OPTICAL MEASUREMENTS OF SUBSTRATES FOR LIQUID-CRYSTAL DISPLAYS

Two optical measurement techniques and set-ups for the optical and so forceless measurement of flatness deviation and macrowaviness on the o ne hand and of microwaviness of large thin panes on the other hand are described. The first set-lip uses an triangulation arrangement with a telecentric grazing incidence illumination in connection with a CCD-l ine camera and a controlled linear stage. The second set-up for the me asurement of the microwaviness is based on a Mach-Zehnder interferomet er that eliminates the influence of the backside reflection on the int erference pattern due to an oblique incidence of light with an extende d light source. The experimental results demonstrate the possibilities of the presented measurement techniques.