Lens material

[Elevator Dude]

Hi, I hope everyone is having a great weekend. I am interested in adding a lens to my strip build to protect the diodes and I wanted to know the pros and cons of different materials. I was planning on using a square sheet of acrylic attached to the frame roughly 1/2 an inch below the diodes but am open to other options.

[TEKNIK]

Poly carb is usually better due to transparency also flexibility. Acrylic can break pretty easy if it's thin.
It's often better to leave a very small gap between the LEDs and the cover, light will bounce between the cover and the pcb so you increase the output by making the distance the light bounces shorter.
If you are using strips then light will reflect off the cover and bounce between the strips before it is reflected back to go through the cover.
You can buy heatsinks with protective covers and they are usually the best solution for a strip build.

[Elevator Dude]

Thanks for the reply, I wish I had known about the heatsinks with lens holders built in when I put this light together. I was thinking if I keep the lens off the pcb a bit it would be better for airflow and cooling I hadn't considered the reflection aspect.

Off to look for sheets of poly carb, the plan is to use one sheet to cover a 34x46 frame x2.

[TEKNIK]

If you have a lux meter please measure before and after as it will help people understand the difference

[Ambient]

If you have a lux meter please measure before and after as it will help people understand the difference

MIGRO did a split-test for an HLG board using acrylic vs no-acrylic and the results were around a 1.4% reduction in output.

Here's the video:



I'm reading that acrylic and plexi both block UV light. Does anyone know this to be true?

[TEKNIK]

Both materials can block uv light. There are alot of variations to the and some will block more than others.

While I think migrow is a pretty cool guy, he does not have the right equipment to come to that conclusion. 1.4% is not realistic from a cheap cover. It will be 96% at best.

[YYCannabis]

@TEKNIK Do you have a link to those heatsinks with covers?

For plastics...most plastics are designed to block UV so the material doesn’t deteriorate from sunshine. When shopping for any type of clear plastic/polycarbonate be sure that it is NOT specific to blocking UV.

For my work, we needed clear (no UV or IR coatings) glass that was 1.5mm thick and cut to very small dimensions of approx 5mm x 20mm. No glass shop carried anything like that or would not cut such small pieces. We eventually located an art school that taught how to make stain-glass windows. They had the right glass, and the skills to make hundreds of these small pieces for us.

Just some food for thought about the lenses. I think I would rather do glass than plastic.

Cheers
YYC

[Capt. Saicin]

I bought opal/opaque acrylic/PMMA sheets, 3mm for my LM301B strips and they do really well.
Datasheet says something like 92% transmission...it's diffusing the light really well.
Hard shadows are gone, seems to be more uniformly lit throughout the plant but that's just eyeballing it.
Pictures taken with half wattage. Burned plant matter was from before i added the cover.

The tomatos are a bit unruly and they extend well over the lights up to the ceiling by now

[Ambient]

Both materials can block uv light. There are alot of variations to the and some will block more than others.

While I think migrow is a pretty cool guy, he does not have the right equipment to come to that conclusion. 1.4% is not realistic from a cheap cover. It will be 96% at best.

The 1.4% seems too good to be true. All acrylic that I've seen that's reasonably priced is stated @ 88-92% of light transmission.

I'm wondering what sizes these were tested w/ by the company. I plan on going w/ 1/16" acrylic. Maybe that's why he got those readings? Maybe the standards are done using the most common sizes people purchase. Dunno.

@TEKNIK Do you have a link to those heatsinks with covers?

For plastics...most plastics are designed to block UV so the material doesn’t deteriorate from sunshine. When shopping for any type of clear plastic/polycarbonate be sure that it is NOT specific to blocking UV.

For my work, we needed clear (no UV or IR coatings) glass that was 1.5mm thick and cut to very small dimensions of approx 5mm x 20mm. No glass shop carried anything like that or would not cut such small pieces. We eventually located an art school that taught how to make stain-glass windows. They had the right glass, and the skills to make hundreds of these small pieces for us.

Just some food for thought about the lenses. I think I would rather do glass than plastic.

Cheers
YYC

I would love to go w/ glass, but I need to thermoform the acrylic to fit my setup.

From what I'm reading, all acrylic/plexi/polycarb blocks UVC & UVB. Some UVA is let in.

They sell UV transmitting acrylic online in sheets that are typically used for sanitation stuff and tanning beds, but these run pretty high per sheet. All I need is a 8" x 48" sheet of 1/16".

Sucks that UV is blocked to a certain extent as this increases/decreases the potential of certain crucial marijuana elements (like THC & CBD): https://www.blackdogled.com/blogwhich-i ... va-or-uvb/

I bought opal/opaque acrylic/PMMA sheets, 3mm for my LM301B strips and they do really well.
Datasheet says something like 92% transmission...it's diffusing the light really well.
Hard shadows are gone, seems to be more uniformly lit throughout the plant but that's just eyeballing it.
Pictures taken with half wattage. Burned plant matter was from before i added the cover.

The tomatos are a bit unruly and they extend well over the lights up to the ceiling by now

As long as it's working, but I don't see how opaque panels transmit 92% of light. The few I see are rated @ 45-69% of LT. That's from TAPPLASTICS. Clear panels w/ no extra additives are 88-92% of LT. This is only because of building standards they have to meet which stipulates that they need to block UV to a certain extent.

[TEKNIK]

I test these things a fair bit and 92% is common. It's usually the German plastic from Bayer, I think it was Mitsubishi that has a few good ones too. Glass is the best, I know there is particular types of glass available that transmit 96% then there is a special anti reflective coating they add to the glass and it gets to 98%. Distance from where the leds are positioned to the cover also makes a big difference. As the light that doesn't transmit is mostly reflected the closer the LED's to the cover the more transmission will occur. The other good thing about glass is you can clean it properly, plastics scratch easy. That black dog company sure knows how to charge for a light.