During a Glass Expert run, CODE V may replace NSF6 on a surface with NSF6HT and perform a few optimization cycles. Although the glass change itself produces no difference in the ray trace, the additional optimization cycles may improve the design. Glass Expert detects the improvement, and attributes it to the material replacement. This “new” material signals Glass Expert to re-evaluate the materials on the other surfaces of the lens, extending the time for Glass Expert to complete.
The HT, HTUltra, and W glasses have higher transmission than their ordinary counterparts. Since Glass Expert can include a transmission criterion, which version of the glass should you include in your custom catalog? We suggest that you keep only the highest transmission version of each glass in your glass set (e.g., drop NSF6 and NSF6HT, but keep NSF6HTUltra; drop F2, but keep F2HT.) When you run Glass Expert with that glass set, the final design might include some HT or HTUltra glasses. If so, hand-substitute the ordinary glass for the high transmission version on one surface and run the Transmission Analysis option. If the transmission is acceptable, you can use the standard version of the glass on that surface. Repeat the process of replacing each HT glass with its ordinary version, running Transmission Analysis, and determining if the transmission is adequate for each remaining high transmission material. The Transmission Analysis option evaluates quickly, and you will know that any high transmission materials that remain in your system are needed.