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FrozenGate by Avery

How to know if is S or P polarization

C

CushCush

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Aug 21, 2009
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Hello dear Fellow

I am curios how could I know how is polarised the beam of my green 532 nm module...is P or S
I want to buy a second green module and a PBS polarised but I ask myself how is my actual beam module polarised P or S to know how to ask for the second module . How to find ?

Thank you
 





I'm fairly sure the polarization is random
unless the resonator has been designed with
a particular polarization state.
 
Another question is : Could be possible as my beam to be nor S and nor P polarisation ? I mean to be at another angle ?
 
So you want to combine two green lasers with a PBS? I think you need a 1/2 waveplate, some people here have built lasers that combine two lasers into one and they sometimes use a 1/2 waveplate in addition to the PBS. I don't know much about them so hopefully someone who knows more about this will say something here. Waveplates are used to control or modify the polarization state of light. Here is some more info on them:
http://www.edmundoptics.com/technical-resources-center/optics/understanding-waveplates

Alan
 
These half wave plates could be mounted directly onto the collimator of the module ? or how ?
 
Right in front of it I think, again I want to say I don't know much about these, I have never used one, so hopefully someone else will comment here.

Alan
 
They reflect light of the desired
polarization back into the resonator to
"seed" the oscillator. Again not sure
here, but I think it has to be the 1064nm
Nd emission. I'm not sure this can be done
after the OC. It might need to be part of
the resonator itself.

A good high power lab module should already
have this, though. Get some polarizing
filters and bounce the laser off a piece of
glass or several to reduce the power to a
usable level. Then use the filters to
determine the polarization state of the
laser and weather it is stable.
 
Ok but this filter hasn't some marks about angles to know about orientation . I will put it in front of my laser but how i will know at what degree is ...if is vertical or horizontal
 
I think I must to rotate this filter in front of my laser and some degree the beam will not pass but how to know exactly at what degree is happened
 
This is from Planters on Photonlexicon regarding a similar question about combining DPSS greens:

In order to increase the power of the green beam you can use a PBS and a wave plate (or rotate one of the DPSS heads 90 degrees) and combine two lasers. This has the advantage of increasing the brightness because the beam does not enlarge as with knife edging. However, you are limited to two lasers. Most, and possibly all, of the CN DPSS lasers are based on vanadate and are polarized. One exception is is the more powerful Laserwave modules. Here they have already combined two smaller units with a PBS within the head. The green diodes are also polarized and so you could mix a DPSS and a diode in a PBS as well.

You can knife edge DPSS heads as well as direct diodes and even mix a direct green with a DPSS. A little trick to these combinations is to include a steering mirror prior to the combining. This eases the requirements for mounting precision and makes the co-alignment more precise. Keep in mind that the more complicated the arrangement the more ways that optics can misalign.

I actually like the DPSS lasers because the power comes out of the head reasonably well focused (often this can be noticeably improved) from a mountable block with a compatible driver. I do not do mobile, professional work and so I'm not throwing projectors into the back of a van. These DPSS lasers have proved to be stable and reliable and cost effective. The choice as to which to use will change as time goes on.
Click to expand...
 
CushCush said:
I am curios how could I know how is polarised the beam of my green 532 nm module...is P or S
I want to buy a second green module and a PBS polarised but I ask myself how is my actual beam module polarised P or S to know how to ask for the second module . How to find ?
Click to expand...

S and P polarizations matter only with a reference to a reflecting surface.

With a rectangular housing as yours you talk about vertical or horizontal polarizations when the housing base is mounted on a horizontal table.

Even if you have no polarizer you could figure out with a glass plate. (break a window at least).
Steps:
1. Reduce laser power to the lowest possible operating safe level. Take cats and dogs and other friends out from the room. Safety first!!!
2. Insert a glass plate into the beam that it reflects on a horizontal plane.
3. Rotate the glass plate around the axis and observe the reflection. Make sure that the reflected beam is still on the same horizontal plane.
4. When the angle between incident and reflected beams is ~110 deg, you might see that the reflected beam diminishes (reduces power). That would mean the laser polarization is horizontal.
4B if not rotate your laser by 90 deg, and repeat the experiment.

If you want the theory read about Fresnel equations Fresnel equations - Wikipedia, the free encyclopedia , Brewster's angle Brewster's angle - Wikipedia, the free encyclopedia


Some 532 DPSS lasers have a bad polariztion ratio.
 
Thank you very much . I will try to find how is polarised my laser in this method :)
 
I talked with CNI peoples and they accept wire transfer . I don't know what to say but I am feel better via PayPal ... What you say about them ? Do I have trust that I will receive the package ? :) I want to buy some expensive stuff like some modules etc
 
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