Product Announcement from National Photocolor Corp.
NPC Standard Pellicle Frames are stocked in 1",2",3",4",5" and 6" circular rings, plus 5"x7" rectangles. Top surfaces are beveled. The frame is black anodized, then lapped to create a flat at the inner edge.
The membrane is then stretched over the flat and firmly adhered to the beveled area. The machined aluminum rings have two threaded mounting holes on the back.
National Photocolor offers seven (7) standard frames and we routinely mount pellicles on custom frames. Frames, which should be designed in conjunction with NPC, may be supplied by the customer or National Photocolor. Frequently, a frame can be quickly and inexpensively supplied from our large inventory of special frames.
Custom pellicles have been made from 1/16" I.D. to 16" I.D. In addition to circles and rectangles, ellipses and truncated cylinders (tubes cut off at an angle) are used for their ability to pass a circular beam at 45°
Custom frame design is usually similar to standard design, although cross sections may be altered and the bevels varied or eliminated.
Though flatness of standard pellicles is suitable for most uses, some applications require unusual flatness. The flatness of the reflective surface is mainly dependent upon the flatness of the lapped area. Special frames may be manufactured for the most demanding applications. For best results, frames should generally be circular and slightly oversized to allow edge aberrations to "iron out" outside the critical central area.
Extra-flat frames may require larger cross-sections and may be machined of stainless steel ceramic, or other materials. In use, flat pellicles must be installed carefully to prevent distortion of the frame. Systems should be designed so that the more critical beam is transmitted, rather than reflected.
Uniformity of transmission and flatness on reflection can be documented on request.