.09027×|θ| θ∈[-20°,0°]|

[0017] Furthermore, in step S3, the aspherical lens is combined with the human eye model, and the refractive power of the lens at different viewing angles of the eye model is constrained according to the change in refractive power at different viewing angles, and the aspherical lens is optimized by reducing the astigmatism of the lens. According to the blurring limit of the human eye, the constraint range of the refractive power of the lens at different viewing angles is:

[0018] F θ =F+F add ±0.33

[0019] Where F θ is the refractive power range under different field angles, and F is the central refractive power of the lens.

[0020] Furthermore, in step S3, the aspheric surface equation is:

[0021]

[0022] Where: z is the vector height at the coordinate point (x, y), r is the distance from the point on the aspherical surface to the z-axis, c is the curvature of the aspherical vertex, and B, C, D, E, and F are the coefficients of the high-order terms of the aspherical surface.

[0023] In the above technical solution, the technical effects and advantages provided by the present invention are:

[0024] 1. The present invention provides a method for designing a double aspherical eyeglass lens, which clarifies the method for designing an aspherical lens that combines a lens with an eye model, effectively improves the fit between the lens and the human eye, and enables the lens to produce clear images at any viewing angle of the human eye.

[0025] 2. The present invention provides a method for designing a double aspherical spectacle lens. The designed aspherical lens also reduces the edge thickness of the lens and reduces the weight of the lens. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0027] Figure 1 is a schematic diagram of an eye model of the present invention;

[0028] Figure 2 This is a schematic diagram of the lens-eye model under a 0° field of view of the present invention;

[0029] Figure 3 This is a schematic diagram of the lens-eye model under a -20° field of view of the present invention;

[0030] Figure 4a and Figure 4b This is a MTF comparison chart of the aspherical eyeglass lens of the present invention and a spherical eyeglass lens of the same specification. DETAILED DESCRIPTION

[0031] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0032] Embodiment 1:

[0033] See also Figures 1-4b, an embodiment of the present invention provides a design method for dual aspheric eye lenses, firstly, a human eye model is established, the viewing distance of the eye model is changed and the length of the vitreous body of the eye model is adjusted at the same time, so that the eye model can form clear images at different viewing distances, and the change amount of the vitreous body of the eye model at different viewing distances is obtained, and the change amount is converted into the change amount of the refractive power of the eye model, so as to obtain the refractive power that needs to be adjusted for clear imaging of the eye model at different viewing distances; then, the relationship between the viewing angle and the change amount of the refractive power of the eye model is obtained through the relationship between the viewing distance and the field of view of the eye, and then the constraint range of the refractive power at different field of view angles is proposed according to the definition of the blur condition of the human eye; finally, the lens is combined with the human eye model, and the refractive power of the aspheric lens at different field of view angles of the human eye model is constrained and optimized through optical design software. The specific steps are as follows:

[0034] S1: Clarify the additional refractive power values ​​required for clear imaging of the human eye at different viewing distances. Based on the model of the human eye during observation, the human eye model at different viewing distances is simulated to obtain the refractive power required for clear imaging of the eye at different viewing distances. The specific steps are as follows:

[0035] The Liou ideal human eye model is established through optical design software, the viewing distance of the eye model is changed and the length of the vitreous body of the eye model is adjusted at the same time, so that the eye model can form clear images at different viewing distances. The vitreous body thickness of the eye model at different viewing distances is listed here, as shown in Table 1.

[0036] Table 1: Vitreous thickness table for clear imaging of objects at different distances in the eye model

[0037] Viewing distance (mm) ∞ 5000 3000 2000 1500 1000 750 500 Vitreous body thickness (mm) 16.239 16.311 16.359 16.418 16.476 16.589 16.751 16.907

[0038] Then the change in vitreous thickness is converted into the change in equivalent refractive power of the eye model. The conversion formula is: F add =(LL ∞ ) / 0.37

[0039] Where F add is the refractive power that needs to be increased under different field of view angles, L is the vitreous thickness corresponding to different viewing distances, and L∞ is the vitreous thickness corresponding to the viewing distance of infinity.

[0040] The change in the equivalent refractive power of the eye model at different viewing distances is obtained through transformation, as shown in Table 2 below.

[0041] Table 2: Equivalent refractive power change table of eye model for clear imaging of objects at different distances

[0042] Viewing distance (mm) ∞ 5000 3000 2000 1500 1000 750 500 <![CDATA[F add (D)]]> 0 0.195 0.324 0.484 0.641 0.946 1.384 1.805

[0043] The relationship between the viewing distance and Fadd obtained by fitting the data in Table 2 is:

[0044] F add =902.7 / y

[0045] Where y is the viewing distance.

[0046] S2: Establish the relationship between the field of view angle and the viewing distance, and obtain the refractive power that needs to be adjusted at different field of view angles through the relationship between the field of view angle, the viewing distance and the refractive power. The specific steps are as follows:

[0047] During observation, the human eye's field of view is approximately inversely proportional to the viewing distance. Based on this, the present invention establishes a relationship between the field of view and the viewing distance:

[0048] y=10000 / |θ| θ∈[-20°,0°]|

[0049] Through the relationship between the field of view angle, viewing distance and refractive power, the relationship between the different field of view angles of the eye and the equivalent refractive power that needs to be adjusted is obtained:

[0050] F add =0.09027×|θ| θ∈[-20°,0°]|

[0051] S3: Establish a lens-eye model, constrain the refractive power of each part of the aspheric lens under the human eye's field of view according to the change in refractive power under different field of view angles and reduce the aspheric lens astigmatism, and finally obtain an aspheric lens that meets the requirements. The specific steps are as follows:

[0052] Considering that the human eye will rotate downward when it moves from far vision to near vision, in order to ensure that the designed aspheric lens can form a clear image at any angle within the human eye's field of view, the present invention establishes a multiple structure with a field of view interval of 5° and a maximum angle of -20°, as shown in Table 3 below.

[0053] Table 3: Multiple structural parameters of the mirror-eye model

[0054] Structure 1 Structure 2 Structure 3 Structure 4 Structure 5 Viewing distance (mm) 1.0E+009 2000 1000 667 500 Field of view (°) 0 -5 -10 -15 -20

[0055] The equivalent refractive power change of the eye model under each structure is calculated through step S2. At the same time, based on the study of the blur boundary perceived by the human eye, the present invention limits the refractive power of the lens under different field angles to a range:

[0056] F θ =F+F add ±0.33

[0057] Where F θ is the refractive power range under different field angles, and F is the central refractive power of the lens.

[0058] In order to obtain human eye models with different refractive errors, the thickness of the vitreous body in the eye model is changed for simulation. The vitreous body thickness of eye models with different degrees can be calculated by the formula:

[0059] L=L e -0.37×F

[0060] Where L is the vitreous thickness of the ametropic eye model, L e The thickness of the vitreous body of a normal eye is 16.239 mm, and F is the degree of refractive error of the eye.

[0061] After obtaining the eye model with refractive error, the lens of the corresponding degree is placed in front of the eye model. First, the high-order coefficient of the front surface of the lens is set as a variable, and the refractive power range obtained under different field angles of the lens is used as the optimization target for optimization. After the optimization is completed, the high-order coefficient of the front surface of the lens is set to a fixed value. Then, the high-order coefficient of the back surface of the lens is set as a variable, the lens astigmatism is optimized, and the refractive power of the lens at each field angle is controlled to meet the requirements.

[0062] Embodiment 2:

[0063] In this embodiment, the material refractive index of the lens selected is 1.597, the refractive power is -8D, and the front surface base curve is 0.25D. The initial structure of the obtained spherical lens is shown in Table 4.

[0064] Table 4: Lens initial structure parameters

[0065] Lens refractive power Material refractive index Lens diameter Front surface curvature radius Rear surface curvature radius Central thickness Edge thickness -8D 1597 60 mm 238,800 mm 7,236 mm 120 mm 752 mm

[0066] The constraint range of the lens refractive power under different field angles calculated by the above formula is shown in Table 5.

[0067] Table 5: Target refractive power range of lenses at different field angles

[0068] Field of view (°) 0 -5 -10 -15 -20 <![CDATA[F θ (D)]]> -8.00±0.33 -7.55±0.33 -7.10±0.33 -6.65±0.33 -6.19±0.33

[0069] The refractive power range at each field angle in Table 5 is taken as the optimization target. After optimizing the lens by the above optimization method, the high-order coefficients and edge thickness of the front and back surfaces of the lens are obtained as shown in Table 6.

[0070] Table 6: High-order coefficients and edge thickness after lens optimization

[0071]

[0072] At the same time, the refractive power of the optimized aspheric lens at different field angles is shown in Table 7.

[0073] Table 7: Refractive power of aspherical lenses at different field angles

[0074] Field of view (°) 0 -5 -10 -15 -20 <![CDATA[F θ (D)]]> -8.00 -7.79 -7.30 -6.81 -6.57

[0075] From Table 6, we can see that the edge thickness of the lens is reduced from 7.52mm to 6.02mm at a half-diameter of 30mm, which is about 19.95% thinner. θ Compared with F in Table 5 θ By comparing the value range of , it was found that the refractive power of the optimized lens at each field of view angle was well matched. Only the refractive power at a field of view angle of -20° was slightly greater than the design value, with an error of only 0.05D, accounting for 0.81% of the standard refractive power at this field of view, indicating that the design theory is correct.

[0076] from Figure 4a and Figure 4b It can be seen that after the optimization of the lens-eye model, the imaging quality of the overall lens-eye model optical system has been significantly improved compared to the spherical lens. At the low frequency of 10lp / mm, the meridian and sagittal MTFs are both greater than 0.9, and the MTF at the high frequency of 30lp / mm is also greater than 0.5, which shows that the contrast and resolution of the lens have been significantly improved. The distance between the sagittal MTF and the meridian MTF curves at each field of view angle is close, which shows that the astigmatism of the lens at each field of view angle has been controlled.

[0077] The above description is only by way of illustration of certain exemplary embodiments of the present invention. It is undoubted that those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A method for designing a double aspherical spectacle lens, characterized in that: The steps include: S1: Clarify the additional refractive power value required for the human eye to form a clear image at different viewing distances; based on the model of the human eye during observation, by simulating the human eye model at different viewing distances, the refractive power required for the eye to form a clear image at different viewing distances is obtained; S2: Establish the relationship between the field of view angle and the viewing distance, and obtain the refractive power that needs to be adjusted at different field of view angles through the relationship among the field of view angle, the viewing distance and the refractive power; S3: Establish a lens-eye model, use double aspherical lenses, constrain the refractive power of each part of the aspherical lens under the human eye's field of view according to the change in refractive power under different field of view angles, and reduce the asphericity of the lens, and finally obtain an aspherical lens that meets the requirements.

2. The method for designing a double aspherical spectacle lens according to claim 1, characterized in that: In step S1, an optical simulation software is used to establish a human eye model. By changing the viewing distance of the human eye model and adjusting the vitreous thickness of the eye model at the same time, the vitreous thickness for clear imaging of the eye model at different viewing distances is obtained, and the change in vitreous thickness is converted into a change in the refractive power of the eye model.

3. The method for designing a double aspherical spectacle lens according to claim 2, characterized in that: The relationship between the change in the refractive power of the eye model and the viewing distance is: F add =902.7 / y Among them, F add is the change in refractive power, with the unit of D, and y is the viewing distance, with the unit of millimeters.

4. The method for designing a double aspherical spectacle lens according to claim 3, characterized in that: In step S2, a relationship between the viewing angle and the viewing distance is established: y=10000 / |θθ∈[-20°,0°] Where y is the viewing distance, θ is the field of view angle, and the unit is °.

5. The method for designing a double aspherical spectacle lens according to claim 4, characterized in that: In step S2, a relationship between the field of view angle and the change in the refractive power of the eye model is established: F add =0.09027×|θθ∈[-20°,0°]。 6. The method for designing a double aspherical spectacle lens according to claim 5, characterized in that: In step S3, the aspherical lens is combined with the human eye model, and the aspherical lens is optimized by constraining the refractive power of the lens at different viewing angles and reducing the astigmatism of the lens.

7. The method for designing a double aspherical spectacle lens according to claim 6, characterized in that: According to the blurriness limit of human eyes, the constraint range of the refractive power of lenses under different field of view angles is: F θ =F+F add ±0.33 Where F θ is the refractive power range under different field angles, and F is the central refractive power of the lens.

8. The method for designing a double aspherical spectacle lens according to claim 7, characterized in that: The aspheric surface equation in step S3 is: Where: z is the vector height at the coordinate point (x, y), r is the distance from the point on the aspherical surface to the z-axis, c is the curvature of the aspherical vertex, and B, C, D, E, and F are the coefficients of the high-order terms of the aspherical surface.

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