Electrophotographic film question

jsmoove · Jul 12, 2017

Reading this here: http://rm.sc.gov/leaflets/Documents/SEVEN.pdf
And I came across this blurb under electrophotographic film:
"This film is unique because the fiche can be updated. Images can be deleted and added after the fiche is made; in addition, one brand of camera can be used to remove an image and replace it with another."
What exactly are they talking about? What kind of camera would be able to do this?

Thanks

AgX · Jul 12, 2017

Link does not work.

jsmoove · Jul 12, 2017

Weird..it works for me! Ive uploaded the pdf to imgur: http://imgur.com/a/sqsVm
I think they mean a xerocamera, but im not finding much info on this...http://imgur.com/a/PcUfj

AgX · Jul 12, 2017

Without knowing your source all I can say that it refers to a film that as well is exposed to light as to an electric charge, same as in the sensitive drum in a xerox copier.
There are a great number of mechanisms invented that under such circumstances yield a stable image in a consumable film. Some of these may offer reversability.

Such systems typically were devised for high contrast, high exposure photography as in microcopying.

But still, feasable does not necessarily mean photographically or economical benefitial. Photography is much wider field than typically discussed here, with a vast number of processes.

jsmoove · Jul 12, 2017

Are there any systems that offer film rewritability currently? Or if not currently, available to tinker with?

AgX · Jul 12, 2017

Yes, most common as intermediate between classic and digital radiography: Photostimulated Luminescence Film

Such film substitutes the classic consumable radiographic film. After image forming exposure such film is scanned and then erased by light exposure and re-used.

jsmoove · Jul 12, 2017

Photostimulated luminescene, woah thats a new one for me. What im wondering though is - are there similar camera type devices that can write an image to this kind of film, or no? Im curious also about portability/size of the writer. The little blurb I read on the xerocamera mentions that it could be portable. Ill have to read up on radiographic film and photostimulated luminesence.

AgX · Jul 12, 2017

Such films are only sensitive to very short wavelenghts as X-rays and the scanning process is difficult.

But it is still a analog system, more film-like than the xerox drum.

jsmoove · Jul 12, 2017

I found http://calteches.library.caltech.edu/936/1/Xerography.pdf
Which explains in detail how to make a xeroplate, which apparently can be loaded in any camera, not a special camera.

jsmoove · Jul 12, 2017

And in more detail on pg.12: Dead Link Removed

removed account4 · Jul 12, 2017

maybe the article is talking about the xerox copy cameras ?
https://petapixel.com/2015/05/26/el...g-photos-with-the-xerox-photocopying-process/

jsmoove · Jul 12, 2017

Yeah it is. I wonder what kinds of resolutions you can get out of this method. I also wonder if there is a more automated system out there?

Photo Engineer · Jul 12, 2017

Current electrophotography is sometimes bases on a light sensitive Xerographic method used by Kodak and Minolta in their copy machines. Contrary to popular misconceptions this type of film can be made sensitive to R/G/B illumination and is the basis for color copying among other things. One of the films was made from Titanium Dioxide and was repeatedly charged R/G/B to yield full color images in tests I saw at Kodak in the '70s. The Xerographic materials relied on solid plates and UV illumination or other types, but the newer methods used a flexible film with TiO2 or other materials for imaging.

It is really an old method.

Initially, it made only high contrast (Lithographic) images, but modern films supply a continuous tone image measured by a V Log E curve analogous to the D Log E curve where V stands for Voltage.

PE

AgX · Jul 13, 2017

jsmoove said:
And in more detail on pg.12: Dead Link Removed

That article describes the system employed in a Xerox copier. Only that such copier uses a drum, whereas that article has it about a plate, as there the plate is intended for direct viewing, whereas in the copier the image on the drum is only a intermediate in a printing process and only the resulting printed paper is viewed.

(The change from plate to drum is similar to the change from plate to drum in classic printing, with similar advantages.)

Its disadvantage is that the sensitive plate/drum is a hassle in use.
Whereas a film I described above is handled for exposure just like any classic photographic film, but does not yield a directly viewable, stable image...

jsmoove · Jul 13, 2017

@AgX
I see.
I can't seem to find much on photo stimulated luminescence film, are you refering to phosphor plates?

AgX · Jul 13, 2017

See for "Computed Radiography"
That is a means to avoid consumables, keep all images as digital files only, but still use the old radiographic apparatus.
Here these photo stimulated luminescence films are used (sometimes in form of plates).

jsmoove · Jul 13, 2017

Thanks, very interesting. This might be a dumb question, but would there be a way of exposing phosphor film with some sort of camera? Also im reading that the phosphor plate/film is read with a laser scanner...what kind of laser scanner are they referring to? Is phosphor the only type of photo stimulated luminescence?

AgX · Jul 13, 2017

By laser scanning you can trickle the image from the X-ray exposure image to show up.

As sort of camera.... well the radiographic apparatus is sort of camera.
If you refer to visible light and optics, remember that I already stated that such films are not made for image-forming by visible light.

jsmoove · Jul 15, 2017

Do you know what kind of resolution Photostimulated Luminescence Film/plates offer? Right yeah, not visible light obviously. Thanks.

AgX · Jul 15, 2017

Less than silver-haloid film.

Old-N-Feeble · Jul 16, 2017

jsmoove said:
Do you know what kind of resolution Photostimulated Luminescence Film/plates offer? Right yeah, not visible light obviously. Thanks.

I made the mistake of spilling some of that on my lap and turned on the light. ZOWEEE!!

Electrophotographic film question

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