Abstract
This paper presents an industrial application of a new type of graphic technique based on dual two-dimensional optical system and video image analysis. The technique has been intensively developed for optical fiber industry for preform inspection held beforehand fiber drawing. The optical system uses a pair of LCD and CCD video camera both as two-dimensional detector and as two-dimensional light source, respectively, to achieve dual two-dimensional co-ordinations required in its principle. For corresponding to various type of fiber preforms, we can choose suitable method from some variations of measurement technique which each uses different type of pattern on LCD and its virtual movement. The CCD image is numerically processed and refractive index distribution in the sample preform is finally reconstructed for assessment of fiber quality. The equipments based on the method have been practically constructed and the principles are successfully confirmed by experiments.
