correcting 445/450nm and 462/465nm beams together?

[Finale]

I've gotten my hands on one of those 445/462 dichroic mirrors. I m thinking of combining the NDB7875 and NUBM07E diodes this way and was wondering if I should use two sets of cylindrical lenses for correcting the beams individually or if the small difference in wavelength would make it okay to correct the two beams combined with the prism together with one set of lenses?

[polishedball]

It's more the beam profile than wavelength. I have used 1 set of correction in the past after the pbs cube and gotten good enough results. But you will need to wave plate one as you can't rotate the polarization

[Finale]

It's more the beam profile than wavelength. I have used 1 set of correction in the past after the pbs cube and gotten good enough results. But you will need to wave plate one as you can't rotate the polarization

Why do I need to rotate the polarization and polarization of what diode? Do you mean the polarization of NUBM07E and NDB7875 are different?

[CDBEAM]

I have also used a single set of 6X Cylindricals to correct the NDG7475/NUBM07E diode combination with very good results.
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It does not matter what LD you rotate the polarization/EM field on...Pick one.
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OK..to get the best match up...the best Beam-on-Beam ( BoB)....the nearfield geometry of both beams..... must enter the PBS cube with the fast axis being perpendicular to your optical base plate/plane.
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This means that the geometry that you need to see on the entry surface of the PBS cube is....
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a small vertical bar...going up/down on one (1) entry side.....Let us call this the " Main Beam " and....
a small vertical bar...going up/down on another entry side... which is right next to the " Main Beam " side.....Let us call this the " Secondary Beam " . These entry sides are at a 90 degree relationship to one another.
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You will see a plane within the PBS cube...This is where the two prism's that make up the PBS cube are joined. On this internal plane....both beam geometries....( The Main Beam and the Secondary beam) must be over layed ...or...in a Beam -on- Beam state to accomplish optimal beam combination / alignment. BUT.....but...
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For the PBS cube to be able to combine the beams...the polarization of one (1) beam must be at 90 degree to the other beam. Well....to rotate the polarization....you only have two (2) options; 1) Physically...rotate the LD, 2) Leave the LD alone....and use a waveplate filter to optically rotate the polarization field by 90 degree.
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You cannot rotate the LD....for that would cause you to lose the BoB condition/state.....SOoooo....you place a Waveplate optic in the beam bath of one of your diodes...again....it does not matter which one....Green or Blue.....the photons do not care ...HAHAHA
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Now....with the waveplate in place.....you must rotate this waveplate in an radial fashion...rotating the optic about it's central axis to locate the best radial position. This best position is determined by using a Power Meter and rotating the optic. The position at which you achieve the greatest optical power of your Secondary beam as it propagates out of the PBS cube.....is the where you want to lock down your waveplate optic.
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When the waveplate is in the best position....you have rotated a single beam Polarization by 90 degree....but have not changed the beam nearfield geometry....and this is what you want.....SOooo....now....both beams enter the PBS cube.....with the fast axis perpendicular to your optical plane ( " l " bar shape going up/down )....and...because you've rotated the Electromagnetic Polarization field with the wavelate....the PBS can now combine your beams.
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Now....as the combined beams exit the PBS cube....they then prop into the Cylindrical Lens set. AND...a big AND...both beams are in the correct orientation for the Cylinderical lens set to expand the slow axis....so...This " l " becomes this " # "... and the C-Set corrects the astigmatic beam geometry. Out pops two (2) corrected beams....with a close to 1:1 aspect ratio....closer to a circle...again...not a perfect Gaussian circle....but....for our purposes....very good for projector application.
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Hmmm...Do I get paid by the word ???? I hope all the above makes sense....if not...refer to Beam Axiom #2
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Happy New Year...to all you "Photon Phanitics"
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CDBEAM

[clickamouse]

Excellent description!

...Mike

[polishedball]

Excellent description!

...Mike

Clearly your talking about my one liner .

[norty303]

I've got modules with the NDG7xxx 462 and 445 diodes that are cubed and corrected by a single set of prisms. Works very well

[CDBEAM]

Well...I did get a bit carried away with my explanation.... Mr.Finale is either :
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Stunned with such superb reply.
Completely confused by all the Blah,blah,blah.
Is overloaded with too much info....and wonders...." Who the Hell writes all this for a simple question ?? "
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In any case....someone may find this explanation useful !!
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Also...I believe the nomenclature...BoB (Beam - on - Beam) is a new phrase....that Terrawatt gets credit for.....she is a real " Word Wizard " of a dog !!
If anyone finds any flaw in my explanation.... PLEASE do point these out....and I will be sure that Terrawatt corrects the flaw !!!
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CDBEAM

[Finale]

Just a bit confused thats all.
I understand what waveplates do , they rotate the polarization or the "invisble angle" of the light which is required for PBS combining to work. I don't understand how that affects combining 445/450 nm and a 462/465nm diode or module with a dichroic mirror, which is what I was asking. Or rather that's what I was trying to ask, after reading this response:

It's more the beam profile than wavelength. I have used 1 set of correction in the past after the pbs cube and gotten good enough results. But you will need to wave plate one as you can't rotate the polarization

Maybe I didn't understand this answer...

[polishedball]

Just a bit confused thats all.
I understand what waveplates do , they rotate the polarization or the "invisble angle" of the light which is required for PBS combining to work. I don't understand how that affects combining 445/450 nm and a 462/465nm diode or module with a dichroic mirror, which is what I was asking. Or rather that's what I was trying to ask, after reading this response:



Maybe I didn't understand this answer...

Those wavelengths IMO are too close to combine with a Dichro. The wavelength drift with temperature I think would cause a huge loss if this could be done. I went crazy combining 405 and 473 on one at one time. The angle need to be perfect etc. Who's dichroic mirror are you planning on using? I'd be interested to see the spec sheet.

It would be much easier to consider using the PBS cube and waveplate method