| 摘要 |
<p>PURPOSE:To improve the picture quality by setting a main diaphragm on the image forming surface of an image pickup lens and varying the aperture size of the main diaphragm to change the width of a scanning line. CONSTITUTION:A main diaphragm 4 is set on the image forming surface of an image pickup lens 3, and the diaphragm 4 functions as a viewfield diaphragm. An optical system 10 provided between the diaphragm 4 and a photomultiplier 5 leads a luminous flux to the photodetecting surface of the photomultiplier 5 in the form of approximately parallel beams, and therefore the photodetecting region has no change although the aperture size of the diaphragm 4 is varied. Then a focal point F is coincident with the position of the diaphragm 4. The beams given from any position on the scanning line become parallel beams after passing through the system 10 and reach the photodetecting surface of the photomultiplier 5 in an even distribution. This stabilizes the working of the photomultiplier 5 and then improves the quality of recorded pictures.</p> |
