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...and that's how we prove that white-light holograms aren't holograms. (Credit-card holograms function just like scratch-holograms, and their 3D image is not

by wbeaty 10y ago

...and that's how we prove that white-light holograms aren't holograms. (Credit-card holograms function just like scratch-holograms, and their 3D image is not created via diffraction.) [Are these REALLY holograms?](http://amasci.com/amateur/holo3.html http://amasci.com/amateur/holo3.html)

dTal 10y ago
Interesting. I never quite grokked rainbow holograms, so perhaps there's something in that. But it's unfair to say all white-light holograms aren't holograms. A normal Denisyuk reflection hologram made with lasers and everything will replay perfectly well under a halogen lamp.
- wbeaty 10y ago
  > I never quite grokked rainbow holograms, If you made a scratch hologram, but your compass-point had a small cluster of fifty tiny needles instead of a single big needle, that comes close to the fringe-structure of Benton white-light holograms. :) > But it's unfair to say all white-light holograms aren't holograms True. By "white light" I was referring to Rainbow / credit-card / Benton holograms.
mhalle 10y ago
You are referring to stamped foil or embossed holograms such as the ones used as security marks on credit cards. Here's a description of the process: http://www.holoeast.com/holography/holograms_maiking.html http://www.holoeast.com/holography/holograms_maiking.html Inspired by the process for creating compact disks, stamped holograms took Benton's rainbow holograms and made them cheaply reproducible through a mechanical process. Mike Foster developed the process and Steve McGrew made it commercially viable. Other types of white light holograms, such as the two-step "rainbow" white light transmission hologram that Steve Benton created or the white light reflection hologram of Yuri Denisyuk are both holograms proper -- they are both made using a traditional holographic process. A transmission white light hologram has less controllable color because it uses broad spectrum diffraction. A white light reflection hologram uses a thick diffraction pattern to additionally filter white light down to a narrow spectrum, producing a more pure color. Full color reflection holograms can be produced by superimposing multiple diffractive patterns in the hologram layer, one for each primary color.

by wbeaty 10y ago

dTal 10y ago

Interesting. I never quite grokked rainbow holograms, so perhaps there's something in that. But it's unfair to say all white-light holograms aren't holograms. A normal Denisyuk reflection hologram made with lasers and everything will replay perfectly well under a halogen lamp.

wbeaty 10y ago
> I never quite grokked rainbow holograms, If you made a scratch hologram, but your compass-point had a small cluster of fifty tiny needles instead of a single big needle, that comes close to the fringe-structure of Benton white-light holograms. :) > But it's unfair to say all white-light holograms aren't holograms True. By "white light" I was referring to Rainbow / credit-card / Benton holograms.

mhalle 10y ago

You are referring to stamped foil or embossed holograms such as the ones used as security marks on credit cards. Here's a description of the process: http://www.holoeast.com/holography/holograms_maiking.html http://www.holoeast.com/holography/holograms_maiking.html Inspired by the process for creating compact disks, stamped holograms took Benton's rainbow holograms and made them cheaply reproducible through a mechanical process. Mike Foster developed the process and Steve McGrew made it commercially viable. Other types of white light holograms, such as the two-step "rainbow" white light transmission hologram that Steve Benton created or the white light reflection hologram of Yuri Denisyuk are both holograms proper -- they are both made using a traditional holographic process. A transmission white light hologram has less controllable color because it uses broad spectrum diffraction. A white light reflection hologram uses a thick diffraction pattern to additionally filter white light down to a narrow spectrum, producing a more pure color. Full color reflection holograms can be produced by superimposing multiple diffractive patterns in the hologram layer, one for each primary color.