| 摘要 |
PURPOSE:To compensate the variance of spectral sensitivity for a sensor itself, by providing a multi-layer film filter having varied in thickness consecutively in the direction vertical to a line at a place near the photodetecting surface of a line sensor, in a picture reader. CONSTITUTION:A multi-layer film filter 8 having varied in thickness uniformly in a single direction for alternating layers 2'-7' on a substrate 1' is produced with control of its thickness by a vacuum vapor deposition process. The characteristic curves of A'-C' of the multi-layer film filter are shown like A-C respectively. An original 11 is scanned in the direction of an arrow F and formed into an image on the photodetecting surface of a CCD9 through an image forming lens 10. The photodetecting surface of the CCD9 is formed in a line rectangularly in the secondary scanning direction F. Thus the original 11 is successively read. When the filter 8 is set near the CCD9 and shifted in the direction of an arrow D or E, the characteristics can be changed like A-C. This never deteriorate the image forming performance of the lens 10. |
