APPARATUS AND METHOD FOR THIN FILM FORMATION AND OPTICAL FILM THICKNESS MONITORING DEVICE

PROBLEM TO BE SOLVED: To improve the yield, while coping with mass production requirement, in a vacuum film formation process of producing an optical filter.SOLUTION: A thin film formation apparatus comprises: a film formation chamber; a film formation material feeder provided in the film formation chamber; a substrate holder which is arranged in the film formation chamber, holds a plurality of to-be-film-formed substrates in such a way that the film formation surface faces the film formation material feeder, has a dome- or flat-disk shape and is rotated, with the top of the dome or the center of the flat disk as the rotation center; a light projection part which projects monitor light onto the to-be-film-formed substrate held in the outer peripheral part of a substrate holder; a light-receiving part which receives the monitor light transmitted by the to-be-film-formed substrate and outputs light reception signals; a trigger signal outputting part which outputs trigger signals, synchronized with the rotation of the substrate holder; and a signal processing part which is inputted with the light receiving signals and the trigger signals and processes the light reception signals and the trigger signals to acquire a light transmittance for each to-be-film-formed substrate.