| 摘要 |
<p>A band-limiting filter 24b of the invention exhibits a trimodal filter characteristic, and includes, for example, band-limiting transmittance filter characteristic portions Rb, Gb, and Bb for wavelength regions of red, green, and blue, respectively. More specifically, the band-limiting transmittance filter characteristic portions Rb, Gb, and Bb, for example, have bandpass characteristics in which the respective center wavelengths are 630 nm (full width at half maximum »1 =30 to 90nm), 540nm (full width at half maximum »2 =20 to 60nm), and 440nm (full width at half maximum »3 =50 to 80nm). This makes it possible to obtain an image of a predetermined color tone by restraining an influence of spectral sensitivity characteristic of an image pickup device when the band-limiting filter is applied to a synchronous type endoscope for performing color image pickup to perform observation under normal illumination light.</p> |
