Asahi-dow Limited

Shingo Ishikawa

Akitaka Yasujima

Naoyuki Shiratori

An infrared light is applied to a polymer film having a thickness of less than 30.mu., and the infrared light is spectroscopically separated before or after being applied to the polymer film to obtain an infrared interference fringe spectrum based on the polymer film, and then the extreme points of the infrared interference fringe spectrum are detected by processing, whereby to measure the thickness of the polymer film.

Infrared interference type film thickness measuring method and

A method and an apparatus for measuring the thicknesses of film layers of different synthetic resins forming a composite multilayer film or sheet by utilizing infrared rays. Infrared rays of sample wavelengths, each equal to the infrared absorption wavelength of each film layer, and at least one reference wavelength different from the infrared absorption wavelength of each film layer are projected onto the multilayer film to be measured. Ratios are obtained between the amounts of infrared lights of the sample and reference wavelengths transmitted through the multilayer film. An operation is achieved for solving a simultaneous equation including the ratios and the infrared absorption coefficients of the film layers at the sample and reference wavelengths as coefficients and the thicknesses of the film layers as unknowns, thereby obtaining the thicknesses of the film layers.

Growing community of inventors

Kawasaki, Japan

Shingo Ishikawa