Retardation compensation element and manufacturing method of the same

Abstract

Two types of layers are simultaneously formed on a substrate and another substrate under the same layer forming condition, the heights of which are equal to a half height of an intended retardation compensation layer. Physical properties of the respective two types of layers formed on the substrates are identical to each other, and if deviations are produced in retardation distribution characteristics for azimuth angles of incident light, these deviations are commonly provided in the respective two types of layers. When one substrate is superposed with the other substrate and these superposed substrates are integrated with each other in order to make a single sheet of retardation compensation element, after one of these substrates is rotated by an angle of 90 degrees with respect to the other substrate, these substrates are stuck to each other by an adhesive agent.

1 . A retardation compensation element comprising:
 a first element including a first transparent substrate, and a first multilayer structure in which at least two types of thin layers that have different refractive indices from each other are alternately stacked on the first transparent substrate;   a second element including a second transparent substrate, and a second multilayer structure in which at least two types of thin layers that have different refractive indices from each other are alternately stacked on the second transparent substrate, the second multilayer structure having a substantially same thickness as that of the first multilayer structure,   wherein the first and second elements have a substantially same retardation distribution characteristic for azimuth angles of light incident on the respective first and second elements,   the first element and the second element are superimposed on each other so that the retardation distribution characteristic of the first element are rotated at substantially 90 degrees relative to the retardation distribution characteristic of the second element for azimuth angles of light incident on the retardation compensation element, and   the retardation compensation element generates negative retardation in light passing the retardation compensation element.   
     
     
         2 . The retardation compensation element according to  claim 1 , wherein the retardation distribution characteristic has a rotational symmetrical pattern of 180 degrees for the azimuth angles of light. 
     
     
         3 . The retardation compensation element according to  claim 1 , wherein the first element and the second element are joined with each other on surfaces of first and second transparent substrates not having the respective first and second multilayer structures. 
     
     
         4 . The retardation compensation element according to  claim 3 , wherein the first element includes an antireflection layer on an uppermost layer of the first multilayer structure, and the second element includes an antireflection layer on an uppermost layer of the second multilayer structure. 
     
     
         5 . The retardation compensation element according to  claim 3 , wherein the first element includes an antireflection layer between the first transparent substrate and the first multilayer structure, and the second element includes an antireflection layer between the second transparent substrate and the second multilayer structure. 
     
     
         6 . The retardation compensation element according to  claim 1 , wherein the first element and the second element are joined with each other on sides thereof having the respective first and second multilayer structures. 
     
     
         7 . The retardation compensation element according to  claim 6 , wherein the first transparent substrate has an antireflection layer on a side thereof not having the first multilayer structure, and the second transparent substrate has an antireflection layer on a side thereof not having the second multilayer structure.