| 摘要 |
An apparatus and a method for inspecting film defects are provided to fine film unevenness exactly, generated by cross of an optical axis of the film, based on light transmitted through a film. An apparatus(10) for inspecting film defects comprises a couple of polarizing plates(18,19), a light source(15), a light receiver(16) and a determining device(21). The polarizing plates are disposed to be crossed nicols at both sides of a film, and are parallel to front and rear surfaces of the film. One polarizing transmission axis is approximately parallel to a slow axis of the film. The light receiver is disposed at an opposite side of the film to the light source, firstly receives light projected from the light source and transmitted through the film and the other one of the polarizing plates, and then outputs a photoelectric signal corresponding to the received light. The determining device performs determination based on the photoelectric signal from the light receiver with respect to presence of defects of the film. Theta 1 represents an angle formed between an optical axis of the light receiver and a normal line that is perpendicular to the surfaces of the film, and theta 2 represents a rotational angle formed between the optical axis and a reference line that is orthogonal to the slow axis of the film. The light receiver is positioned to satisfy the following conditions. 15[deg.]<=[theta]1<=35[deg.], 20[deg.]<=[theta]2<=60[deg.].
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