Red + Green = no Yellow?

[White-Light]

@Lloyd you want 637 or 640 or 642 for good beam specs. 635 and 650 are usually very fat although I think Andy Con said he has a way of taming 650m. Personally I'd still go for the others because they natively slimmer and have a visibility advantage over 650nm.

Edison on here builds 637 modules commercially and him and several other people on here build 445nm commercially. Alternately you can buy a big branded version of these wavelengths.

Forget 473nm unless you're feeling rich and buy 500mw of 445nm blue as its dirt cheap. Some of us like 473nm but its its horses for courses. Both 473nm and 445nm each have their own advantages (473nm bright colours, 445nm dark colours, icy white and price), but the biggest factor with 445nm is price.

A ratio of 1:1:1 works for most people with 640/637 : 532 : 445. Given the size of your other modules you might end up over blued but its ok.

[gottaluvlasers]

635, 650, 660 are all diode "stripe" type red lasers. Which means *HORRIBLE* beam profiles. If you want reds with good beams to closer match the profiles of your green and blue then go with 637, 640, 642 or 671. (671 is a DPSS laser like your G and B.) What you are seeing in your beams is perfectly normal. However, they do look a little bit misaligned.

Also, remember- you are looking at a static beam up close. once that beam begins to move around it will appear to be much more yellow.

-Marc

[lloyd33]

Thank you, gottaluvlasers. I am just now realizing the sad truth about
the diode array / stripe setups inside these laser heads. They don't seem
terribly useful. Does anybody actually use these in RGB projectors? That
is also very interesting about the 671 nm being a true DPSS laser. I had
often wondered about that. So basically 637 nm, 640 nm, and 642 nm
are all single diode / single point sources that you can make decent beam
profiles from (you just might need to double them up), right?

Live & learn, I suppose. 250 mW red laser up for sale.. any takers?

[colouredmirrorball]

Uhm, if the price is good, yes!
I like bad beam quality, bigger beams = safer shows. My blue is horrible and I like it!

[Stoney3K]

As an alternative, you can always expand the green instead of trying to squash the red.

[lloyd33]

@ Stoney3K, working on that now. Expanding the beam was pretty straight-forward.
Adjusting the output power via the analog modulation is proving a bit more difficult.
I am trying to find a simple circuit of some sort that would maybe let me use a
potentiometer to adjust the analog input from 0 to 5 volts DC. But there are so
many things I am confused about, such as how to limit the amount of power that
gets to the potentiometer and / or laser power supply without blowing everything up.
Those seem like prudent first safety steps.

[swamidog]

lloyd33,

put a 10k ohm potentiometer on the 5v modulation input. that's all you need.

@ Stoney3K, working on that now. Expanding the beam was pretty straight-forward.
Adjusting the output power via the analog modulation is proving a bit more difficult.
I am trying to find a simple circuit of some sort that would maybe let me use a
potentiometer to adjust the analog input from 0 to 5 volts DC. But there are so
many things I am confused about, such as how to limit the amount of power that
gets to the potentiometer and / or laser power supply without blowing everything up.
Those seem like prudent first safety steps.

[lloyd33]

My understanding is that those can only dissipate ~ 1 watt of wasted energy.
The lasers are running off a Sorensen DLM 5-75 power supply (5 volts DC @ 75A).
So.. I would need a separate 5 volt DC power supply that outputs 200 mA max. ?

Unless you know a way I can use all that extra current to create a simple current
limiting circuit. This is the part where I get confused and my head spins around.

[swamidog]

no. the modulation input will take only as much current as it needs and it needs very little. it should be on the order of mA.
remember, you're only doing this on the modulation input, not on the laser power input.

why don't you post some photos of your setup up so we can verify. i would hate for you to accidentally fry something.

My understanding is that those can only dissipate ~ 1 watt of wasted energy.
The lasers are running off a Sorensen DLM 5-75 power supply (5 volts DC @ 75A).
So.. I would need a separate 5 volt DC power supply that outputs 200 mA max. ?

Unless you know a way I can use all that extra current to create a simple current
limiting circuit. This is the part where I get confused and my head spins around.

[Stoney3K]

@ Stoney3K, working on that now. Expanding the beam was pretty straight-forward.
Adjusting the output power via the analog modulation is proving a bit more difficult.
I am trying to find a simple circuit of some sort that would maybe let me use a
potentiometer to adjust the analog input from 0 to 5 volts DC. But there are so
many things I am confused about, such as how to limit the amount of power that
gets to the potentiometer and / or laser power supply without blowing everything up.
Those seem like prudent first safety steps.

Trimming the modulation input is easy:

Place the fixed ends of the potentiometer between your (old) modulation input that now connects to the DAC, and ground. The other wire on the pot, the wiper contact, will be your new modulation input that connects to the laser. Simplistico ASCII-arto:

MOD IN      o----+
(from DAC)       |
                 =     
                | |
                | |<--o MOD OUT (to laser)
                | |
                 =
                 |
GND         o----+----o GND

You can take any potentiometer you want, anything around 10K is a reasonable value. Get one with a knob if you want quick coarse control, or one with multiple turns if you want a finer control over power and want it to stay there.