The arrangement As discussed above

The arrangement As discussed above light delivered to illuminate SLMs 15 may be folded by a fold angle β relative to light beams 12 that are delivered to an image plane 13. Fold angle β may be in a different plane from angle α by which beams 12 converge. The fold by angle β can facilitate making the location at which beams 12 converge on image plane 13 to be physically separated from light beams which deliver light to SLMs 15 (e.g. beams 53 or 56).