| 摘要 |
<p>An electronic imaging system includes an optical system (12) for imaging radiation from a scene onto the image sensing surface (22) of an imaging device (14) for a selected sample period. The imaging device may take the form of a two dimensional array of photoresponsive areas having a device specific upper spatial frequency limit. In order to eliminate alias signal components in the output video signal caused by spatial frequency components in the scene radiation greater than the Nyquist spatial frequency of the device, the optical system (12) is designed to have a spatial frequency limit no higher than the Nyquist frequency of the imaging device and thus functions as a low pass optical filter. The spatial frequency response of the optical components can be controlled by controlling the rotationally symmetric aberrations, and in the preferred form, higher order terms, third and above, which contribute to the spherical aberration of a lens system are designed to have balancing non-zero values to provide the necessary characteristics of the modulation transfer function of the optical system.</p> |
