This mod shows how the 405-G-1 glass lens was altered for Blu-ray. The glass lens has a small aperture sleeve/retainer which provides help in focusing the light. The 405-G-1 glass lens also provide a 31% increase in Blu-ray power.
The Aspheric lens is used by the 405-G-1 glass lens with both sides having AR coating. There will be some expense on the parts since the machine work for modification and custom space do not contribute a lot. The assembled lens mod is included with the modification of the 405-G-1 glass lens along with focus ring.
You are free to do this mod or just buy the finished product for convenience.