Right Acrylic for a diffuser

[theatrus]

Technically speaking sandblasted glass would diffuse.

I wonder how you would do it without having it diffuse too much.

The Phillips CoralCare fixtures use a blasted glass panel. It’s a pretty soft look.

 

[saltyfilmfolks]

What's odd is that most lights I like prismatic diffuser. A couple I like sanded plexi. None of them I liked the camera diffuser after a couple days of looking at it.

Maybe it’s the different source? Like a Light bulb and and led through the same diff will look different. Naturally.

 

[saltyfilmfolks]

Intensity doesn’t matter, if it cuts it cuts. If you wanted that wavelength, it’s now muted or outright gone.

There is a secondary effect that the method of filtering is absorption, so that energy goes into heating the plastic. However we don’t cook things with UV so it’s not going to matter.

We click things with the other end of the spectrum not uv. And our uv is not really uv.
Intensity does matter as the same wattage led in white has more photons coming out than the same led in “UV”. (Red does this too) because of how they filter the emitter to produce only a single color.
So more difffusion will cut lower photon emitting Leds. Red blue white led have similar output. UV does not. That’s why it’s dim to our eyes. And on a meter.

 

[dantimdad]

Maybe it’s the different source? Like a Light bulb and and led through the same diff will look different. Naturally.

That's my guess

 

[theatrus]

We click things with the other end of the spectrum not uv. And our uv is not really uv.

I'm not sure what you mean by click. However, the bulk of LEDs people talk about in the 440 to 400nm range are violet. If you're using something below this (395, 385) its technically UV-A

Intensity does matter as the same wattage led in white has more photons coming out than the same led in “UV”. (Red does this too) because of how they filter the emitter to produce only a single color.

LEDs do not have filters. They adjust the materials to control the band gap.

> The color of the light (corresponding to the energy of the photons) is determined by the energy required for electrons to cross the band gap of the semiconductor.

Discrete LEDs usually have a spectral half width of 5-10nm.

White LEDs are phosphor conversion devices - they apply a phosphor to a high energy device (usually 445nm royal blues) to convert light to lower energy / longer wavelengths.

So more difffusion will cut lower photon emitting Leds. Red blue white led have similar output. UV does not. That’s why it’s dim to our eyes. And on a meter.

Its dim to our eyes as we just lack the visual ability to see this light. It would be very bright to a mantis shrimp or some insects and birds. I'm not sure what you mean with the rest of your statement, as total radiant energy differs wildly between different LEDs, especially around green and reds. Whites are generally very efficient as we got very good at building AlGaN LEDs in the last twenty years, and the violets are extensions of that band gap material to shorter wavelengths. The violets are lagging for sure in terms of radiant energy, but some of the newer materials are supplanting uses where UV-A fluorescent tubes had been used before (UV curing).

 

[saltyfilmfolks]

That's my guess

Ah.
Pretty much why I went with the sanded. One of my gels cut the intensity the same amount but I liked the way the sanded looked.

 

[dantimdad]

Sorry OP I will move our conversation to a PM.

 

[saltyfilmfolks]

I'm not sure what you mean by click. However, the bulk of LEDs people talk about in the 440 to 400nm range are violet. If you're using something below this (395, 385) its technically UV-A



LEDs do not have filters. They adjust the materials to control the band gap.

> The color of the light (corresponding to the energy of the photons) is determined by the energy required for electrons to cross the band gap of the semiconductor.

Discrete LEDs usually have a spectral half width of 5-10nm.

White LEDs are phosphor conversion devices - they apply a phosphor to a high energy device (usually 445nm royal blues) to convert light to lower energy / longer wavelengths.



Its dim to our eyes as we just lack the visual ability to see this light. It would be very bright to a mantis shrimp or some insects and birds. I'm not sure what you mean with the rest of your statement, as total radiant energy differs wildly between different LEDs, especially around green and reds. Whites are generally very efficient as we got very good at building AlGaN LEDs in the last twenty years, and the violets are extensions of that band gap material to shorter wavelengths. The violets are lagging for sure in terms of radiant energy, but some of the newer materials are supplanting uses where UV-A fluorescent tubes had been used before (UV curing).

Ug. Ok I don’t want to get that deep.so I paraphrased.
But yea, the bottom line here is photons. A uv is throwing less photons. A uv throws less. Doesn’t matter what or who is reviving em.
In the led I have at home it’s the same wattage as the rest and puts out less photons. Not talk g about theories and other leds on the market. Ours our generally matched (for color mixing and power usage) and uv throws the fewest photons.
So adding diffusion cuts the uv more.

 

[saltyfilmfolks]

Sorry OP I will move our conversation to a PM.

It’s all line with the thread really

 

[oreo54]

Ug. Ok I don’t want to get that deep.so I paraphrased.
But yea, the bottom line here is photons. A uv is throwing less photons. A uv throws less. Doesn’t matter what or who is reviving em.
In the led I have at home it’s the same wattage as the rest and puts out less photons. Not talk g about theories and other leds on the market. Ours our generally matched (for color mixing and power usage) and uv throws the fewest photons.
So adding diffusion cuts the uv more.

Well SORT of technically correct.. UV diodes have lower efficiencies than other diodes but that is not a static thing..

..Potential to be 40% efficient versus 4% of current standard UV LEDs (Wall Plug Efficiency)

will depend on the diode and design for the most part but if you want "even photon output normally you would need more UV than say royal blues due
to diode design deficiencies..
https://innovate.osu.edu/available_...-Efficiency-UltraViolet-Light-Emitting-Diodes

Cree royal blue LED delivers 81% wall plug efficiency (UPDATED)

https://www.ledsmagazine.com/articl...lue-led-delivers-81-wall-plug-efficiency.html

Well, diffusion cuts all light a little.. Believe the Coral-life and the Radion filters are both in the 25% range.
That's not "the" issue.
Most common plastics cut off all photons below 400nm to some degree larger than the normal overall 10%
cut..
Charts explain it all
IF you want the cheapest and least absorptive of <400nm then Acrylic -G (plex G) is the best plastic for the job
IF you have wavelengths below say.. 395nm.. for the sake of argument.
You lose some at 400 prob none at 410 w/ any "inferior" plastics..
Decreasing the thickness also increases the transmission level
This is all simple physics

want to avoid all this discussion use float glass and fog it w/ hydrofluoric acid (etching glass, HF acid is quite dangerous btw)

UF-4 is also tolerable.. depending.. as long as diodes aren't "spec'ed" lower than 400
395 peaks at 395 and has half below and half above this...

 

[theatrus]

Well SORT of technically correct.. UV diodes have lower efficiencies than other diodes but that is not a static thing..


will depend on the diode and design for the most part but if you want "even photon output normally you would need more UV than say royal blues due
to diode design deficiencies..
https://innovate.osu.edu/available_...-Efficiency-UltraViolet-Light-Emitting-Diodes

https://www.ledsmagazine.com/articl...lue-led-delivers-81-wall-plug-efficiency.html

Well, diffusion cuts all light a little.. Believe the Coral-life and the Radion filters are both in the 25% range.
That's not "the" issue.
Most common plastics cut off all photons below 400nm to some degree larger than the normal overall 10%
cut..
Charts explain it all
IF you want the cheapest and least absorptive of <400nm then Acrylic -G (plex G) is the best plastic for the job
IF you have wavelengths below say.. 395nm.. for the sake of argument.
You lose some at 400 prob none at 410 w/ any "inferior" plastics..
Decreasing the thickness also increases the transmission level
This is all simple physics

want to avoid all this discussion use float glass and fog it w/ hydrofluoric acid (etching glass, HF acid is quite dangerous btw)

Spot on.

And yeah HF is nasty

 

[adw]

All good info. Please feel free to discuss.

@saltyfilmfolks could you explain the process of using sand paper on the acrylic? What grit do I use and how do I know when I have done it enough?

 

[adw]

Well, diffusion cuts all light a little.. Believe the Coral-life and the Radion filters are both in the 25% range.
That's not "the" issue.
Most common plastics cut off all photons below 400nm to some degree larger than the normal overall 10%
cut..
Charts explain it all
IF you want the cheapest and least absorptive of <400nm then Acrylic -G (plex G) is the best plastic for the job
IF you have wavelengths below say.. 395nm.. for the sake of argument.
You lose some at 400 prob none at 410 w/ any "inferior" plastics..
Decreasing the thickness also increases the transmission level
This is all simple physics

want to avoid all this discussion use float glass and fog it w/ hydrofluoric acid (etching glass, HF acid is quite dangerous btw)

UF-4 is also tolerable.. depending.. as long as diodes aren't "spec'ed" lower than 400
395 peaks at 395 and has half below and half above this...

I guess for my purposes on Radion Gen 3s should I be concerned with losing some or all sub 400 wavelength?

 

[oreo54]

OPP's added wrong link..
corrected:
https://www.amazon.com/gp/product/B07JCGT6VZ/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1
The fact they "shout" CAST at least 1/2 doz times this should work well.
Go to pg 7
https://www.acrylite.net/product/ac...ht-transmission-and-reflectance-tech-data.pdf
no mention of UV "treatment"...
Haven't seen any CAST" to be substantially different than other cast Acrylic (barring treatments)
3 12x12" panels for $30 it's easily doable..

 

[adw]

thanks @oreo5457

Really appreciate everyone's input on this

 

[oreo54]

thanks @oreo5457

Really appreciate everyone's input on this

Thanks for finding the small lot of likely usable stuff.... I always just find huge sheets...

could be thinner.. but now I'm just begging..

 

[saltyfilmfolks]

All good info. Please feel free to discuss.

@saltyfilmfolks could you explain the process of using sand paper on the acrylic? What grit do I use and how do I know when I have done it enough?

400 or 800 grit. Quite simple.

I guess for my purposes on Radion Gen 3s should I be concerned with losing some or all sub 400 wavelength?

No.

 

[saltyfilmfolks]

Well SORT of technically correct.. UV diodes have lower efficiencies than other diodes but that is not a static thing..


will depend on the diode and design for the most part but if you want "even photon output normally you would need more UV than say royal blues due
to diode design deficiencies..
https://innovate.osu.edu/available_...-Efficiency-UltraViolet-Light-Emitting-Diodes

https://www.ledsmagazine.com/articl...lue-led-delivers-81-wall-plug-efficiency.html

Well, diffusion cuts all light a little.. Believe the Coral-life and the Radion filters are both in the 25% range.
That's not "the" issue.
Most common plastics cut off all photons below 400nm to some degree larger than the normal overall 10%
cut..
Charts explain it all
IF you want the cheapest and least absorptive of <400nm then Acrylic -G (plex G) is the best plastic for the job
IF you have wavelengths below say.. 395nm.. for the sake of argument.
You lose some at 400 prob none at 410 w/ any "inferior" plastics..
Decreasing the thickness also increases the transmission level
This is all simple physics

want to avoid all this discussion use float glass and fog it w/ hydrofluoric acid (etching glass, HF acid is quite dangerous btw)

UF-4 is also tolerable.. depending.. as long as diodes aren't "spec'ed" lower than 400
395 peaks at 395 and has half below and half above this...

So, simply put. Anything clear is a good diffuser and impacts light insignificantly for our needs.

Why is complicated.

But it’s just a reef tank.

Find a light diffusion that doesn’t cut light too much and looks nice.

Use a lux or fc meter to make sure it’s not cutting too much.

 

[adw]

How do you know when you have sanded enough? Assuming some sort of uniformity

 

[saltyfilmfolks]

Thanks for finding the small lot of likely usable stuff.... I always just find huge sheets...

could be thinner.. but now I'm just begging..

I have rolls of the stuff.
Used to have the liquid versions too.
(90s was rough with experimenting)