| 摘要 |
PURPOSE:To detect a signal level with bias light by providing an optical filter which transmits a bias illumination light only and does not transmit a light wavelength region from an object to at least a part of an electron beam scanning section at the outside of an image pickup plane effective part. CONSTITUTION:The emission spectrum characteristics of the image pickup tube 1 is shown in Curve I and a bias light characteristics of a bias light source 6 is shown in Curve II. In providing a bias light detecting optical filter 4 having a spectral transmission shown in Curve IIIA or IIIB onto a photoelectric converting plane 3, most of the bias light transmits, but green light from the image pickup tube 1 is shut completely. As a result, a signal from the photoelectric converting plane corresponding to the filter 4 exists based on the bias light only, and since the image pickup light and the bias light coexist on the effective image pickup part, the residual image reduction by bias light is attained, and when the amount corresponding to the ineffective image pickup part is calculated and eliminated from the signal level, the video signal only with the image picked-up light only is obtained. |
