As I understand it, the concept of multicoating was originally developed by NASA. Their process for generating an even coat of the desired angstroms thickness was unbelievably difficult and costly, but it did demonstrate the effectiveness of multiple coatings to match the impedance of free space to that of glass across the visible spectrum. Matched (complex conjugate) impedance is required for maximum transmission. As I understand it (could be wrong), it was Asahi Optical that developed and patented the current process that makes such accurate coatings mass producible. I further understand that (at least for some time), companies that desired to produce accurate multicoatings paid a royalty to Asahi Optical. Some companies elected to license only a part of the process, others decided to go their own way.
From: "Alan Chan" <[EMAIL PROTECTED]> > >http://www.photozone.de/canonFAQ.htm#3Q4c > > And that makes me wondering, is good coating so difficult or expensive to > develop that even big player like Canon could not do it? - This message is from the Pentax-Discuss Mail List. To unsubscribe, go to http://www.pdml.net and follow the directions. Don't forget to visit the Pentax Users' Gallery at http://pug.komkon.org .
