Mixing 635nm and 660nm

[dave]

Does anyone know where i can get a suitable dichroic to combine these two wavelengths?

[allthatwhichis]

Damn... That's like splitting hairs there... Or combining them. :roll: Could you take a cube like marconi does and take one of each polarization? (ignorant guess)

[Spec]

I've been trying to find/produce optics with that narrow of a response for quite some time... It all started with this idea:



There are some narrowband mirrors like that, but they primarily live in the IR band and even then they dont "pass/reflect" they "pass/absorb" the respective frequencies.

I get lost thinking about a thin film that is that narrow

Basically right now your only option is to use a PBS cube and combine P/S that way, but your are severely limited by the output powers attainable by diodes capable of producing that frequency and beam shape characteristics.

[dave]

How does RGB lasers do it? Maybe Yadda can answer?

[Spec]

Thats funny, I was actually looking in his gallery at the teardown pictures trying to figure that out as you replied.

It almost has to be a dichro, though if past experience with the Arctos units has taught me anything, its that nothing is sacred when it comes to creative optical combining techniques.

I'm going to post a feeler to sci.optics and see what happens.

[dave]

Hmmm,

RGB lasers cant use a PBS, as both reds lack polarization.

It sure looks like a dichro..

[buffo]

It might be easier if you swap the order of the last two beams.

Right now you've got it set up such that your final dichro needs to pass 473 and 532, reflect 635, yet pass 660. I think it would be easier to find an optic that will pass 660 and reflect everything from 640 on up, and make that the last dichro in the chain. Then, for the 635 nm line, get a dichro that will reflect 635 and pass everything else.

Basically, the point is that up until you add the 635 red, every dichro in the chain only has one critical wavelength to worry about. But when you put the 635 nm laser at the end, you force the last dichro to be a sort of notch filter in that it's got two critical wavelengths - both the longer 660 nm AND the shorter 532.

Also, just for the sake of discussion, I wonder what 30 + mw of 405 nm would look like if you added it to the mix? Any effect at all you think?

Adam

[dave]

Also, just for the sake of discussion, I wonder what 30 + mw of 405 nm would look like if you added it to the mix? Any effect at all you think?

Adam

After seeing the Arctos RGB's in action, the deep blues and purples are out of this world.. I think Arctos use ~440nm diodes tho..

Oracle over here has custom Arctos units with dual scan heads.. I hate to think what sort of investment was made...

http://www.oraclelaser.com.au/2004/p...r2/septor2.htm

[eyceage]

It might be easier if you swap the order of the last two beams.

Right now you've got it set up such that your final dichro needs to pass 473 and 532, reflect 635, yet pass 660. I think it would be easier to find an optic that will pass 660 and reflect everything from 640 on up, and make that the last dichro in the chain. Then, for the 635 nm line, get a dichro that will reflect 635 and pass everything else.

Basically, the point is that up until you add the 635 red, every dichro in the chain only has one critical wavelength to worry about. But when you put the 635 nm laser at the end, you force the last dichro to be a sort of notch filter in that it's got two critical wavelengths - both the longer 660 nm AND the shorter 532.

Also, just for the sake of discussion, I wonder what 30 + mw of 405 nm would look like if you added it to the mix? Any effect at all you think?

Adam

I agree. Put the 660 last.

Dichros are basically angle-sensitive band-pass filters. You can easily pass 635 while reflecting 660 (or vise-versa) by adjusting the angle of the optic. You'll probably need to be off from 45 degrees, but it should work fine.

An IR filter is the same thing. We use them on camera CCDs at my work here. They're designed to be used flat and block IR, but if you adjust the angle you get get them to block (by reflecting) visible red wavelengths. You can "set" the threshold wavelength simply by changing the angle of the optic.

[aijii]

Easy huh ?

So find somebody that makes the filters then

Wonder if edmund could help out here...