I made a DCG master a few weeks ago.
I went and shot an H2 the other night.
Normally I take the master and flip it so that when shooting an H2 the pseudo image is facing up. Then spray paint the non pseudo side of the master black.
I must have been tired and had accidentally spary painted the pseudo side and made some contact copies of it. They turned out OK but the realized my boo boo.
In making contact copies do you still use the pseudo side of the master or is that just for image plane stuff.
Thanks all and have a good weekend!!
DCG Master Question
-
Dinesh
DCG Master Question
It depends where you want your final image.
When you make a single-beam Denisyuk, the object is behind the plate - the front being the reference beam side - and the reconstruction beam diffracts "outwards". In other words, the object beam is diverging and the image is virtual. If you contact copied by having the back end of the original, the master, downwards and placed the copy plate on the front - what you call the non-pseudo side - then the object beam from the master will diverge and the hologram will capture an object that is apparently behind - underneath? - the master plate. You've effectively created another master but put the image even further away from the plate than the original, by the copy plate-master plate distance.
If you turned the master plate over and placed the plate front end downwards with the copy plate on the back side - what you call the pseudo side - then the object beam will converge to a real image. If you displaced the copy plate by the distance between the original master and the original image, you'd get an image-planed hologram.
Now you have to worry about the direction of the second reference. If you get that wrong, you'll end up with an upside down image!
When you make a single-beam Denisyuk, the object is behind the plate - the front being the reference beam side - and the reconstruction beam diffracts "outwards". In other words, the object beam is diverging and the image is virtual. If you contact copied by having the back end of the original, the master, downwards and placed the copy plate on the front - what you call the non-pseudo side - then the object beam from the master will diverge and the hologram will capture an object that is apparently behind - underneath? - the master plate. You've effectively created another master but put the image even further away from the plate than the original, by the copy plate-master plate distance.
If you turned the master plate over and placed the plate front end downwards with the copy plate on the back side - what you call the pseudo side - then the object beam will converge to a real image. If you displaced the copy plate by the distance between the original master and the original image, you'd get an image-planed hologram.
Now you have to worry about the direction of the second reference. If you get that wrong, you'll end up with an upside down image!
DCG Master Question
I would agree with Dinesh as well. it doesn’t really matter which way as long as it replays well in the laser light. i would say if your master was weak it would be better to have you master focus image wave front into the film plate rather than to simply make a contact copy as the object light is not focused into the film .
When researching dcg I had a very bright Polaroid hologram i would simply lay my test plate on it and it and expose, this would replicate the hologram easily every time (even with only a couple mins of settle time).
When researching dcg I had a very bright Polaroid hologram i would simply lay my test plate on it and it and expose, this would replicate the hologram easily every time (even with only a couple mins of settle time).