Diffraction-type 3d display element and method for fabricating the same

Abstract

A diffraction-type 3D display element is arranged on an image output face of a 3D display device and comprises a first diffraction area and a second diffraction area. The first diffraction area has a plurality of first stepped gratings spaced apart from each other. The second diffraction area has a plurality of second stepped gratings spaced apart from each other. The second diffraction area is adjacent to the first diffraction area and is arranged symmetrically to the first diffraction area with a central line being the symmetric axis. The diffraction-type 3D display element of the invention diffracts the images output by the 3D display device and projects the diffracted images to two different viewing areas to provide 3D images for users.

1 . A diffraction-type 3D display element, arranged on an image output face of a 3D display device, comprising
 a first diffraction area including a plurality of first stepped gratings spaced apart from each other and each including a first stepped incline;   a second diffraction area being adjacent to the first diffraction area and including a plurality of second stepped gratings spaced apart from each other and each including a second stepped incline, the second stepped gratings being arranged symmetrically to the first stepped gratings with a central line being a symmetric axis.   
     
     
         2 . The diffraction-type 3D display element according to  claim 1 , wherein the first diffraction area and the second diffraction area are respectively corresponding to a left-eye image output area and a right-eye image output area of the 3D display device. 
     
     
         3 . The diffraction-type 3D display element according to  claim 2 , wherein normals of the first stepped inclines and the second stepped inclines go far away from the central line. 
     
     
         4 . The diffraction-type 3D display element according to  claim 1 , wherein there are a plurality of first diffraction areas and a plurality of second diffraction areas, and wherein the first diffraction areas and the second diffraction areas are arranged alternatively. 
     
     
         5 . A method for fabricating a diffraction-type 3D display element, comprising steps:
 cleaning a substrate;   undertaking a first etching process, wherein the first etching process employs a first mask to form a plurality of first flattened areas and a plurality of first recessed areas on the substrate;   aligning a second mask, wherein the second mask is aligned to borders of the first flattened areas and the first recessed areas; and   undertaking a second etching process, wherein the second etching process employs the second mask to form second recessed areas on the first flattened areas and the first recessed areas respectively, and wherein each second recessed area is formed at a depth smaller than that of the first recessed area to form a four-step structure.   
     
     
         6 . The method for fabricating a diffraction-type 3D display element according to  claim 5 , wherein the depth of the second recessed area is half the depth of the first recessed area. 
     
     
         7 . The method for fabricating a diffraction-type 3D display element according to  claim 5  further comprising steps:
 aligning a third mask, wherein the third mask is aligned to borders of the first flattened areas, the first recessed areas and the second recessed areas; and 
 undertaking a third etching process, wherein the third mask is used to undertake the third etching process to respectively form third recessed areas on the first flattened areas, the second recessed areas in the first flattened areas, the first recessed areas, and the second recessed areas in the first recessed areas, and wherein each third recessed area is formed at a depth smaller than that of the second recessed area to form an eight-step structure. 
 
     
     
         8 . The method for fabricating a diffraction-type 3D display element according to  claim 7 , wherein the depth of the third recessed area is half the depth of the second recessed area.