Flatness tester for optical components

摘要

Disclosed herein is a method comprising capturing an image of a grating formed on a surface of a brightness enhancing display film; measuring a displacement Deltad of a fringe from the image of the grating; and determining a slope of a deviation from flatness of the brightness enhancing display film from the displacement Deltad by using the equation (I) $\begin{array}{cc}\mathrm{Delta}d\left(y,{\mathrm{theta}}_2\right)=2y\sin \left({\mathrm{theta}}_1+{\mathrm{theta}}_3-2{\mathrm{theta}}_2\right)\left[\frac{\tan \left({\mathrm{theta}}_1+{\mathrm{theta}}_3-{\mathrm{theta}}_2-90\right)}{\begin{array}{c}\tan \left(90-{\mathrm{theta}}_2\right)+\\ \tan \left({\mathrm{theta}}_1+{\mathrm{theta}}_3-{\mathrm{theta}}_2-90\right)\end{array}}\right]& \left(I\right)\end{array}$ wherein y represents a distance along the brightness enhancing display film that represents a location of the deviation from flatness; theta₁ is a light box angle; theta₂ is the slope of the deviation from flatness in the brightness enhancing display film; and theta₃ is a camera angle.