Diving into an RGB Projector

[DZ]

So I undertand now that I should stick with a 660nm red to achieve deeper colors. Got it.
But I also want this projector to be bright! So is there a place to get say a 600-700mw 660nm red that is of the same quality as the maxymod 440mw dual laser setup for not some insane price?

Here is a compairison I did a while back of 660nm and 635nm, both are 200mW:



David

[buffo]

I've talked to a few owners of 500 mw 635 nm diode lasers. They've all complained about the horrible beam quality. I've actually seen one in operation, and the beam was so large that it woudn't all fit on the galvo mirror! Plus, the divergence was so bad that at just 15 feet away from the projector, the beam was already a rectangle that was about an inch long and 1/2 an inch wide! (The rectangular beam profile was due to the mirror shape on the galvo... The rest of the beam spilled off the end of the mirror and was lost.)

Maybe someone makes a high power 635 nm diode that does have good beam specs. But my guess is that it's going to be quite a bit more expensive than a pair of Maxyz modules. (Then again, it will also appear brighter to the human eye than the 660 nm output of the Maxyz modules...)

The beam shows that I saw with the wide-beam 635 nm diode still looked pretty good, and even the graphics were sort of OK. I knew what to look for, so of course I spotted the wide beam, but I think the average guy on the street wouldn't notice.

Still, if it were me I'd stick with the better beam quality - even if I had to give up some power. But that's just me.

Adam

PS: I should mention that it seems to be only on the higher end of the power scale that this poor beam quality shows up. I've seen several lasers in the 100-200 mw category that have great beam specs, even at 635 nm.

[Matt]

Thanks for that visual comparison!



So if I get the lower powered 440 mW from Marconi would it look horrible to combine it with say a 200 mw green and a 300 mw blue? Just to get more umph.

Matt

[DZ]

Thanks for that visual comparison!



So if I get the lower powered 440 mW from Marconi would it look horrible to combine it with say a 200 mw green and a 300 mw blue? Just to get more umph.

Matt

It would probably look pretty good, though you really would not need that much blue to get a good color balance. My current setup is running (measured) 193mW of 532, 210mW of 635 and 183mW of 473. And it balances out nicely, a bit red heavy when I set the pallette for high power. But my green suffers the most loss since it travels through 1 bounce mirror and 2 dichros before it hits the scanners. The blue reflects off 1 dichro and travels through 1 dichro before the scanners. And the red reflects off of 1 dichro before the scanners.

David

[Matt]

But please remeber Dzerher
We are talking about useing a 440mw of 660nm

yours is relating color balance to a 635nm.


From what I gather the color balancing ratio differes from the two as 635 is much more visible than 660.

[DZ]

But please remeber Dzerher
We are talking about useing a 440mw of 660nm

yours is relating color balance to a 635nm.


From what I gather the color balancing ratio differes from the two as 635 is much more visible than 660.

Mett,

Your right, but, I have not tested this, but I assume that 440mW of 660 is pretty close to 210mW of 635 in apparent brightness.

David

[buffo]

Matt;

Have you looked at any of the pictures (or better yet, the video clips) from our little laser geek gathering (FLEM) in Florida a few months ago?

If not, I'll try to get an updated link to the video that was posted on Cruch's server. (The old link in the original post doesn't work now because he switched hosting providers.)

Anyway, Dave's red at 210 mw of 635 nm red looked only *slightly* brighter than Fred's 200 mw of 660 nm red. The two projectors were side-by-side for most of the day.

Color balance theory tells you one thing, but sometimes you need to throw that out the window and just go with what looks good. Would you believe my Avitar picture is just 14 mw of red (632.8 nm HeNe) with 10 mw of 532nm and ~30 mw of 488nm blue? If you do the math, it should look terrible, but it actually looks pretty cool. (Have a look at the white balance and see what you think.) Those pictures are 5 years old, btw.

Or, for a more graphic demonstration, have a look at this post. That's a full watt of 532 nm green, mixed with just 200 mw of 473 nm blue and 500 mw of 635nm red. (Not my projector) The math says the color balance is awfull, and indeed the system had a *TON* of green. But it still didn't look that bad.

Bottom line - color balance doesn't have to be *perfect* to look good. And it's always preferable to have some extra power available for beams. If you have analog blanking you can always dial the lasers back for those times when you absolutely need perfect color.

Adam

[DZ]

Anyway, Dave's red at 210 mw of 635 nm red looked only *slightly* brighter than Fred's 200 mw of 660 nm red. The two projectors were side-by-side for most of the day.

Adam,

Actually, that wouldn't be a very good compairison. Due to my original blue only doing 30mW most of that night, both my red and green were turned down to salvage at least some form of color balance between them. Now that I am up to 183mW of blue, my green is up all the way and I still end up a bit red heavy white if red isn't turned down a bit. I've been pretty happy with 635nm. At a distance the beam is trash for graphics, but great for beam effects. I havn't had to run graphics at more than 30 feet yet, but it doesn't look bad up to that point.

David

[carmangary]

That picture at the top of the page that shows the two red lasers doing the swirly pattern is the best comparison I have ever seen. It clearly shows the differences between the two much better than looking at just a projected dot or beam through fog. If we could get such a comparison for all wavelengths showing each beside each other at the same powers and then at power levels that make them look the same in brightness we could probably actually come up with some ratios that mean something.

[marconi]

Maybe, I dont know they look like red and red/orange to me
My avatar was done with a 35mW HeNe which looked red/orange to me as well..
It was pretty , but not red.
Its true , some people like the orangey/red color..its bright
but the color gamut will be less, you wont get red saturation.

But also important is spot size

Still , nothing like a nice Cherry red I guess Im partial to it... sorry.