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# 2W MCU-C88 Q5 26650 Host

#### qumefox

##### New member
in that case, this would be totally incorrect?
Beam: (445nm 1000mw) vs. (445nm 4000mw)
(maybe thats why all the 1W 445's on YouTube is brighter than 200mw greens :/)
Actually I think you just discovered a rather serious flaw in RHD's calculator.. It doesn't take into consideration that brightness changes across powers aren't linear.

FOund this thread on PL on the subject. It doesn't have the data in it, but it does say who to ask about it.

http://www.photonlexicon.com/forums...-some-helping-explaining-power-vs.-brightness

I also notice that that calculator doesn't agree with chroma on equivalent brightnesses. RHD's calculator says 1W of 532nm is equal to just under 30W of 445, where as chroma shows it as 20W of 445 as having the equivalent brightness.

So I think there is some math missing somewhere.

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#### blue bumblebee

##### New member
hmm, it took me a while to figure out what was wrong
because i thought my "200mw green" was brighter than a 1W blue
but on youtube, the 1W blues always drown out the green

#### qumefox

##### New member
The only real world examples I have handy is the beam on a 45mW 532 looks 'about' the same brightness wise as a 375mW 445. Which rhd's calculator doesn't agree with either. It says the 445 should be about 60% the brightness of the 432.

So like I said, it kind of looks like there is some math either missing, or messed up, somewhere.

And also, it makes sense that high power 445's will drown out low power greens to a camera.. Camera's aren't eyeballs. They see things differently..

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#### Kevlar

##### New member
Hey qumefox, do you remember this thread? http://laserpointerforums.com/f44/200mw-red-equivalent-how-much-green-53813.html#post758774 ?

I always refer back to it when these type of questions come up. It seems to me the best method on figuring out what strength wavelength compares in brightness to a different wavelenth's strength.

"200mw 635nm red = 23.827mw green
200mw 650nm red = 10.680mw green
200mw 660nm red = 5.721mw green
1W 445nm = 99.270mw green
600mw 405nm = 9.6077mw green
Using chroma and taking Rayleigh scattering into account"

#### qumefox

##### New member
I remember that thread, but can never find it when I look for it heh.

Using the ratios posted there, I get 375mW of 445 being equal to 38mW of 532.. which is fairly close to agreeing with my statement that my 45mw 532 looks about as bright as my 375-400mW 445.

So yeah. I think RHD's math got messed up somewhere.

#### rhd

##### New member
I also notice that that calculator doesn't agree with chroma on equivalent brightnesses. RHD's calculator says 1W of 532nm is equal to just under 30W of 445, where as chroma shows it as 20W of 445 as having the equivalent brightness.

So I think there is some math missing somewhere.
Actually, Chroma doesn't account for Raleigh scattering.

Hey qumefox, do you remember this thread? http://laserpointerforums.com/f44/200mw-red-equivalent-how-much-green-53813.html#post758774 ?

I always refer back to it when these type of questions come up. It seems to me the best method on figuring out what strength wavelength compares in brightness to a different wavelenth's strength.

"200mw 635nm red = 23.827mw green
200mw 650nm red = 10.680mw green
200mw 660nm red = 5.721mw green
1W 445nm = 99.270mw green
600mw 405nm = 9.6077mw green
Using chroma and taking Rayleigh scattering into account"
Beam: (635nm 200mw) vs. (532nm 23.82mw)
Beam: (650nm 200mw) vs. (532nm 10.68mw)

- Looks dead on to me. You can plug in the rest of the values, they should all work. So where's the flaw?

#### qumefox

##### New member
I know chroma doesn't account for Rayleigh scattering... My above statement was after using the correction factors posted in the original thread (which I was involved in, so please don't lecture me on Rayleigh scattering heh) and doing the math manually.

However.. Your calculator's numbers for the 'dot' don't match Chroma either... Which has proven to be relatively 'close' to the real world.

Something is just messed up somewhere in your math is all i'm saying. If the numbers for the 'dot' aren't right, then neither are the ones accounting for Rayleigh scattering. (which will be based on the numbers for the dot with a correction factor applied.)

I'm just saying this. Real world, my 40-45mW 532nm looks 'about' as bright as my 375mW 445nm.. I should know.. I was playing with them both again last night before bed..

Letting chroma do the math for the dot comparing 445 to 532, then applying the final correction factor seoguy posted in the initial thread yields a result of about 37mW of 532nm being equal to 375mW of 445nm. According to Chroma, 375mW of 445 is equal to 17.966mW of 532, so 18mW for simplicities sake.. Since the 445 is the 'fixed' power we want to know the 532 equivalent to, that means the green side is the one that needs the correction factor applied.. so 18mW x 2.043 = 36.774mW of green being equivalent to 375mW of 445.

Your calculator comparing 375mW of 445nm, compared to ? mW of 532nm and set on beam fills in the blank as 26.17mW of 532nm being equal to 375mW of 445... Which I can tell you is nowhere near right after the real world test.

So like I said.. Something is messed up somewhere in your math. You can get mad at me all you want, but it's still true.

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#### rhd

##### New member
I always refer back to it when these type of questions come up. It seems to me the best method on figuring out what strength wavelength compares in brightness to a different wavelenth's strength.

"200mw 635nm red = 23.827mw green
200mw 650nm red = 10.680mw green
200mw 660nm red = 5.721mw green
1W 445nm = 99.270mw green
600mw 405nm = 9.6077mw green
Using chroma and taking Rayleigh scattering into account"
OK - so these are the accepted accurate numbers?

Beam: (635nm 200mw) vs. (532nm 23.82mw)
Beam: (650nm 200mw) vs. (532nm 10.68mw)

- Looks dead on to me. You can plug in the rest of the values, they should all work. So where's the flaw?
And those are the values that the calculator generated.

Something is just messed up somewhere in your math is all i'm saying. If the numbers for the 'dot' aren't right, then neither are the ones accounting for Rayleigh scattering. (which will be based on the numbers for the dot with a correction factor applied.)

Your calculator comparing 375mW of 445nm, compared to ? mW of 532nm and set on beam fills in the blank as 26.17mW of 532nm being equal to 375mW of 445... Which I can tell you is nowhere near right..

So like I said.. Something is messed up somewhere in your math. You can get mad at me all you want, but it's still true.
It looks to me like the calculator is producing exactly the same values as Chroma with the factors accounted for manually. IE (as Kevlar said):
"200mw 635nm red = 23.827mw green"
Beam: (635nm 200mw) vs. (532nm 23.82mw)

So again - looks like it's getting it bang on. If the blue values aren't equating to Chroma's with Raleigh factoring, that's not surprising. There's some debate about the accurate values for blue. But remember, my calculator doesn't "calculate" that part of the function - it references it from CIE tables. There are different CIE tables, and from my understanding, the primary difference is the blue range.

I *think* Chroma uses the CIE 1931 or 1975 tables.
I *think* my calculator uses CIE 1978 tables.

(I don't remember with 100% confidence from memory - but that's my best recollection)

I don't particularly know the tables I'm using to be better than Chroma, they were simply the most recent set of data I was able to access when I made the tool. The only difference, if there is any difference, should be in blue range.

That said, if people are dead set on this calculator matching Chroma, it would be trivial for me to swap the datasets and use the CIE 1931 tables that Chroma uses. In fact, I think I actually have both tables already in the database, and it would just be a "flip of a switch".

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#### qumefox

##### New member
How about you try it with 445 hmm? Since that was what I was dealing with AND talking about?

I'm not sure why you keep referencing 650nm when i'm talking about blues.

And while your at it, actually compare a 375mW 445 with a 26mW 532nm (your calculator) and a 37mW 532nm (chroma's output + seoguy's correction factors) then get back to me on which is closer to being right... I have no way of knowing if chroma + the mentioned correction factors is anywhere near exact. All I know is that it's pretty damn close. I'll try to go through all my green modules and pens and see if I can find one that's around 26mW to compare.. Though I expect it to appear much dimmer.

But it boils down to.. you can either check out and verify my results, which don't agree with your calculator.. Or just ignore me and go on with life. Doesn't matter to me. I can continue to use chroma + seoguy's math just like I have been since we had the original discussion since I know it's 'about right'.

It's up to you if you want to fix your calculator or not..

You should also keep in mind that brightness isn't linear. When comparing the same wavelength, 2W of anything won't be 'twice as bright' as 1W of the same wavelength. This will actually also affect comparing other wavelengths as well to varying extents depending on the powers involved.

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#### rhd

##### New member
Since you love your Chroma values here, if you'd like to use the older tables used in Chroma, add the following URL argument to the link and it will fall back to the those tables instead. At the end of the URL to the calculator, add "?ChromaCompat=yes"

Tool - in ChromaCompat mode.

375mW 445 = 26mW 532nm using the (1931 or 1975?) CIE tables from Chroma instead of the (1978?) values that were in there.
Beam: (445nm 375mw) vs. (532nm 26.17mw)

Maybe at some point I'll just add a drop-down so that people can choose the tables they'd prefer to use. I think that would confuse more people than it would help, but clearly there's a demand for different input data options, so I may give that some thought.

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#### qumefox

##### New member
Your missing the point.. 26mW of 532 IS NOT EQUAL TO 375mW of 445......

But I give up. Don't even look in to it and forget I said anything...

I'll keep doing it the 'old way' that has given *me* reliable real world results..

#### rhd

##### New member
Your missing the point.. 26mW of 532 IS NOT EQUAL TO 375mW of 445......
But I give up. Don't even look in to it and forget I said anything...
I'll keep doing it the 'old way' that has given *me* reliable real world results..
Calm down. Breath. Relax

That last post was my bad. When I added the URL toggle, I forget to change the code that updated the page title. So the calc value changed, but the page title that I based my reply on didn't:

With ChromaCompat ON:
Beam: (445nm 375mw) vs. (532nm 37.22mw)

#### Kevlar

##### New member
Whoa. Sorry for the thread jack DTR, it wasn't my intention to start an argument.

I think you guys are splitting hairs with this one. The difference in readings is only +/- 10%. That can be attributed to many things, such as everyone perceives wavelengths a bit differently or the variation in wavelength with the LD itself.

IMO both methods produce accurate enough results for the hobbiest.

DTR, I like your calculator. Its very handy, thanks putting it up for everyone! :beer:

#### wikemallace

##### New member
well i finally got all my parts for this build and assembled it today, it's AWESOME! I instantly threw on my super strong homemade laser safety glasses and started burning stuff..

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#### DTR

##### Well-known member
LPF Site Supporter

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#### DTR

##### Well-known member
LPF Site Supporter
I thought this deserved a little bump. I got a new one from Flaminpryo the other day with Yellow trits and it is pretty sick looking.

Notice the drilled holes have been coated black on the inside walls.

Got it all put together with a diode that has been waiting for this host.
Here are some sweet long exposure shots.:evil:

LPM test. With an O-Like lens.

Test with G-1.:eg:

Thanks Jeff. Great work.
:beer: