Phosphorus idea my mechanical sstv origins

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Phosphorus idea my mechanical sstv origins

Postby Harry Dalek » Sat Aug 15, 2009 5:17 pm

Hi all did some experiments with patricks idea Phosphorus wall stickers..
Well i tried a while back with a laser and didn't seem to get an effect tried today with a focused Led ..i know now the laser is red light and the led is white a mix of light colours and the Phosphorus wall sticker is green so i think it likes green light to work ..so perhaps a green laser would of worked better ...Any case heres a video ..still trying to get my head around if its worth making a screen ...seems similar to a scope Phosphor for its lag time.


Glow-in-the-dark toys

Spectra of constituent blue, green and red phosphors in a common cathode ray tube.
Calcium sulfide with strontium sulfide with bismuth as activator, (Ca,Sr)S:Bi, yields blue light with glow times up to 12 hours, red and orange are modifications of the zinc sulfide formula. Red color can be obtained from strontium sulfide.
Zinc sulfide with about 5 ppm of a copper activator is the most common phosphor for the glow-in-the-dark toys and items. It is also called GS phosphor.
Mix of zinc sulfide and cadmium sulfide emit color depending on their ratio; increasing of the CdS content shifts the output color towards longer wavelengths; its persistence ranges between 1–10 hours.
Strontium aluminate activated by europium, SrAl2O4:Eu(II):Dy(III), is a newer material with higher brightness and significantly longer glow persistence; it produces green and aqua hues, where green gives the highest brightness and aqua the longest glow time. SrAl2O4:Eu:Dy is about 10 times brighter, 10 times longer glowing, and 10 times more expensive than ZnS:Cu. The excitation wavelengths for strontium aluminate range from 200 to 450 nm. The wavelength for its green formulation is 520 nm, its blue-green version emits at 505 nm, and the blue one emits at 490 nm. Colors with longer wavelengths can be obtained from the strontium aluminate as well, though for the price of some loss of brightness.

In these applications, the phosphor is directly added to the plastic from which the toys are molded, or mixed with a binder for use as paints.

ZnS:Cu phosphor is used in glow-in-the-dark cosmetic creams frequently used for Halloween make-ups. Generally, the persistence of the phosphor increases as the wavelength increases. See also lightstick for chemiluminescence-based glowing items.
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Postby dominicbeesley » Mon Aug 17, 2009 10:12 pm

Hi Harry,

looks promising. Have you tried blue or even better ultra-violet LEDs many phosphoresent things are worked by ultra-violet light and this would give the possibility (with suitable filtering to protect people's eyes) of an "invisible" scanning beam

Dom
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Postby Marcus » Tue Aug 18, 2009 11:07 pm

Thats pretty cool,
I remember I got some chalk given to me that was phosphorescent...
A quick ebay-ing turned this up that might be interesting to paint a surface with?
http://cgi.ebay.com.au/Glow-In-the-dark ... tsupported
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Postby Harry Dalek » Wed Aug 19, 2009 11:25 pm

dominicbeesley wrote:Hi Harry,

looks promising. Have you tried blue or even better ultra-violet LEDs many phosphoresent things are worked by ultra-violet light and this would give the possibility (with suitable filtering to protect people's eyes) of an "invisible" scanning beam

Dom


MMM interesting no have not tried that !
I think Patricks thinking outside the box is a pretty good idea it seems to work using your Leds might make this idea useful..
What i could see was it was the same as looking at a scope screen...but its lag might just cause ghosting...
Your leds might be the thing for this ?
Harry
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Postby Harry Dalek » Wed Aug 19, 2009 11:31 pm

Marcus wrote:Thats pretty cool,
I remember I got some chalk given to me that was phosphorescent...
A quick ebay-ing turned this up that might be interesting to paint a surface with?
http://cgi.ebay.com.au/Glow-In-the-dark ... tsupported


Yes i will have a look...
to make one you would need something like paint to do it right .
Using UV leds is another pretty good idea and for this i can see another new tv system being invented .
Little did patrick know ? well it was hes idea :lol: :lol:
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Postby Klaas Robers » Mon Aug 24, 2009 6:02 am

UV-LEDs are not that easy to get. But for phosporisation blue LEDs are just as suitable. The screen then may phosphorise green. Then use a pair of spectacles with yellow glass in it and you wouldn't see the blue scanning spot. This is the same as the old P7 picture tubes that we used for SSTV. A bright blue scanning spot and a green afterglow of the screen.
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Postby Harry Dalek » Fri Aug 28, 2009 12:31 am

Klaas Robers wrote:UV-LEDs are not that easy to get. But for phosporisation blue LEDs are just as suitable. The screen then may phosphorise green. Then use a pair of spectacles with yellow glass in it and you wouldn't see the blue scanning spot. This is the same as the old P7 picture tubes that we used for SSTV. A bright blue scanning spot and a green afterglow of the screen.


I still am wondering if it would have any use for us i can see SSTV yes could make a nipkow Slowscan tv with a screen like this ..what else perhaps doing the same for a fast crt and putting that in front turning it into a p7 ,i havn't tried to see if a low light led would be better with this in front if so then it would be good.
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Postby dominicbeesley » Fri Aug 28, 2009 12:52 am

I think it might be worthwhile for demonstration machines to reduce flicker. Some people I've shown the setup to find it very difficult to "find" the picture at first as it is so flickery they just can't make anything out.

Once they've "got it" they then can see the picture quite well.

It would be brilliant if we could find/develop a diffuser made of phosphorscent material to go in front of a nipkow which could then be switched for a normal one....

I'm tempted to replace the LED in my MUTR kit with a blue/UV one to test the theory. I've not got any phosphorscent material though...

Dom
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Postby Klaas Robers » Fri Aug 28, 2009 6:20 am

The problem too is that the afterglow of the P7 picturetubes is fat too slow. SSTV gives one picture each 7,2 sec. and the afterglow is more or less suited to that. For NBTV this slow a screen will show a lot of smear in the moving objects. The advantage of NBTV over SSTV is that it shows moving pictures where SSTV is more a series of stills.
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Re: Phosphorus idea my mechanical sstv origins

Postby johnrpm » Wed Jul 05, 2017 9:17 am

flourocein (not sure of the spelling) is used to attenuate lasers, the light penetrates according to brightness, this could be used to give 3d effect if viewed at an angle, maybe a depthmap projection into sealed tank, imagine a face with the nose brightest .
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Re: Phosphorus idea my mechanical sstv origins

Postby Harry Dalek » Wed Jul 05, 2017 10:13 am

johnrpm wrote:flourocein (not sure of the spelling) is used to attenuate lasers, the light penetrates according to brightness, this could be used to give 3d effect if viewed at an angle, maybe a depthmap projection into sealed tank, imagine a face with the nose brightest .


Hi John long time no see ~! Thats interesting i suppose the camera part is the problem perhaps the same laser idea and a flying spot pickup a bit like Alberts 360 degree camera he was planning or almost might work.

I was also thinking a while back about heat sensitive paint for a sstv but the laser needed i think is not worth the cost glow paint and any old uv laser is a lot cheaper and easier .
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Re: Phosphorus idea my mechanical sstv origins

Postby johnrpm » Wed Jul 05, 2017 10:38 am

Hello Harry,
I might make a thin box to hold the flourocein and put it in front of my televisor just to see what happens.the stuff I have is powder, and added to water, they use it to find leaks, trace water courses and eye surgery, so its safe to use, it fluoresces when lit with white light but better with uv. I spent some time building a cnc painting machine, and now building an orrery, played around with tesla coils and high voltage stuff, to many interesting things to make but never enough time.

all the best
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Re: Phosphorus idea my mechanical sstv origins

Postby Harry Dalek » Wed Jul 05, 2017 3:29 pm

johnrpm wrote:Hello Harry,
I might make a thin box to hold the flourocein and put it in front of my televisor just to see what happens.the stuff I have is powder, and added to water, they use it to find leaks, trace water courses and eye surgery, so its safe to use, it fluoresces when lit with white light but better with uv. I spent some time building a cnc painting machine, and now building an orrery, played around with tesla coils and high voltage stuff, to many interesting things to make but never enough time.

all the best
john


So its either a powder or liquid ..powder i found was a bit grainy for pictures as a liquid you could mix it with paint or dip paper in for screen ,i tried a glow paint screen with a uv laser wasn't to bad but not really needed for NBTV it made it no brighter i want the afterglow for SSTV your chemical i have no idea what results it might show so post up the results
Funny we are talking about this your help with the polygon laser scanner mirror drivers a few years ago got that working and i in one test tried the glow screen.
Do post up again before 2020 ! :wink:
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Re: Phosphorus idea my mechanical sstv origins

Postby johnrpm » Wed Jul 05, 2017 10:56 pm

I suppose the afterglow time must match the scan speed, the flourocein is pretty fast, this may be interesting.

https://hackaday.com/2011/01/18/phospho ... -painting/
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Re: Phosphorus idea my mechanical sstv origins

Postby Harry Dalek » Thu Jul 06, 2017 9:54 am

johnrpm wrote:I suppose the afterglow time must match the scan speed, the flourocein is pretty fast, this may be interesting.

https://hackaday.com/2011/01/18/phospho ... -painting/



What i found you reduce the laser level a touch but the after glow is not good when its over written so fast it was a bit point less for NBTV best have none for a NBTV monitor ,when i was doing research on all this i recall it was mentioned a red laser acted as a rubber stopping the after glow i tried it but didn't notice that effect might be that laser level needed but i didn't really need it as by the time my glow drum rotated again for the next picture it was faded enough for a new scan on the mechanical SSTV monitor .
Another effect of this type of way to write an image on a glow screen is if you kept looking at that picture of that man on the link you would see after a short time the image start to defocus the glow would be there for ages but image fades away .
Very useful for SSTV or even perhaps Fax i am pretty sure you could double the scan time it would out do a p7 CRT .
Do experiment with it its very interesting .i still have my DC motor mini version of the monitor to finish but always getting side tracked on other stuff /
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