Layer system and optical element comprising a layer system

Abstract

A layer system includes at least one stack of successive multilayers, wherein each multilayer includes a first partial layer with a first optical thickness and a second partial layer with a second optical thickness that is different from the first optical thickness. The multilayer has optical characteristics that are specified depending on a parameter which is a function of a ratio of quotients of the optical thickness of a partial layer with higher refractive characteristics and the optical thickness of a partial layer with lower refractive characteristics of the respective multilayers, wherein the index i denotes the order of the successive multilayers in the stack. The product of a reflectivity of the stack of multilayers and the parameter is less than for an anti-reflection and/or anti-reflective effect of the stack of multilayers, or is greater than or equal to 1 for a mirroring. An optical element may include a layer system and a method for producing such a layer system.

1 . An interferometric layer system platform for optical elements, comprising:
 at least one stack of successive multilayers, wherein each multilayer comprises a first layer with a first optical thickness and a second layer with a second optical thickness that is different from the first optical thickness, the optical thickness being (d/λ)*n where d is a layer thickness, λ is a design wavelength and n is an index of refraction for the layer,   wherein the multilayer has optical characteristics that are specified depending on a parameter which is a function of a ratio of quotients v i  of the optical thickness of a layer with higher refractive index and the optical thickness of a layer with lower refractive index of the respective multilayers, wherein the index i denotes the order of the successive multilayers in the stack, wherein the partial layer with higher refractive characteristics comprises in particular a high-refractive partial layer and the partial layer with lower refractive characteristics comprises in particular a low-refractive partial layer, and   wherein the product of a reflectivity of the stack of multilayers and the parameter is less than 1 for an anti-reflection and/or anti-reflective action of the stack of multilayers, or is greater than or equal to 1 for a mirroring.   
     
     
         2 . The layer system platform according to  claim 1 , wherein the parameter for a stack of three or five successive multilayers is 
       
         
           
             
               σ 
               = 
               
                 
                   v 
                   1 
                 
                 
                   
                     ∑ 
                     
                       i 
                       = 
                       2 
                     
                     nmax 
                   
                    
                   
                     v 
                     i 
                   
                 
               
             
           
         
         wherein i=1 to nmax, for nmax=3 or nmax=5, denotes the order of the multilayers in the stack, and vi results from a quotient of the optical thickness of the partial layer with higher refractive characteristics relative to the optical thickness of the partial layer with lower refractive characteristics of a respective multilayer. 
       
     
     
         3 . The layer system platform according to  claim 1 , wherein the parameter for a stack of four successive multilayers is 
       
         
           
             
               σ 
               = 
               
                 
                   
                     v 
                     1 
                   
                   + 
                   
                     v 
                     2 
                   
                 
                 
                   
                     v 
                     3 
                   
                   + 
                   
                     v 
                     4 
                   
                 
               
             
           
         
         wherein the digits 1 to 4 denote the order of the multilayers in the stack, and vi with i=1 to 4 results from a quotient of the optical thickness of the layer with higher refractive characteristics relative to the optical thickness of the partial layer with lower refractive characteristics of a respective multilayer. 
       
     
     
         4 . The layer system platform according to  claim 1 , wherein the layers with lower refractive indices and layers with higher refractive indices are arranged in the multilayers of the stack in the same order in each case. 
     
     
         5 . The interferometric layer system platform according to  claim 1 , wherein the stack of multilayers has an anti-reflective effect if the parameter is set to less than 4. 
     
     
         6 . The interferometric layer system platform according to  claim 1 , wherein a difference between the index of refraction of the first layer and the second layer in the same multilayer is greater than 0.2. 
     
     
         7 . The interferometric layer system platform according to  claim 1 , wherein the first layers have a first index of refraction of at least 1.6, and the second layers have a second index of refraction of at most 1.5. 
     
     
         8 . The interferometric layer system platform according to  claim 1 , wherein the respective last multilayer of the stack of multilayers has a a low-refractive functional layer between the first layer and second layer. 
     
     
         9 . The interferometric layer system platform according to  claim 1 , wherein within the stack of multilayers the layers with lower refractive indices are formed from the same material, and wherein within the stack of multilayers the layers with higher refractive indices are formed from the same material. 
     
     
         10 . The interferometric layer system platform according to  claim 1 , wherein the first layers include at least one of the materials Ta 2 O 5 , TiO 2 , ZrO 2 , Al 2 O 3 , Nd 2 O 5 , Pr 2 O 3 , PrTiO 3 , La 2 O 3 , Nb 2 O 5 , Y 2 O 3 , HfO 2 , ITO, Si 3 N 4 , MgO, CeO 2  or an oxidation stage of these materials. 
     
     
         11 . The interferometric layer system platform according to  claim 1 , wherein the second layers include at least one of the materials SiO 2 , SiO, silanes, siloxanes. 
     
     
         12 . The interferometric layer system platform according to  claim 1 , wherein a layer system is provided on two opposing surfaces of the substrate to form a two layer system. 
     
     
         13 . The interferometric layer system platform according to  claim 8 , wherein the two layer systems have a different number of multilayers. 
     
     
         14 . The interferometric layer system platform according to  claim 1 , wherein the at least one surface of the substrate is coated with a hard layer.