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ArcticMyst Security by Avery

lumens vs watts?

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probably discussed already and I suck at the search tool...

I know these are different units for different things, but is there some way to get a rough conversion from laser watts to lumens?

Say i want to add video to a laser show, can I know how many lumen laser projector I should get to use with a 1.5W laser projector running at 30K without getting few and making dozens of tests?
 





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You should know that watts is the unit of joules per second and lumens is the unit of lumenous flux. The former is used to quantify power, and the latter is used to quantify brightness to the human eyes, which takes into consideration of sensitivity of human cones and rods to different wavelengths. AFAIK there is no direct(accurate) conversion, since for every waveleingth ,the factor/conversion is different.
Correct me if I am wrong, old knowledge...
Hope this helps.
 
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https://spreadsheets.google.com/pub?key=rD0zIkgz3u1N28U9kPpl_hg

If we assume 1:1:1 ratio of 450/532/638, your projector is roughly 300-400 lumens. Of course, this brightness doesn't translate directly to that of a standard video projector, because one is vector based and the other is raster based. That's why we don't rate laser projectors in lumens, even though we could.
 
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Thanks for that!
So the final beam before hitting the scanner mirrors is 300-400 lumens right? What happens if I project 30K points at 30K scan speed? 30*30,000 lumens? Because to me if I lower scan speed and display less points with my laser the points are brighter than if I displayed more points.
And for deciding what video projector to use, do I need to divide the lumens of the projector with the pixel count?
 
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Thanks for that!
So the final beam before hitting the scanner mirrors is 300-400 lumens right? Because to me if I lower scan speed and display less points with my laser the points are brighter than if I displayed more points.

What happens if I project 30K points at 30K scan speed? 30*30,000 lumens? WTF lol the output of your projector stays at 300-400 lumens where are those numbers from

I don't think you got the units right
For clarity:

What I think you mean with the dots are brighter when you project less is:

lux = lumen/square meter = brightness per area

as you they in the equation when the area is smaller (less points) you have more lux but the output in lumen stays the same

watt = Unit of Power J*s = W

lumen = Unit of theoretical perceived brightness by human eye
simplified its power(Watt)*sensitivity at wavelength of the light = lm (lumen)


And for deciding what video projector to use, do I need to divide the lumens of the projector with the pixel count?


No just look at lumens for brightness and how big the area is you want to project on but for a video projector there are much more important things than brightness
 
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What happens if I project 30K points at 30K scan speed? 30*30,000 lumens? WTF lol the output of your projector stays at 300-400 lumens where are those numbers from
I meant 300*30,000 actually.
The beam is 300 lumens. if the galvos move it to 30,000 places in one second, our eyes will see 30,000 such 300 lumen points each second, so 300 lumen * 30,000 points = amount of lumens each second. This is where I got the numbers... Actually I should have divided that by 25, our eyes aren't updated each second.

simplified its power(Watt)*sensitivity at wavelength of the light = lm (lumen)
ok

there are much more important things than brightness
sure
 
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The beam is 300 lumens. if the galvos move it to 30,000 places in one second, our eyes will see 30,000 such 300 lumen points each second, so 300 lumen * 30,000 points = amount of lumens each second.

SXv8dMt.gif


Come on now. Did you even stop to think if that made sense? 10 million lumens from your tiny projector?

Moving a light source around doesn't make it brighter.
 
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I didnt say it made sense. I was asked where I got the numbers. I showed the logic. Doesnt mean i think that's correct, otherwise I wouldnt ask here.

Moving a light source around doesnt make it brighter, but using a galvo which moves faster than our eyes can catch up can cause that 1 point of laser to appear like 1000 points instead, and all as bright as that single one.
So a single beam from my projector is 300-400 lumens. What if i use my galvos and draw at 1000 points per 30th of a second, how many lumens will the projection appear to be? Thats my question.
 
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Moving a light source around doesnt make it brighter, but using a galvo which moves faster than our eyes can catch up can cause that 1 point of laser to appear like 1000 points instead, and all as bright as that single one.

That's where you go wrong :) Just imagine using the galvo's to 'create' 5 points from the single beam, and then some system of mirrors to redirect those 5 points back into a single beam. Suddenly, you'd have a beam 5 times as bright. Free energy! Unfortunately, not.

I'd say that if you use the galvos to split the beam up into X separate beams, they'll all be at 1/Xth of the original beam's strength.

(Actually, yes, every beam will be just as bright as the original beam, but since they're switched off while any other beam is turned on, they'll appear less bright to the eye)
 
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They are correct, no not all as bright as that single one. The answer to your question is 300-400 lumens. If it were that easy to amplify light someone would have built the death star by now.

Alan
 
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What if i use my galvos and draw at 1000 points per 30th of a second, how many lumens will the projection appear to be? Thats my question.

Since you now know that moving a light source does not make it brighter, I'll tell you what the scanners do. The scanners move the light source. That is ALL the scanners do. Does that answer your question?
 
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Since you now know that moving a light source does not make it brighter, I'll tell you what the scanners do. The scanners move the light source. That is ALL the scanners do. Does that answer your question?
No , not really...

I'm not saying the light becomes brighter. Im saying (well asking) that if the scanners move the point of light so fast it appears as 1000 points, doesnt each point *appear* as bright to our eyes as the actual, "real" single point? Apparently no, ok.
 
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https://spreadsheets.google.com/pub?key=rD0zIkgz3u1N28U9kPpl_hg

If we assume 1:1:1 ratio of 450/532/638, your projector is roughly 300-400 lumens. Of course, this brightness doesn't translate directly to that of a standard video projector, because one is vector based and the other is raster based. That's why we don't rate laser projectors in lumens, even though we could.
I'm not sure how to use the data from that spreadsheet. Can anyone help?

So far I get I have to take the wavelength of my diode. Then what? What is "Relative Eye Response"? And "Lumens Per Watt" is seems so low, maybe I don't understand what this is too: a laser point on a wall from a 1Watt, 445nm laser diode is 20 lumens? Please help to understand all this.
 




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