Device for measuring light absorption characteristics of a thin film spread on a liquid surface, including an optical device

摘要

A film forming device includes an optical device which has a light source, and a first optical system for projecting light beams split by a light splitting device. The light splitting device and the optical system steadily maintain the intensity center of the light beam projected onto a detecting surface of a light detector at an invariable position without positional fluctuation independently of fluctuation of an emitting angle to a thin film of the light source.