Abstract:
The invention provides an anti-radiation structure comprising a substrate, a reflective layer adjacent to the substrate, and a periodic grating adjacent to the reflective layer. The invention also provides another anti-radiation structure comprising a substrate and a periodic grating adjacent to the substrate. The described structures may reflect or diffract incident radiation at a specific wavelength.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The invention relates to an anti-radiation structure, and in particular relates to a periodic grating structure on the substrate surface, thereby reflecting or diffracting an incident radiation at a specific wavelength. 
         [0003]    2. Description of the Related Art 
         [0004]    Cataracts are not rare in oldster ocular disease. In eyeball structure, the lens is a little convex and located behind the pupil of the eye, thereby focusing incident light and forming an image on the retina. Because veins distributed on the eyeball are few, thermolysis of the eyeball is deficient. If exposed to ultraviolet light, the lens, under heat may undergo pathological change, e.g. a turbid lens referred to as cataract. 
         [0005]    In addition, colorblindness is a common eye disease. Eyes can distinguish different colors by specific pigments of photosensitive retina cells. Each photosensitive cell has one specific pigment (red, green, and blue), such as photosensitive particles on camera film. 
         [0006]    Colorblindness cannot correctly discriminate colors, or confuse specific colors. Men have a higher probability than women to be colorblind. 8% of men are colorblind, and only 0.5% of women are colorblind. Most colorblind are color weak, and the people with full colorblindness are only 1/100,000. 
         [0007]    Daltonism is congenital colorblindness and cannot be cured. Sufferers of daltonism are almost all men. Most daltonism sufferers are red-green colorblind, and are unable to distinguish purple-blue. 
         [0008]    Another kind of colorblindness is acquired due to pathological changes in retina or optical nerves, such as trauma or glaucoma. Most acquired colorblindness cannot distinguish yellow-blue, but can easily distinguish blue-purple. Daltonism (red-green colorblindness) is difficult to cure by conventional medicine, however, most colorblindness is color weak. Color weak is weak in determining colors and not full colorblind. 
         [0009]    Current treatment of cataracts involves transplanting an artificial lens, but the effect of this surgical operation is different for different patients. Additionally, color weakness is one of sapiens eye diseases. Therefore, an anti-radiation structure reflecting or diffracting an incident radiation at a specific wavelength range is called for improving and preventing the described eye diseases. 
       BRIEF SUMMARY OF THE INVENTION 
       [0010]    Accordingly, the invention provides an anti-radiation structure which reflects or diffracts an incident radiation at a specific wavelength, thereby reducing the danger of exposure to the radiation, and modifying the color distinguishing ability of color weak people. 
         [0011]    The invention provides an anti-radiation structure, comprising a substrate; a reflective layer adjacent to the substrate; and a periodic grating adjacent to the reflective layer for reflecting an incident radiation. 
         [0012]    The invention further provides an anti-radiation structure, comprising a substrate and a periodic grating adjacent to the substrate for diffracting an incident radiation. 
         [0013]    A detailed description is given in the following embodiments with reference to the accompanying drawings. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    The invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein: 
           [0015]      FIGS. 1-4  are cross sections of anti-radiation structures of the invention; 
           [0016]      FIGS. 5-11  are a schematic view showing simulated reflection results versus different wavelength of incident light according to the invention; and 
           [0017]      FIG. 12  is a schematic view showing simulated transmission results versus different wavelength of incident light according to the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0018]    The following description is of the best-contemplated mode of carrying out the invention. This description is made for the purpose of illustrating the general principles of the invention and should not be taken in a limiting sense. The scope of the invention is best determined by reference to the appended claims. 
         [0019]    The invention provides simulated experiments to show the anti-radiation effect, such as UV light, blue light, and red light. The invention can be applied in lens, window, or other anti-radiation structures. For simplifying the factors of the simulated experiments, material dispersion is neglected, and the incident light is hypothesized to be perfect coherence and normal incidence. 
         [0020]      FIG. 1  is a cross section of an anti-radiation structure  100  including a substrate  101 , a reflective layer  103 , and a periodic grating  105 . The substrate  101  may be glass, plastic, or organic-inorganic composite, with glass used in the simulated embodiments of the invention. The reflective layer  103  and the periodic grating  105  have a refractive index of 1.4 to 2.0. In preferred embodiments, the reflective layer  103  and the periodic grating  105  have substantially greater refractive indices than the substrate  101 . Furthermore, the reflective layer  103  and the periodic grating  105  can be same or different materials, and the reflective layer  103  and the periodic grating  105  may be in-mold if the same material. 
         [0021]    For preventing cataracts, the invention provides an anti-radiation structure  100  to reflect the incident UV light of 200 nm to 400 nm, with indices of the reflective layer  103  and the periodic grating  105  substantially exceeding that of the substrate  101 , and more preferably about 1.6 to 2.0. The duty cycle of periodic grating  105 , ratio of grating width to grating period, is preferably 0.15 to 0.8, and more preferably about 0.2 to 0.3. The grating period is preferably about 10 nm to 500 nm, and more preferably about 100 nm to 200 nm. The grating height H is about 50 nm to 210 nm. The thickness d of the reflective layer  103  is about 5 nm to 70 nm. 
         [0022]    For modifying red color vision deficiency, the invention provides another anti-radiation structure  200  as shown in  FIG. 2 . The anti-radiation structure  200  reflects the incident short wavelength light of 400 nm to 550 nm, such that red color perception is accurate. The indices of the reflective layer  203  and the periodic grating  205  substantially exceed that of the substrate  201 , and more preferably are about 1.6 to 2.0. The duty cycle of the periodic grating  205  is preferably 0.15 to 0.8, and more preferably about 0.2 to 0.3. The grating period is preferably about 10 nm to 500 nm, and more preferably about 100 nm to 200 nm. The grating height H is about 50 nm to 210 nm. The thickness d of the reflective layer  203  is about 10 nm to 120 nm. 
         [0023]    For modifying the blue color vision deficiency, the invention provides another anti-radiation structure  300  as shown in  FIG. 3 . The anti-radiation structure  300  reflects the incident long wavelength light of 550 nm to 700 nm, such that blue color perception is accurate. The indices of the reflective layer  303  and the periodic grating  305  substantially exceed that of the substrate  301 , and more preferably about 1.6 to 2.0. The duty cycle of the periodic grating  305  is preferably 0.15 to 0.8, and more preferably are about 0.25 to 0.4. The grating period is preferably about 10 nm to 500 nm, and more preferably about 100 nm to 200 nm. The grating height H is about 5 nm to 130 nm. The thickness d of the reflective layer  203  is about 50 nm to 180 nm. 
         [0024]    In addition to the disclosed three-layer structure, the invention also provides an anti-radiation structure  400  without reflective layer, as shown in  FIG. 4 . The anti-radiation structure  400  includes a substrate  401  and a periodic grating  405 . The substrate  401  may be glass, plastic, or organic-inorganic composite, with glass used in the simulated embodiments of the invention. The periodic grating  405  may be glass, plastic, or organic-inorganic composite. In preferred embodiments, the substrate  401  and the periodic grating  405  have substantially similar refractive index, and the substrate  401  and the periodic grating  405  can be same or different materials. The periodic grating  405  and the substrate  401  may be in-mold if the same material. For reflecting the incident UV light of 200 nm to 400 nm, the duty cycle the periodic grating  405  is preferably 0.1 to 0.9. The grating period is preferably about 180 nm to 340 nm. The grating height H is about 10 nm to 400 nm. 
         [0025]    Simulated Experiment I 
         [0026]    Table I shows the simulated variables of UV reflection of the anti-radiation structure  100 . The refractive index of the substrate  101  is 1.5. Variables of Simulated experiment I include grating height H, thickness d of the reflective layer  103 , refractive index of the periodic grating  105  and the reflective layer  103  (the periodic grating  103  and the reflective layer  105  are hypothesized to be same material), duty cycle, and grating period T. #5 means no reflective layer and periodic grating are on the substrate  101 , i.e. only substrate  101  processes simulation of reflection. Simulated experiment I utilizes transverse electric (TE) light and transverse magnetic (TM) light as incident light.  FIG. 5  shows simulated results of reflection versus wavelength, wherein curves  1 - 5  correspond to #1-5 in Table I. Compared to substrate (#5), the anti-radiation structures of the invention (#1-4) have higher reflection to 200-400 nm UV light, as shown in  FIG. 5 . Specifically, if the reflective layer  103  and the periodic grating  105  have higher refractive index (1.9) such as #3 and #4, the anti-radiation structure has higher reflection of about 8% to 14%. 
         [0000]    
       
         
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                   
                 TABLE I 
               
               
                   
                   
               
               
                   
                 #1 (TE) 
                 #2 (TM) 
                 #3 (TE) 
                 #4 (TM) 
                 #5 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 Grating height H 
                 146 nm 
                 146 nm 
                 135 nm 
                 135 nm 
                 0 
               
               
                 Thickness d of the 
                  31 nm 
                  31 nm 
                  26 nm 
                  26 nm 
                 0 
               
               
                 Reflective layer 
               
               
                 Refractive index 
                 1.6  
                 1.6  
                 1.9  
                 1.9  
                 1.5 
               
               
                 Duty cycle 
                 0.28 
                 0.28 
                 0.28 
                 0.28 
               
               
                 Grating period 
                 130 nm 
                 130 nm 
                 130 nm 
                 130 nm 
               
               
                   
               
             
          
         
       
     
         [0027]    Simulated Experiment II 
         [0028]    Table II shows the simulated variables of short-length visible light reflection of the anti-radiation structure  200 . The refractive index of the substrate  201  is 1.5. Variables include grating height H, thickness d of the reflective layer  203 , refractive index of the periodic grating  205  and the reflective layer  203  (the periodic grating  203  and the reflective layer  205  are hypothesized to be same material), duty cycle, and grating period T. #10 means that no reflective layer and periodic grating are on the substrate  201 , i.e. only substrate  201  processes simulated reflection. Simulated experiment II utilizes transverse electric (TE) light and transverse magnetic (TM) light as incident light.  FIG. 6  shows simulated results of reflection versus wavelength, wherein curves  6 - 10  correspond to #6-10 in Table II. Compared to substrate (#10), the anti-radiation structures of the invention (#6-9) have higher reflection to 400-550 nm visible light, as shown in  FIG. 6 . Specifically, if the reflective layer  203  and the periodic grating  205  have higher refractive index (1.9) such as #8 and #9, the anti-radiation structure has higher reflection of about 6% to 17%. 
         [0000]    
       
         
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                   
                 TABLE II 
               
               
                   
                   
               
               
                   
                 #6 (TE) 
                 #7 (TM) 
                 #8 (TE) 
                 #9 (TM) 
                 #10 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 Grating height H 
                 145 nm 
                 145 nm 
                 146 nm 
                 146 nm 
                 0 
               
               
                 Thickness d of the 
                  81 nm 
                  81 nm 
                  51 nm 
                  51 nm 
                 0 
               
               
                 Reflective layer 
               
               
                 Refractive index 
                 1.6 
                 1.6 
                 1.9 
                 1.9 
                 1.5 
               
               
                 Duty cycle 
                 0.28 
                 0.28 
                 0.28 
                 0.28 
               
               
                 Grating period 
                 130 nm 
                 130 nm 
                 130 nm 
                 130 nm 
               
               
                   
               
             
          
         
       
     
         [0029]    Table III shows the simulated variables of short-length visible light reflection of the anti-radiation structure  200  with different thicknesses d of the reflective layer  203 . The refractive index of the periodic grating  205  and the reflective layer  203  is 1.6, the grating height H is 145 nm, and grating period is 130 nm.  FIG. 7  shows simulated results of reflection versus wavelength, wherein curves  11 - 14  correspond to #11-14 in Table III.  FIG. 7  shows that curves  11  and  13  have higher reflection, of about 3% to 6%, to short-length visible blue light. When the thickness d of the reflective layer  203  is thicker than 100 nm, the anti-radiation structure  200  (curve  12 ) has lower reflection, to the short-length visible blue light, than substrate  201  (curve  14 ). 
         [0000]    
       
         
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                   
                 TABLE III 
               
               
                   
                   
               
               
                   
                 Thickness 
                   
                   
                   
                   
               
               
                   
                 d of the 
                 Grating 
                 Refractive 
                   
                 Grating 
               
               
                   
                 Reflective layer 
                 height H 
                 index 
                 Duty cycle 
                 period 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 #11 (TE) 
                 81 nm 
                 145 nm 
                 1.6 
                 0.28 
                 130 nm 
               
               
                 #12 (TE) 
                 112 nm  
                 145 nm 
                 1.6 
                 0.28 
                 130 nm 
               
               
                 #13 (TE) 
                 50 nm 
                 145 nm 
                 1.6 
                 0.28 
                 130 nm 
               
               
                 #14 
                 0 
                 0 
                 1.5 
               
               
                   
               
             
          
         
       
     
         [0030]    Table IV shows the simulated variables of short-length visible light reflection of the anti-radiation structure  200  with different thicknesses d of the reflective layer  203 . The refractive index of the periodic grating  205  and the reflective layer  203  is 1.9, the grating height H is 146 nm, and grating period is 130 nm.  FIG. 8  shows simulated results of reflection versus wavelength, wherein curves  15 - 18  correspond to #15-18 in Table IV.  FIG. 8  shows that curves  15  and  16  have higher reflection, of about 6% to 17%, to short-length visible blue light. Even when the thickness d of the reflective layer  203  is as thin as 25 nm, the anti-radiation structure  200  (curve  17 ) still has higher reflection, to the short-length visible blue light, than substrate  201  (curve  18 ). In this simulated result, the reflective layer  203  with higher refractive index has higher reflection to the short-length visible blue light. 
         [0000]    
       
         
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                   
                 TABLE IV 
               
               
                   
                   
               
               
                   
                 Thickness 
                   
                   
                   
                   
               
               
                   
                 d of the 
                 Grating 
                 Refractive 
                   
                 Grating 
               
               
                   
                 Reflective layer 
                 height H 
                 index 
                 Duty cycle 
                 period 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 #15 (TE) 
                 51 nm 
                 146 nm 
                 1.9 
                 0.28 
                 130 nm 
               
               
                 #16 (TE) 
                 77 nm 
                 146 nm 
                 1.9 
                 0.28 
                 130 nm 
               
               
                 #17 (TE) 
                 25 nm 
                 146 nm 
                 1.9 
                 0.28 
                 130 nm 
               
               
                 #18 
                 0 
                 0 
                 1.5 
               
               
                   
               
             
          
         
       
     
         [0031]    Simulated Experiment III 
         [0032]    Table V shows the simulated variables of long-length visible light reflection of the anti-radiation structure  300 . The refractive index of the substrate  301  is 1.5. Variables include grating height H, thickness d of the reflective layer  303 , refractive index of the periodic grating  305  and the reflective layer  303  (the periodic grating  303  and the reflective layer  305  are hypothesized to be same material), duty cycle, and grating period T. #25 means that no reflective layer and periodic grating are on the substrate  301 , i.e. only substrate  201  processes simulated reflection. Simulated experiment II utilizes transverse electric (TE) light and transverse magnetic (TM) light as incident light.  FIG. 9  shows simulated results of reflection versus wavelength, wherein curves  21 - 25  correspond to #21-25 in Table V. Compared to substrate (#25), the anti-radiation structures of the invention (#21-24) have higher reflection to 550-700 nm visible light, as shown in  FIG. 9 . Specifically, if the reflective layer  303  and the periodic grating  305  have higher refractive index (1.9) such as #23 and #24, the anti-radiation structure has higher reflection of about 9% to 14%. 
         [0000]    
       
         
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                   
                 TABLE V 
               
               
                   
                   
               
               
                   
                 #21 (TE) 
                 #22 (TM) 
                 #23 (TE) 
                 #24 (TM) 
                 #25 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 Grating height H 
                  70 nm 
                  70 nm 
                  60 nm 
                  60 nm 
                 0 
               
               
                 Thickness d of 
                 135 nm 
                 135 nm 
                  90 nm 
                  90 nm 
                 0 
               
               
                 the Reflective 
               
               
                 layer 
               
               
                 Refractive index 
                 1.6 
                 1.6 
                 1.9 
                 1.9 
                 1.5 
               
               
                 Duty cycle 
                 0.28 
                 0.28 
                 0.37 
                 0.37 
               
               
                 Grating period 
                 130 nm 
                 130 nm 
                 130 nm 
                 130 nm 
               
               
                   
               
             
          
         
       
     
         [0033]    Table VI shows the simulated variables of long-length visible light reflection of the anti-radiation structure  300  with different thicknesses d of the reflective layer  303 . The refractive index of the periodic grating  305  and the reflective layer  303  is 1.6, the grating height H is 70 nm, and grating period is 130 nm.  FIG. 10  shows simulated results of reflection versus wavelength, wherein curves  26 - 29  correspond to #26-29 in Table VI.  FIG. 10  shows that anti-radiation structure  300  with thicker reflective layer  303  has lower reflection to long-length visible red light. 
         [0000]    
       
         
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                   
                 TABLE VI 
               
               
                   
                   
               
               
                   
                 Thickness 
                   
                   
                   
                   
               
               
                   
                 d of the 
                 Grating 
                 Refractive 
                   
                 Grating 
               
               
                   
                 Reflective layer 
                 height H 
                 index 
                 Duty cycle 
                 period 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 #26 (TE) 
                 135 nm 
                 70 nm 
                 1.6 
                 0.28 
                 130 nm 
               
               
                 #27 (TE) 
                 171 nm 
                 70 nm 
                 1.6 
                 0.28 
                 130 nm 
               
               
                 #28 (TE) 
                  99 nm 
                 70 nm 
                 1.6 
                 0.28 
                 130 nm 
               
               
                 #29 
                 0 
                 0 
                 1.5 
               
               
                   
               
             
          
         
       
     
         [0034]    Table VII shows the simulated variables of long-length visible light reflection of the anti-radiation structure  300  with different thicknesses d of the reflective layer  303 . The refractive index of the periodic grating  305  and the reflective layer  303  is 1.9, the grating height H is 60 nm, and grating period is 130 nm.  FIG. 11  shows simulated results of reflection versus wavelength, wherein curves  30 - 33  correspond to #30-33 in Table IV.  FIG. 11  shows that curves  30  and  32  have higher reflection, of about 4% to 11%, to short-length visible blue light. When the thickness d of the reflective layer  303  exceeds 100 nm, the anti-radiation structure  300  (curve  31 ) has lower reflection, to the short-length visible blue light, than substrate  301  (curve  33 ). 
         [0000]    
       
         
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                   
                 TABLE IV 
               
               
                   
                   
               
               
                   
                 Thickness 
                   
                   
                   
                   
               
               
                   
                 d of the 
                 Grating 
                 Refractive 
                   
                 Grating 
               
               
                   
                 Reflective layer 
                 height H 
                 index 
                 Duty cycle 
                 period 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 #30 (TE) 
                 90 nm 
                 60 nm 
                 1.9 
                 0.28 
                 130 nm 
               
               
                 #31 (TE) 
                 121 nm  
                 60 nm 
                 1.9 
                 0.28 
                 130 nm 
               
               
                 #32 (TE) 
                 59 nm 
                 60 nm 
                 1.9 
                 0.28 
                 130 nm 
               
               
                 #33 
                 0 
                 0 
                 1.5 
               
               
                   
               
             
          
         
       
     
         [0035]    Simulated Experiment IV 
         [0036]      FIG. 4  shows an anti-radiation structure  400  for transmission simulation. Variables of Simulated experiment IV include grating height H, refractive index of the substrate  401  and the periodic grating  405  (the periodic grating  405  and the substrate  401  are hypothesized to be same material), duty cycle and grating period T. The incident light of Simulated experiment IV is transverse electric (TE) light, the grating height H is 100 nm, the refractive index of the anti-radiation structure  400  is 1.4, the duty cycle is 0.5, and the grating period is 286 nm.  FIG. 12  shows simulated results of transmission versus wavelength. Curve  34  means zero-order transmission, curve  35  means +/− first order transmission, and curve  36  means total transmission. As shown in  FIG. 12 , the anti-radiation structure  400  of the invention has lower zero-order transmission of 200-400 nm UV light. Unlike Simulated experiments I-III, the principle here is diffraction rather than reflection. By appropriately designing duty cycle, periodic grating  405  of Simulated experiment IV diffracts incident UV light, such that a part of the UV transfer to +/−first order light. As a result, the total transmission of the incident UV light is reduced. 
         [0037]    While the invention has been described by way of example and in terms of preferred embodiment, it is to be understood that the invention is not limited thereto. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.