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Hologram Laser Questions

kecked

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Joined
Jun 18, 2012
Messages
822
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63
Thank you for your comments and images. They were very educational and enjoyable. I’ve never tried holography but have always enjoyed watching the process.
 



18LJ

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Joined
Oct 31, 2017
Messages
66
Points
18
All holograms record information down to microscopic resolution. It's the replay light that determines the resolution of the images replayed. I'm using an obsolete Ikea Jansjo LED clamp-based lamp to replay the holograms above. It's still available on Ebay, and is the absolute best light ever for lighting holograms (other than laser). The currently available Jansjo is USB-powered and way too dim.

The cannabis hologram "master" was made with a pulsed frequency-doubled Nd:YLF laser giving green light in a 30ns pulse of about 700mJ. What's seen above is a hologram of that master hologram, shot with a 35mW red He-Ne laser and processed to replay in green.

Hologram and scene size is generally determined by the size of the optical table used to make the hologram. Some images are originally captured with conventional photography and made into a "master" hologram with a process camera built on a large optical table. Similar to a lenticular 3D photograph, but without the need for a plastic lenticular lens in front like on those old postcards.
Interesting thanks for the info. I wasnt aware you could make them out of photos.
 

Eidetical

Active member
Joined
May 14, 2022
Messages
135
Points
43
This hologram I produced in the mid-'90s was made from 450 computer generated photographs made by Brian Kane. It's 3D horizontally because there are 30 perspective views of the stack of TVs. It's 3D vertically because there are 15 perspective views in that direction. The master hologram was a 15x30 grid of exposures on a 32x43cm plate.

The images on each of the TVs change with 15 steps of animation as one pitches the hologram back and forth. This was apparently the first full-parallax integral hologram published. OJ's white ford Bronco is in the top right corner. Crash test dummy in the bottom fight corner. Brian was/is the artist.

TV on Cover.JPG
 

Eidetical

Active member
Joined
May 14, 2022
Messages
135
Points
43
Made another hologram of my bunny yesterday, using a 33 mW Spectra-Physics model 127 He-Ne. The beam encountered two aluminum mirrors, 20x microscope objective, 25 micron pinhole, 25" path length to the plate off a large aluminum mirror, 38 degrees reference angle, p-polarization, bunny's nose is 4" from the plate, and a 6" path length mismatch (at the nose) with around 12" of coherence from the laser. The reference beam power at the plate was 0.05 mW/cm^2 with a beam ratio of 10:1, and I gave it 30 mJ/cm^2 with a 10 minute exposure after a 10 minute settling period.

He's waaaay dimmer than my previous results, but power and exposure were both much lower, and fringe visibility was much worse because of the limited coherence length of the laser when used in this type of set-up. Still a magical hologram!

Bunny Red.jpg
 




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