| 摘要 |
PROBLEM TO BE SOLVED: To solve the problems wherein, in a film thickness measuring device for irradiating a film having a thickness to be measured with light, determining a power spectrum from a spectrum of reflected light or transmitted light, and calculating the film thickness, since a widely different measured value is frequently acquired from a material having a thick haze such as polypropylene or polyethylene, the measurement is difficult, and since measured values are widely dispersed by tilt or crease of the film, the device is difficult to be used as an online thickness meter. SOLUTION: A measured quality such as a peak height, a peak area, a reflectance or the like of a power spectrum is calculated, and the measured quality is compared with a threshold to determine validity/invalidity of measurement, and a film thickness measured value is outputted to the outside only in the case of validity. Since widely different measured values can be removed, the reliability of the measurement is improved, and the measurement of the film thickness of polyethylene or the like which has been difficult to be measured hitherto is provided. COPYRIGHT: (C)2011,JPO&INPIT
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