JohnFP wrote:Dave, your points are well recongnized but my statement was that it is EASIER and very possible to make a broadband H1 and not have the missing parts when illuminated with the laser. Broadband does not have to be a white hologram but a 20 or 30 nm swing works quite well and does not increase signficantly the noise in the H2 due to the nature of DCG itself.
I guess narrowband and broadband need to be defined. 1nm? 25nm? 300nm?
In what way is it easier to to make a H2 off an inefficient H1 master? Is it the longer exposure, or easer to make the last alch bath really hot ?is that really easier?
The best advice I can give is to try to make your H1 as narrow band as possible, if that means making the hologram twice the size you need and then cut off the edges, so be it. But if you want to make a very nice H2 with ease, i would suggest starting with a good (color matched) H1 hologram, any other way will just not be as easy ........