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Ultraviolet Lasers?

tehfrr

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Thank you for all the responses, appreciated.

I already have a 500mw 405nm laser, and it is not suitable, not even close. I definitely want 375nm - 240nm. Nothing lower as 240nm starts generating ozone gas. I want to keep this project relatively sane; Im comfortable with lasers and ultraviolet sources. Poison gas, not so much. Power level - 50mw-500mw. If it needs more than 500mw its time to rethink the whole thing.

The primary application is for reflected ultraviolet photography using a full spectrum converted camera. I have a UV pass filter (Baader U Venus) and the 405nm laser can barely be seen even close up with long exposures. Meanwhile my Convoy C8 flashlight lights things up with a filtered 365nm LED.

My primary uses for a handheld UV laser would be:
-Placing a dot on something a ways off to focus the camera at night. The optics are not made for UV, so there is a focus shift from visible.
-Putting a short but intense burst of UV on plants and non-living objects to induce fluorescence and photograph with a UV cut filter
-Attaching a beam expander and using it similar to an IR laser designator/illuminator
-Rockhounding - looking for fluorescent minerals without needing to be right up on them

Ive successfully done all of these (except for rockhounding) in infrared with a 300mw 808nm laser.

(Edit-grammar)
 
Last edited:



tehfrr

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Here's where I tested the 500mw 405nm laser. I put the beam square on the daisy closest to it:
daisy2.jpg

The full spectrum camera seen in the above picture was maybe 4-5 feet from the flower. Here's the pic it took:
daisy.jpg

Then I turn on my filtered 365nm flashlight and get this:
0665.jpg
 

Alaskan

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Do you really need coherent light from a laser? Short wavelength non-coherent UV LED's are available, but low power. Maybe all you are looking for is an intense UV source? Otherwise you wouldn't have come looking for answers here. Don't welding arcs produce UV too?
 

tehfrr

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yeah UV from an electrical arc is effectively emitted isotropically (like an expanding sphere) so it would take a massive amount of power, Id probably get arc flash burns. Combine that with the fact that UV scatters much easier than visible or IR.. The best I could find was a Wildfire system - UV light made for the entertainment industry. Still not enough throw, and also would cover a large area indiscriminately.
 

tehfrr

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Example, all 3 shots from the same place. Mt Adams as seen from Mt Rainier (WA)

Visible:
DSC_0532.jpg

Infrared:
DSC_0531.jpg

Ultraviolet:
DSC_0530.jpg
 

Alaskan

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I guess you want to stick with 365 -375 nm, instead of getting a different filter.
 

tehfrr

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well, Id go lower, but as far as going higher, it would defeat the entire point to use visible (or near visible) light.
I tried using my 500mw 405nm laser, no good
 

kecked

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A nitrogen laser sounds ideal provided it has acceptable divergence. It’s pulsed and easy to build. Has high peak power so it should be bright at a great distance provided the beam stays together. A telescope beam expander likely could help but you’ll need really good and hence expensive optics. The next option is a pulsed dpss 355nm laser. I’m not sure the pass and of your filter. Interesting application. What does it tell you that normal photography does not? I’ve seen it for showing skin damage from sun exposure.

at those distances, if you can place a bright uv led, it should appear as a point source for focusing.

if you can go a little less portable, a HeCd would also work.
 

icecruncher

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Thank you.

I knew there was a reason :)

It is possible to activate both the short-persistence zinc sulfide materials as well as the long-persistence strontium aluminate materials using a standard blu-ray diode at 405 nm. However, this results in a visible spot of bright light on the surface when you are drawing. (The spot appears sort of blueish-white and is a mix of reflected 405 and the green fluorescence from the paint.)

If you had a truly invisible UV beam then you would not see this bright spot. Instead, the only color you would see would be the ghostly green fluorescence as the image was drawn. This is likely the reason that DK is searching for a UV diode for his glow-in-the-dark builds.

Adam
 

hakzaw1

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His GITD projectors are INCREDIBLE. It was a treat seeing one in person at least year's SELEM.
damn
another reason I am unhappy missing a few SELEMs after making 5 in a row.
Drake has been a great friend--helped me once a long time ago...I would like to know what lasers etc he brought to SELEM from Wisconsin. He needs to host a LEM there.. I would be there.
about UV and GITD.
They go great together.. the time & look that the GITD glows can be varied by laser power, the wavelength and how well the GITD screen holds the image..I am working on some scrims that are GITD coated- and what passes thru these hits another GITD screen--kinda a 3D look.

hak
 

WizardG

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damn
another reason I am unhappy missing a few SELEMs after making 5 in a row.
Drake has been a great friend--helped me once a long time ago...I would like to know what lasers etc he brought to SELEM from Wisconsin. He needs to host a LEM there.. I would be there.
about UV and GITD.
They go great together.. the time & look that the GITD glows can be varied by laser power, the wavelength and how well the GITD screen holds the image..I am working on some scrims that are GITD coated- and what passes thru these hits another GITD screen--kinda a 3D look.

hak
I've tried a few things along these lines using different colors of laser to excite different phosphors on the same scrim. I coated a sheet with a mixture of red, green and blue phosphors (from readysetglo). A green laser would excite only the red phosphor. Blue laser would excite the green phosphor strongly and the red weakly. A 405 laser was required to excite the blue phosphor and it lit the green up too but had little effect on the red. Fun stuph except for the smell. The red phosphor smells like rotten eggs so all experiments had to be done outdoors. That sheet will clear a room in a few minutes.
 

Buffo

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Drake has been a great friend--helped me once a long time ago...I would like to know what lasers etc he brought to SELEM

He had a few lasers with him, but honestly I think he was so overwhelmed by everything else that he didn't really have time to do anything with the stuff he brought. I remember that he had plans to assemble something during the event, but he got so distracted that he actually ended up leaving some of the parts behind in the cafeteria! (We mailed them back to him of course.) He ended up setting up near Aron Bacs in the cafeteria, so I know he got a good look at Aron's amazing home-brew abstract software. I also saw him in the ion laser work room more than a few times chatting with David Francis and Wil Carter while gawking at all the lovely mixed gas units running in there. (In fairness, we were all gawking though; we had more ions last year than ever.)

I am working on some scrims that are GITD coated- and what passes thru these hits another GITD screen--kinda a 3D look.

Is this long-persistence or short? And how do you apply the GID paint to the scrim without clogging the holes?

I thought about painting some "skeeta-scrim" material with zinc-sulfide, but after talking with DK I shelved the idea because he was saying that the paint is pretty thick (consistency) and I was worried that I'd just end up making a sheet...

I've tried a few things along these lines using different colors of laser to excite different phosphors on the same scrim. I coated a sheet with a mixture of red, green and blue phosphors (from readysetglo). A green laser would excite only the red phosphor. Blue laser would excite the green phosphor strongly and the red weakly. A 405 laser was required to excite the blue phosphor and it lit the green up too but had little effect on the red. Fun stuph except for the smell. The red phosphor smells like rotten eggs so all experiments had to be done outdoors. That sheet will clear a room in a few minutes.

Fascinating! Do you have pictures of the result? What is the duration (persistence) of the phosphors? I can see this being used with some of the more complex circular raster abstract effects to re-create those infamous psychedelic album covers that were so popular in the 1960's. :)

Regarding the smell of the phosphor, does the smell persist even weeks after it's been applied and dried? If so, I wonder if you could seal it in place with a top-coat of clear material.?. Thinking that maybe you could thin out some satin-finish polyurethane varnish and then spray it over the scrim? Although Acrylic Urethane (basically automotive clear-coat) might be even better since it's usually water based. So long as the sealer doesn't dissolve or wash away the phosphor it should hold in the stink while having a minimal effect on the color.

I'm assuming you purchased the phosphor in powdered form and then mixed it with a solvent before you applied it, right? Or did it come pre-mixed? Either way, what is the solvent? Did you have to spray it on? And did you have to apply a fixing agent?

Sorry for all the questions, but this is a really interesting idea. DK and I spoke about the idea of adding extra colors to his GID display about a year ago, but that was limited to just painting different sections of the wall with different colors, which isn't really all that useful, so we decided it was a non-starter. But having all 3 primary colors available anywhere on the display surface, with a long-enough persistence to allow the scanners to draw very complex shapes, would allow for TV-quality images to be created. That is something worth trying!

In closing, for anyone who has not yet seen the amazing glow-in-the-dark laser artwork that DK has done, here is a link to my all-time favorite piece that he put together. The music just screams "Disney" to me, which certainly fits with the whimsical nature of the artwork. The video does not do justice to this effect, but you can get some idea of how cool it is. (The "reveal" at the end is *much* more dramatic in real life - mostly because of the sudden change in brightness, which the camera doesn't convey very well.)

For a sense of scale: the image is being drawn on a wall that is ~ 8 ft tall and 10 ft wide. (Full link: )

Adam
 

steve001

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The red phosyphor smells like rotten eggs so all experiments had to be done outdoors. Fun stuph except for the smell. That sheet will clear a room in a few minutes.
Blame it on the red phosphore. Yeah right
 

WizardG

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He had a few lasers with him, but honestly I think he was so overwhelmed by everything else that he didn't really have time to do anything with the stuff he brought. I remember that he had plans to assemble something during the event, but he got so distracted that he actually ended up leaving some of the parts behind in the cafeteria! (We mailed them back to him of course.) He ended up setting up near Aron Bacs in the cafeteria, so I know he got a good look at Aron's amazing home-brew abstract software. I also saw him in the ion laser work room more than a few times chatting with David Francis and Wil Carter while gawking at all the lovely mixed gas units running in there. (In fairness, we were all gawking though; we had more ions last year than ever.)



Is this long-persistence or short? And how do you apply the GID paint to the scrim without clogging the holes?

I thought about painting some "skeeta-scrim" material with zinc-sulfide, but after talking with DK I shelved the idea because he was saying that the paint is pretty thick (consistency) and I was worried that I'd just end up making a sheet...



Fascinating! Do you have pictures of the result? Sadly, no. Many pictures were taken but not by me :-( (see below) What is the duration (persistence) of the phosphors? See below I can see this being used with some of the more complex circular raster abstract effects to re-create those infamous psychedelic album covers that were so popular in the 1960's. :)

Regarding the smell of the phosphor, does the smell persist even weeks after it's been applied and dried? It lasts until ambient moisture has destroyed all the red phosphor. I really needed to spray a couple coats of sealer on the thing. If so, I wonder if you could seal it in place with a top-coat of clear material.?. Ding! Thinking that maybe you could thin out some satin-finish polyurethane varnish and then spray it over the scrim? Although Acrylic Urethane (basically automotive clear-coat) might be even better since it's usually water based. So long as the sealer doesn't dissolve or wash away the phosphor it should hold in the stink while having a minimal effect on the color. The red phosphor is ruined by contact with water so I used a solvent based acrylic carrier. I should have sprayed on a couple of coats of sealer. The smell was from the phosphor reacting with moisture in the air. The reaction ruins the phosphor and releases hydrogen sulfide and, from the way it smelled, possibly some hydrogen selenide or some other selenium compound. (Selenium anything generally smells pretty bad.)

I'm assuming you purchased the phosphor in powdered form and then mixed it with a solvent before you applied it, right? Or did it come pre-mixed? Either way, what is the solvent? Did you have to spray it on? And did you have to apply a fixing agent? The powders are really friggin dense. The acrylic I was using was way too thin to suspend the powders for more than a minute ot two. I wound up using a brush and stirring and painting like a manic having a seizure to get the stuff as evenly distributed as I could. I wanna try this again, but I'll do a few things quite differently :)

Sorry for all the questions, but this is a really interesting idea. DK and I spoke about the idea of adding extra colors to his GID display about a year ago, but that was limited to just painting different sections of the wall with different colors, which isn't really all that useful, so we decided it was a non-starter. But having all 3 primary colors available anywhere on the display surface, with a long-enough persistence to allow the scanners to draw very complex shapes, would allow for TV-quality images to be created. That is something worth trying! Well, I was thinking along the same lines but there are a few hitches. The phosphors have very different persistence times, Red-a few minutes, Green, an hour or so. Blue, about half that. Also, I couldn't make red, green and blue light up individually. Red I could light up by itself but the blue laser would give me a bright green trace with the red fading quickly so yellow fading to green. And the 405 would light up the blue and green phosphors but not do much for the red. I wound up hanginng the sheet up at a festival @ night. I had my lasers and a photoflash ans a few LED light pens of different colors for people to play with. A good time was had by many!

In closing, for anyone who has not yet seen the amazing glow-in-the-dark laser artwork that DK has done, here is a link to my all-time favorite piece that he put together. The music just screams "Disney" to me, which certainly fits with the whimsical nature of the artwork. The video does not do justice to this effect, but you can get some idea of how cool it is. (The "reveal" at the end is *much* more dramatic in real life - mostly because of the sudden change in brightness, which the camera doesn't convey very well.)

For a sense of scale: the image is being drawn on a wall that is ~ 8 ft tall and 10 ft wide. (Full link: )

Adam
 

kecked

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Not sure if this would work but you might put a water repellant spray over it instead of a polymer spray coat. That will keep the water out and let it breath. There is a risk with an over spray that you might quench the phosphorescent emission. The repellent should not so that and will keep water vapor out.
 

Buffo

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The phosphors have very different persistence times, Red-a few minutes, Green, an hour or so. Blue, about half that. Also, I couldn't make red, green and blue light up individually. Red I could light up by itself but the blue laser would give me a bright green trace with the red fading quickly so yellow fading to green. And the 405 would light up the blue and green phosphors but not do much for the red.

Thanks for the extra info. OK, so there goes my idea for an RGB Phosphor coated TV wall. :rolleyes:

The H2S and H2Se sound pretty nasty! Hopefully next time a top coat of acrylic will seal out the water and prevent that.

Adam
 




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