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NEW TOOL: Calculate Relative Brightness (of Wavelengths in nm)


532 with Envy

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Nice little tool.
I was surprised to see 30mW of 532 needed 250mW of 650 for equal brightness.
Thanks for putting this together.:beer:
 

rhd

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No problem :)

I hope people find it useful!
 

mfo

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I'd rep you for this, but I can't because I just did so recently. This is pretty neat.
 

Krogith

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So how accurate is that? Or is it semi generic?

Nice tool thanks for the time it took for you to figure it all out.
 

rhd

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It is as accurate as the CIE tables, which basically have one decimal point of accuracy. IE multiple database entries per each whole number wavelength.

However, apparently some people don't think the CIE tables are perfect enough on their own. So I'm open to input on additional factors to use in weighting.

Also, I'm using the mw as a simple multiplier. This may not be the proper approach.
 

Krogith

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It is as accurate as the CIE tables, which basically have one decimal point of accuracy. IE multiple database entries per each whole number wavelength.

However, apparently some people don't think the CIE tables are perfect enough on their own. So I'm open to input on additional factors to use in weighting.

Also, I'm using the mw as a simple multiplier. This may not be the proper approach.
so like are you saying 100mW is 100X more bright than 1mW? because if so thats not accurate i don't think.
 

rhd

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so like are you saying 100mW is 100X more bright than 1mW? because if so thats not accurate i don't think.
I'm not actually saying that no - but that's how it's in there now.

I thought the common wisdom was 4x power, for 2x visibility increase. However, I need some reliable wisdom on this issue to factor in.

Though - I probably should be a disclaimed up on that tool while in the Alpha stage ;)
 

rhd

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Although, the CIE table does provide a "lumens per watt" value for each wavelength.

This suggests that 100mW will produce 100x the LUMENS of 1mW.

So I suppose an easier to answer question is:
- Do we perceive 2 lumens as twice as bright as 1 lumen?
 

Krogith

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Although, the CIE table does provide a "lumens per watt" value for each wavelength.

This suggests that 100mW will produce 100x the LUMENS of 1mW.

So I suppose an easier to answer question is:
- Do we perceive 2 lumens as twice as bright as 1 lumen?
Yeah but that is starring at the dot, And IMO when I think of beam color I think of the beam it self, and thats where the 4 X's comes into play
 

Leodahsan

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rayleigh scattering or dot-only? :)
very cool, rhd.


hmm, 2.2W 445nm = ~75mW 532nm...
 

Trevor

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You're going to need to throw in the Rayleigh scattering formula. ;)

-Trevor
 

rhd

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Rayleigh Scattering needs to be taken into account.

And if someone could help me figure out where that PHENOMENAL post I read 3 months ago is (the one where the Rayleigh Scattering math was basically stepped through, perhaps for the first time on this forum?), I am anxious to include it in this tool :)
 

Leodahsan

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I've read a lot about that, I saved a txt file here like this (thats for comparing 532nm with other lasers):

factor
660nm > 0.41
650nm > 0.44
635nm > 0.48
532nm > factor 1
405nm > 3.04
445nm > 2.07

You can multiply the equivalent power (lets suppose, 49mW green equals 200mW of 635nm) so with the formula, the equivalent beam for they are:
0.48 for 635nm
49mW . 0.48 = 23.52mW

23.5mW of green will have a beam strength very similar to 200mW 635nm.

Sorry if you can't understand, I found these on a thread I can't remember where...
 

rhd

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That's cool -

I have much more detailed CIE data in there though - so it would be ideal if I could figure out the Rayleigh math to add to the equation, and it would be a pretty darn good comparison tool.

If nobody remembers that thread off hand, I'll re-do the research this weekend, and add it to the tool.

I'm off for the evening.
 




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