Combining RGB DPSS

[buffo]

as far as a polarization problem goes, it should not be terribly sensitive to that

Exactly. Polarization is irrelevent here. I don't know where Bridge was coming from; it might be the language barrier affecting things here, but dichros are not polarization-sensitive. (They are angle sensitive, however.)

My guess is that either the original dichro was junk to begin with, or it was damaged somehow - either when you pulled it or when you re-mounted it. But dichros are not all *that* fragile... (You didn't clean it with a harsh solvent or use an abrasive cloth on it, did you?)

The other possibility is what Aaron mentioned: in the process of removing and re-mounting the dichro you accidentally flipped it over. Try reversing the dichro before you buy a new one. (Might be a good idea to play with the angle a little bit too - sometimes a small shift in adjustment angle can have a significant effect. Not 50%, but still...)

kinda silly to spend thousands on lasers to get every available mW dpss technology can offer for the $, and throw away half the power through cheap a$$ optics.

Well put. Quality optics are still cheaper than higher-power lasers. Hope you get it resolved though. Post pics of your rig when you get it running!

Adam

[bridge]

Exactly. Polarization is irrelevent here. I don't know where Bridge was coming from; it might be the language barrier affecting things here, but dichros are not polarization-sensitive. (They are angle sensitive, however.)

My guess is that either th+6+e original dichro was junk to begin with, or it was damaged somehow - either when you pulled it or when you re-mounted it. But dichros are not all *that* fragile... (You didn't clean it with a harsh solvent or use an abrasive cloth on it, did you?)
Adam

Nice discussion!
When the light incident with 0 degree,We don't care whatever polarization state the laser is. but with other degree,especially big degree,in coating design,we must consider the incident degree.
So I meaning is the better dichro must consider the polarization and incident degree,before coating.

[illuzion]

I did not damage the dichro, I pulled it from the chassis with the mount, I planned on using the dichro on their cheap mount, so there was no need to dismount/remount it. I did not clean it, I did not heat it, or do anything to damage the coating. I finally broke down and ordered some thorlabs kinematic mounts, and I will try to order the dicros from EO today. Prolly should have done that in first place. The only difference between my unit and the one it came out of is power. The RGB these were pulled from is a 200mW total unit, and the blue was only like 40mW. I am pumping 200+ mW into it, it is possible the coating is thin, and cannot handle the power density. There are no visible signs of damage to the dichro though.

[JimBo]

I've just gone through the post again and you don't mention anything about IR filters. If there is no IR filter on the blue you will experiance these magnificent losses in measured power.

Jim

[illuzion]

Normally i would agree with you on the IR filter issue, except for the fact that there is a BRIGHT VISIBLE blue beam transmitted through the optic, about as bright as the one that is reflected, and both beams measure close to same power levels, 120mW vs 90mW.

[JimBo]

Good point, I missed that

Jim

[illuzion]

As a note I agree with bridge that a dichro is sensitive to incident angle, and its center filter wavelength can vary with incident angle, but I really don't think polarization plays into it (at ANY incident angle). Now I have another question. It is obvious I need a blue dichro to reflect blue and pass blue/green, and a red dichro to pass green and reflect red, but EO also sells a green dichro, I was wondering if there is any advantage to using this instead of a regular mirror to reflect green?

[JimBo]

I expect the dichro will be more expensive than a mirror, so if needed I'd use the mirror.
My preference would be to not use anything on the red and have it pointing directly at the galvos, then combine the red with the green with a dichro and finally the blue with the red/green.

Jim

[buffo]

I agree withi Jimbo: Why use a dichro when a mirror is cheaper?

However, with regard to the order of the lasers in the beam path, I suggest a change...

Red photons are precious, because they're hard for the eye to see (so you need more of them) and beyond a certain power level (about 500 mw) it becomes prohibitively expensive to create more of them. Blue photons are even more expensive to make, and are still difficult for the eye to see (but not as bad as red). Green photons, on the other hand are cheap, easy to see, and plentiful. Therefore, I suggest you put your green laser as the first one in the chain. That way the green beam is the only one that has to pass through two dichros (and thus suffer a few percent power loss through each one). You don't really care, because it is cheap to add a little extra green...

The decision for the next laser in the chain would depend on how powerful your blue and red lasers are. If you're looking for good color balance and you're coming up short on blue, then put the blue laser closest to the scanners. On the other hand, if you're already right at the limit of what you can get out of your red (say you have 2 maxyz modules combined and only have 400 mw, but you need more), then put the red laser(s) closest to the galvos and put the blue in the middle. True, blue photons are very expensive, so you hate to waste any of them, but if you want good color balance, you might need to go this route.

Adam

[JimBo]

I did meen green-red-blue, thanks Adam

Jim