G PHYSICS
G01 MEASURING; TESTING
G01B MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
G01B11/00 Measuring arrangements characterised by the use of optical techniques
G01B11/02 for measuring length, width or thickness
G01B11/06 for measuring thickness; ; e.g. of sheet material
G01B11/0683 measurement during deposition or removal of the layer