accomplish the desired results of the present invention it is preferred to locate the slitted mask 82 so that it is imaged by the spherical mirror 83 at the plane of the light valve array 85 therefore the slit is preferably located somewhere between the focus and the radius of curvature of the spherical mirror 83 it should also be noted that in order to maintain the source 81 and bimorph mirror 84 as conjugates the source should be positioned beyond the radius of curvature of mirror 83 whereas the driven scan mirror 84 should be positioned within the radius of curvature of that mirror this is desirable in order to compensate for any additional pathlength introduced by the reflection from the flat mirror 86 in some constructions similar to the fig8 embodiment e g when long light valve arrays are used an undesirable component to the scan is evident at the image plane this can result because the scan axis of the bimorph mirror is not colinear with the light valve array direction and the scanning occurs along the arc of a circle instead of along a line the effect is most noticeable in images of the light valves at the extreme ends of the array and the modified embodiment shown in fig9 and 10 can be employed to eliminate this problem in such modification the final illumination path to the scan mirror is collinear to the scan axis since the array must be imaged the last time the light reflects across the scanning mirror a.