Light blocking stop for electro-optic line printers

In an electro-optic printer having a multigate light valve for serially phase front modulating a sheet-like collimated light beam in accordance with picture elements for successive lines of an image so that the modulated light beam includes zero order and higher order diffraction beams, a photosensitive recording medium, and Schlieren imaging optics optically aligned between said light valve and said recording medium for sequentially exposing said recording medium to successive lines of said image;

• said imaging optics having an aperture including a stop configured to substantially attenuate a selected one of either the zero order or the high order diffraction beams of said modulated light beam while causing relatively little attenuation of the other of said zero order or said diffraction beams, the improvement wherein said stop comprises:
• an opaque member having a pair of spaced axially aligned slit-like apertures through which said other of said zero order or said diffraction beams pass to expose said recording medium,
• the portion of said opaque member laying between said aperture pair forming a beam stop for substantially attenuating said one of said zero order or said diffraction beams,
• the sides of said beam stop defining the interior adjoining walls of each one of said aperture pair,
• said beam stop sides being smoothly tapered in complementing relation with one another.