Hey !
I just realized an obvious and cruel truth.
I won't be able to record satisfying holograms on this HOLO 250 PAR film with my HeNe laser !
The Holo film is designed to be sensitive in the very narrow area of 694nm (meant to be used with pulsed ruby) where my HeNe is most likely around 632nm :
- wavelenghts.jpg (751.32 KiB) Viewed 15662 times
This also explains why the exposure with a laser LED works better, the led must be some "InGaAlP" diode which emits somewhere between 630-685, probably in my case nearer to 685.
When reading the wonderful document shared by Ed here :
http://edweslystudio.com/Materials/AgX/ ... 150186.pdf I can read that by this time Illford preconised to chemically process the "master holograms" which were recorded in 632 so that they would be shifted toward 694 for easier copy. (the holo 250 par film was used in holocopier).
So, as I don't intend to record a master transmission hologram (yet) then shift it 60nm up, i wonder if there would be any way to somehow shift sensitivity of the film closer to 630nm ? some undying maybe ? anyone heard of such thing ? I know we can pre-swell films somehow, would that help ?