CN104849792A - Presbyopia correction device based on improved fractal zone plate - Google Patents

Abstract

The invention relates to a presbyopia correction device based on an improved fractal zone plate. According to the radius alpha, fractal level S, and light transmission ratio w within the period of the improved fractal zone plate, focusing of objects at different distances can be realized. A common artificial crystal material for the cataract surgery and the traditional binary phase type optical element process are used for processing. The improved fractal zone plate device can be used for presbyopia correction, thereby realizing clear object watching at a distant vision distance, a conversation distance, a computer working distance, or a reading distance. Therefore, a demand of clear imaging of objects at several kinds of distances by the presbyopia patients can be satisfied; the system has a simple structure; and convenient processing is realized. The device has the potential value in the presbyopia correction field.

Description

A kind of presbyopia based on the fractal zone plate of modified corrects device

Technical field

The invention belongs to vision correcting technical field.

Background technology

Along with the development of population structure aging trend, country and society rise just year by year to the attention rate of the Vision Health problem of mid-aged population.Presbyopia brings great inconvenience not only to middle-aged and old daily reading and work, also increases the potential safety hazard of the elderly and the traffic hazard incidence of society simultaneously.Under the overall background of population structure aging, the development of presbyopia correcting technology seems urgent and significant.

Normal eye has the optical imaging system of automatic focusing ability as one, can to the object blur-free imaging in sizable continuous distance range, this automatic focusing is by the distortion of human lens and mobilely realizes, and this process is called the adjustment of human eye.But along with the increase at age, the regulating power of human eye is degenerated gradually and finally disappears, and causes the symptom of being blurred, and this phenomenon is called presbyopia.Traditional presbyopia corrects means single focus, bifocus, progressive multi-focus lens etc., single focal lense (contact lenses and artificial lens) can only to specific range (being generally reading distance) blur-free imaging, and other local imagings unintelligible.Bifocal (contact lenses and artificial lens) is intended to the drawback overcoming single focal lense, wear this type of lens, human eye can to two ad-hoc location imaging clearlies (being generally infinite distance and reading distance) imaging, but for other intermediate distances, can not blur-free imaging.In order to obtain continuous print levelling thickness range, progressive multifocal frame eyeglasses is suggested, but these type of glasses then have apparent field is less, two side areas aberration cannot be eliminated defect.Presbyopia is obtained, and continuous print is clear looks thing scope, is finally pursuing a goal of correcting of presbyopia.This method that we propose is exactly the new try that presbyopia is corrected.

Meanwhile, in the treatment of current cataract of old people, intraocular lens's replacement operation has become a kind of method of mature and reliable, replaces original crystalline lens by implantable artificial crystal, can reach the effect recovering eyesight.The artificial lens with large depth of focus performance is then expected to correct presbyopia while recovery eyesight.Be intended to recover human eye at present and mostly be Bifocal intraocular's crystal depending on the artificial lens of thing scope continuously, the major defect of existence (part can be overcome by new three multifocal design) is exactly can see clearly at a distance and 2 points nearby, and center section does not see Chu.In order to overcome this defect, there is light sword artificial lens, light sword element is introduced phantom eye as artificial lens, though achieve large depth of focus performance, this kind of element processed complex.Have also appeared aspheric intraocular lens in recent years, and by adding suitable spherical aberration, achieving multifocal performance, but object distance position is chosen and can not be met reading distance.

Summary of the invention

The present invention seeks to the problems referred to above overcoming prior art existence, by choosing the parameter of the fractal zone plate of rational modified, determine the structure of the fractal zone plate of modified, after this zone plate and human eye being combined, make human eye can to the object blur-free imaging of different distance.

Presbyopia based on the fractal zone plate of modified provided by the invention corrects device, and be a fractal zone plate of modified, the structure of the fractal zone plate of described modified obtains by the following method:

, a transparent line segment, in each fractal iteration, by continuous light transmission part and lightproof part be the ratio of w by blacking in the middle of line segment, w gets positive count; This process can carry out iteration, and its iterative process as shown in Figure 1.By iterations, point form class time S of the fractal zone plate of modified determines that .w is definition like this: a point of form class iuuminting part is γ ₁, lightproof part is ξ ₁, first point of form class iuuminting part is γ ₂, lightproof part is ξ ₂, the ratio of a point of form class iuuminting part and lightproof part is w, namely if the radius size of the fractal zone plate of modified is a, the line segment that fractal iteration completes, using center as the initial point of coordinate axis, carries out coordinate transform according to formula (1),

$\mathrm{\ζ}={\left(\frac{r_0}{a}\right)}^2-\frac{1}{2}---\left(1\right)$

Be inswept 360 ° of turning axle with one end by the line segment after coordinate transform, formed figure is the fractal zone plate of modified.Wherein a is the radius size of the fractal zone plate of modified, r ₀for the horizontal ordinate under former coordinate system, ζ is the new coordinate after coordinate transform.The fractal zone plate of modified as shown in Figure 2.

This follow-on fractal zone plate is applied to human eye presbyopic when correcting, and can become a variable simple lens by abstract for the human eye of ideal image.Presbyopia phenomenon is then equivalent to these lens and loses focusing ability, becomes the simple lens that equivalent focal length in an air is f=22.22mm (being equivalent to human eye diopter is 60D, and image space refractive index is the liquid of 1.336, therefore image space focal length is about 16.67mm).Select wavelength X=555nm that human eye is the most responsive.The combination of research zone plate and human eye just can be reduced to the combination studying zone plate and lens.After human eye is combined with the fractal zone plate of modified, the focal length of whole system follows the focal length combinatorial formula of geometrical optics:

$\frac{1}{f}=\frac{1}{f_e}+\frac{1}{f_i}---\left(2\right)$

F in formula _efor human eye focal length, f _ifor the focal length of the fractal zone plate of modified focus at different levels.

Combine through focal length, each focus redistribution of the fractal zone plate of modified, under different color light, these a large amount of focuses are overlapped, thus the large depth of focus performance of fractal for modified zone plate is transferred in the system after being combined with human eye, thus make human eye obtain large depth of focus performance, achieve the effect to object blur-free imaging in continuous distance range.

In a preferred embodiment of invention, as use a=1.5mm, w=1, when presbyopia corrected by the fractal zone plate of standard of point form class time s=3, respectively can to the object blur-free imaging of 246.1mm (reading distance), 351.8mm (computer operation distance), 829.0mm (talk distance), infinite point.

In another preferred embodiment of invention, as use a=1.5mm, w=0.5, when presbyopia corrected by the fractal zone plate of standard of point form class time s=3, respectively can to the object blur-free imaging of 210.67mm, 580mm, infinite point.

According to the fractal zone plate structure of the modified designed, using polymethyl-benzene e pioic acid methyl ester (PMMA), Silica hydrogel, hydrogel or acrylate polymer as making material, the processing technology manufacture that this device can use binary optical elements general.

The presbyopia of fractal for the modified produced zone plate rectification device is added and climbs the available artificial lens be made into for cataract operation.

The presbyopia of the fractal zone plate of this modified is corrected device and be can be used for frame eyeglasses or corneal inlay body.

Advantage of the present invention and beneficial effect

Fractal for modified zone plate is introduced presbyopia and is corrected by the present invention, and the large depth of focus functional improvement utilizing the fractal zone plate of modified to have loses the depth of focus of the human eye of regulating power, achieves the blur-free imaging of different distance object.

Accompanying drawing explanation

Fig. 1 is the fractal iterative process of modified.

Fig. 2 is the schematic diagram of the fractal zone plate of w=1, s=3 modified.

Fig. 3 is a=1.5mm, w=1, the optical field distribution after the zone plate of point form class time s=3 and human eye group.

Fig. 4 be the bore hole that loses regulating power with utilize the fractal zone plate of modified correct after eyes to the contrast imaging simulation figure of the E word of different distance.Left column figure is bore hole imaging effect, and right row figure is the imaging effect after rectification.Z _odifferent values reflect the change of object distance.

Fig. 5 is a=1.5mm, w=0.5, the optical field distribution after the fractal zone plate of standard of point form class time s=3 and human eye combine.

Embodiment

Below in conjunction with accompanying drawing, the present invention is described in further detail.

As shown in Figure 1, a transparent line segment, in each fractal iteration, by the ratio of continuous light transmission part and lightproof part be w by blacking in the middle of line segment, positive count can be got.Point form class time S of the fractal zone plate of modified is determined by iterations, as long as processing technology allows, can carry out unlimited fractal in theory.The radius size a of the fractal zone plate of modified can desirable 1.5mm to 3mm.The line segment that fractal iteration completes, using its center as the initial point of coordinate axis, carries out coordinate transform according to formula (1).Be inswept 360 ° of turning axle with one end by the line segment after coordinate transform, formed figure is the fractal zone plate of modified.

Accompanying drawing 2 is fractal zone plate structural representations of modified of w=1, s=3.

According to the fractal zone plate structure of the modified designed, the general material (as PMMA, Silica hydrogel, hydrogel or acrylate polymer) of contact lens can be used, adopt phase compensating method, with the processing technology processing that binary optical elements is general.

Principle of work of the present invention:

According to scalar diffraction theory, for the pupil function with round symmetric profile, its on-axis intensity distributes according to following formula:

$I\left(z\right)={\left(\frac{2\mathrm{\π}}{\mathrm{\λz}}\right)}^2{\left|{\∫}_0^{b}p\left(r\right)\exp (-i\frac{\mathrm{\π}}{\mathrm{\λz}}{r}^2)\mathrm{r\; dr}\right|}^2---\left(3\right)$

Wherein, λ is optical wavelength, and z is axial distance, and b is pupil radius, p (r ₀) be the pupil function expression formula that is independent variable with the radial radius r of pupil.

If the pupil function of the fractal zone plate of modified obtained by above-mentioned iteration and conversion is expressed as q (ξ), (1) formula of substitution pushes away axial intensity meets following formula:

$I_0=I_{\mathrm{GZP}}(u,N,S,w)\underset{i=1}{\overset{S-1}{\mathrm{\Π}}}\frac{{\sin }^2\left[\mathrm{\πNu}(1+1/w){(w/(\mathrm{Nw}+N-1))}^i\right]}{{\sin }^2\left[\mathrm{\πu}(1+1/w){(w/(\mathrm{Nw}+N-1))}^i\right]}---\left(4\right)$

Wherein, $I_{\mathrm{GZP}}(u,N,S,w)={4\sin }^2\left(\mathrm{\πu}{(w/(\mathrm{Nw}+N-1))}^s\right)\frac{{\sin }^2\left[\mathrm{\πMu}(1+1/w){(w/(\mathrm{Nw}+N-1))}^s\right]}{{\sin }^2\left[\mathrm{\πu}(1+1/w){(w/(\mathrm{Nw}+N-1))}^s\right]}---\left(5\right)$

U is axial coordinate, N be first iteration time residue line segment number, S is point form class time, and w refers to the ratio of a point of form class iuuminting part and lightproof part.Set parameter w, point form class time S, radius size a substitute into (3) (4) formula and calculate the focus distribution that can obtain the fractal zone plate of modified.

The fractal zone plate of modified has a large amount of focuses meeting fractal theory distribution, and under different color light, these focuses are overlapped defines large depth of focus.Depth of focus refers to the knots modification of the image distance of the scope inner optical system allowed in image planes sharpness.Depth of focus corresponds to the depth of field of object space, and the object be namely imaged in focal depth range can be considered as being comparatively clearly imaging.Therefore, the depth of focus increasing optical system just can realize the imaging comparatively clearly of the object within the scope of certain distance.The presbyopia antidote based on the fractal zone plate of modified that the present invention proposes is exactly the thought based on utilizing the fractal zone plate of modified to increase human eye depth of focus.

The human eye losing regulating power due to presbyopia can regard as focal length and be fixed as f _ethe simple lens of ≈ 16.667mm.After human eye is combined with the fractal zone plate of modified, the focal length of whole system follows the focal length combinatorial formula of geometrical optics:

$\frac{1}{f}=\frac{1}{f_e}+\frac{1}{f_i}---\left(6\right)$

F in formula _efor human eye focal length, f _ifor the focal length of the fractal zone plate of modified focus at different levels.

Combine through focal length, each focus redistribution of the fractal zone plate of modified, under different color light, these a large amount of focuses are overlapped, thus the large depth of focus performance of fractal for modified zone plate is transferred in the system after being combined with human eye, thus make human eye obtain large depth of focus performance, achieve the effect to object blur-free imaging in continuous distance range.

The example that the fractal zone plate of modified in the present invention is applied to presbyopia rectification is as follows:

Choose human eye sensitivity wavelength X=555nm, the diopter of human eye is 60D, and the parameter of accurate fractal zone plate is a=1.5mm, w=1, point form class time s=3.This accurate fractal zone plate and human eye are combined, analyzes its imaging effect.

Fig. 3 give this zone plate and human eye combine after optical field distribution.After adopting this zone plate, human eye respectively can to the object blur-free imaging of 246.1mm, 351.8mm, 829.0mm, infinite point.In order to a nearlyer step analyzes its imaging performance, choose object distance Z respectively _othe letter e of=100mm, 250mm, 600mm, 2000mm and 250000mm carries out emulation experiment.Each object distance chosen all possesses realistic meaning: 100mm is the minimum distance that normal eye can see clearly, 250mm is the distance of distinct vision of normal eye, significant for reading and some fine works, 600mm is the distance of normal person when using computing machine between eyes and screen, 2000mm is sighting distance when generally walking, 250000mm can be similar to and regard infinite distance as, looks into the distance situation at a distance corresponding to people.

Fig. 4 shows the bore hole (left figure) that loses regulating power with utilize the fractal zone plate of modified correct after eyes (right figure) to the contrast imaging simulation figure of the letter e of different distance.Left figure reflects intuitively and does not adopt the human eye of corrective measure in serious presbyopia (losing regulating power) situation, and image quality reduces the phenomenon that sharply reduces along with object distance.As can be seen from right figure, the application of the fractal zone plate of modified significantly improves the image quality at each object distance place, also namely achieves the blur-free imaging to object in continuous distance range.

Choose human eye sensitivity wavelength X=555nm, the diopter of human eye is 60D, and the parameter of accurate fractal zone plate is a=1.5mm, w=0.5, point form class time s=3.This accurate fractal zone plate and human eye are combined, analyzes its imaging effect.Its light distribution as shown in Figure 5.Result shows that this combination respectively can to the object blur-free imaging of 210.67mm, 580mm, infinite point.

Claims (6)

1. the presbyopia based on the fractal zone plate of modified corrects a device, and it is characterized in that described presbyopia is corrected device and is a fractal zone plate of modified, the structure of the fractal zone plate of described modified obtains by the following method:

, a transparent line segment, in each fractal iteration, by continuous light transmission part and lightproof part be the ratio of w by blacking in the middle of line segment, w gets positive count; Point form class time S of the fractal zone plate of modified is determined by iterations, and the radius size of the fractal zone plate of modified is a, and the line segment that fractal iteration completes, using its center as the initial point of coordinate axis, carries out coordinate transform according to formula (1),

$\mathrm{\ζ}={\left(\frac{r_0}{a}\right)}^2-\frac{1}{2}---\left(1\right)$

Wherein, r ₀for the horizontal ordinate under former coordinate system, ζ is the new coordinate after coordinate transform, and be inswept 360 ° of turning axle with one end by the line segment after coordinate transform, formed figure is the fractal zone plate of modified.

2. correct device based on the presbyopia of the fractal zone plate of modified as claimed in claim 1, it is characterized in that the value of the fractal zone plate of described modified is radius a=1.5mm, s=3, during w=1, verify in phantom eye, be applied to presbyopic rectification, can obtain and look thing depending on far away, talk distance, the clear of computer operation Distance geometry reading distance.

3. correct device based on the presbyopia of the fractal zone plate of modified as claimed in claim 1 or 2, it is characterized in that the presbyopia of the fractal zone plate of described modified corrects device is a phase-type device, utilizes the processing technology manufacture of traditional Binary-phase bit-type optical element.

4. correct device based on the presbyopia of the fractal zone plate of modified as claimed in claim 1 or 2, it is characterized in that the material polymethyl-benzene e pioic acid methyl ester (PMMA) of the presbyopia rectification device of the fractal zone plate of described modified, Silica hydrogel, hydrogel or acrylate polymer.

5. correct device based on the presbyopia of the fractal zone plate of modified as claimed in claim 1 or 2, it is characterized in that the presbyopia of the fractal zone plate of described modified is corrected device and added the artificial lens of climbing and can be made into for human eye cataract operation.

6. correct device based on the presbyopia of the fractal zone plate of modified as claimed in claim 1 or 2, it is characterized in that the presbyopia of the fractal zone plate of described modified is corrected device and can be applied to frame eyeglasses or corneal inlay body (corneal inlay).