Novel corrective machining method to fine-tune groove widths

Using lenticular lenses to realize auto-stereoscopic displays has become increasingly popular in the TV industry, especially in the area of developing multi-view glasses-free 3D TV. Each lenticular lens has many sublenses through which the light is diverted in different directions. A multi-view TV display projects a vertically rotated 3D image to a viewer that seamlessly matches his or her sideways movement. To do so, it poses a very stringent requirement on machining lenticular lens mold. Using a tailor-made cutting tool, the profile of the lenticular grooves can be machined very precisely, and in a very efficient manner; however, the groove width might vary due to elastic bouncing. Such variation of the groove width leads to disparity in the light intensity entering the left and right eye of the viewer. The 3D perception would then unavoidably deteriorate. Thus, a corrective machining method must be developed to fine-tune the groove width. In this paper, a method involving transverse cutting perpendicular to the axes of the lenticular grooves is proposed, in which the cutting is done transversely across the grooves using a single point diamond tool. The depth of corrective cut is 1 μm, and the errors in the groove widths can be corrected to ±200 nm.