Measuring LED lights

john0087

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#1
Hey all,

I have access to a meter that measures light in watts/meters up to 445nm. Technically its a UV meter.

I can measure the following wave lengths:
UVC 250-260nm
UVB 280-320nm
UVA 320-390nm
UVV 395-445

According to the information I have found (Wikipedia) this measurement, watts/meters, is the irradiance of PAR.
Is this measurement useful? I realize that I would be missing a large range for PAR (445-700nm)

I have been searching the web looking for info on coral growth in relation to this measurement, but I couldnt find anything.

Wiki gives a conversion factor to convert this from irradiance to PAR in moles, but it is dependent on wavelength and the calculation is pretty complexha-ha I dont remember my college calc.

Its not waterproof, so all I could do is get surface measurements.

Just wondering if its useful or if anyone could help me convert this info.
I am running 2 AI Hydra 26 about 10 over the water level.

Thanks!

John.
 
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#2
nm refers to the color spectrum.

par is the intensity of the light.

Not the same thing in my limited understanding.
 

john0087

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#3
Right.

So the meter I have access to measures the spectrums up to 445nm. The output is in watts/meters

So the reading would look like this:
UVC – XXX watts/meters
UVB – XXX watts/meters
UVA – XXX watts/meters
UVV – XXX watts/meters

According to Wiki, watts/meters = irradiance of PAR. There are conversion factors to get to PAR, but I could not find any information on them.

Everything that I have found online with regards to reef lighting is all in PAR. I was just asking if the information I could collect is useful or if I could convert it to useful information.

Sorry if I wan't clear in the OP.

John
 
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#4
Right.

So the meter I have access to measures the spectrums up to 445nm. The output is in watts/meters

So the reading would look like this:
UVC – XXX watts/meters
UVB – XXX watts/meters
UVA – XXX watts/meters
UVV – XXX watts/meters

According to Wiki, watts/meters = irradiance of PAR. There are conversion factors to get to PAR, but I could not find any information on them.

Everything that I have found online with regards to reef lighting is all in PAR. I was just asking if the information I could collect is useful or if I could convert it to useful information.

Sorry if I wan't clear in the OP.

John
I have no idea on the conversion. It probably was, I'm not good at math. :)

If you can't put that under the water, I'm not sure it would be useful even if you could convert those readings to PAR.
 
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#6
Yes but you would have to convert the watts/meter squared to microeinsteins which is in umols which is the PAR number we commonly use. Depending on the light source the conversion factor can differ a bit.

http://www.egc.com/useful_info_lighting.php

That is a basic calculator with some common light sources but it does not have the conversion factor for LED. You can measure metal halide and T5 though.
 

john0087

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#7
Yes but you would have to convert the watts/meter squared to microeinsteins which is in umols which is the PAR number we commonly use. Depending on the light source the conversion factor can differ a bit.

http://www.egc.com/useful_info_lighting.php

That is a basic calculator with some common light sources but it does not have the conversion factor for LED. You can measure metal halide and T5 though.

Yeah I read that article as well. I did more research last night and found this article and equation. I think I can handle this math as the explain the inputs pretty well.

https://www.berthold.com/en/bio/how-do-i-convert-irradiance-photon-flux

I am going to take a crack at and see what info I can learn. It will be interesting. We know the PAR meters that are out on the market lack the ability to measure PAR correctly at the UV ranges. While I will be missing measurements between 445nm - 700nm, I am going to have a pretty good understanding of what is going on at the UV range.
 
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