Abstract: A light plate assembly having minimal light leakage and uniform luminosity. The light plate assembly has a housing, a trough within the housing and a cover. The cover has a transparent window with an opaque side edge that prevents undesired light leakage between an outer surface of the transparent window and a base frame of the cover. The transparent window also has a length and a width, and a length-to-width ratio of greater than 10:1. In addition, luminosity variation along a length of the transparent window is less than 20%, and in some instances less than 10%.

Abstract: A filter is disclosed including a four-sided frame having a central aperture therein. Four side walls are provided, with each side wall being pivotally mounted to one side of the frame, and movable between a use position wherein each side wall is substantially perpendicular to the frame, and a storage/shipping position wherein each side wall is substantially parallel to the frame. The filter further comprises a filter member attached to the frame and extending across the central aperture. In the storage/shipping position, the filters are substantially flattened and easily stacked, thereby allowing for efficient storage and ease of transport.