Glued crystal alignment problems

[Stu]

I'm not 100% sure if this has been asked specifically before,if it has please delete/ignore,

I bought a $1 532nm pointer that is in my opinion really bright,
the beam will travel for what seems like miles,when pointed across the countryside at twilight it's visible dot can be seen on trees that are a good 2 miles away,so it's a good pointer.

since then iv'e been trying to build one to similar spec but using higher power.
where i am struggling is with the glued laser crystal alignment,the seller mentioned that the crystal had to be rotated 90deg but no matter which way i orientate the crystal i can't seem to create a beam as bright as the one that i bought for $1.
so iv'e opened up the $1 pointer and had a look at the crystal orientation (when the lasers off) through a magnifying glass and it looks like the crystal is flush to the diode block and that it's orientated on a 45deg angle to the diode,
is there a specific line of degree that a glued crystal should be aligned at in relation to the diode?
the crystal i have has 2 dielectric mirrors on the sides,does it make a difference which way these are facing? perhaps the attached image might help explain things better,
if anyone has any advice on glued crystal alignment i'd be extremely grateful,
thanks in advance,
Stu

 

[ultimatekaiser]

The alignment will vary crystal to crystal. Each crystal is unique however, and not all of them are just as efficient as the last, and the same goes for diodes. Not every one will give you the same results depending on the crystal's cut and coatings. Ten different crystals at optimal alignment are doing to give you ten different powers.

But it is also possible the other laser is giving more pump power, or something as well. (More likely)

 

[Stu]

thanks for the input,all that understood is there a rule of thumb for crystal alignment other than be patient with a steady hand?,
Is there an optimal zone where the crystal will perform better? (assuming the crystals have been properly aligned before being glued/cut)
cheers

 

[ultimatekaiser]

thanks for the input,all that understood is there a rule of thumb for crystal alignment other than be patient with a steady hand?,
Is there an optimal zone where the crystal will perform better? (assuming the crystals have been properly aligned before being glued/cut)
cheers

Depends on how in depth you want to get.... There's tons of variables that determine what your gain will be! But few of them you'll have control of in such a tiny space. The reason they suggested rotation, is that it will vary the polarization planes to optimal. But really to peak it, your eyes alone are generally not good enough. It takes specialized equipment and lots of knowledge of laser physics and practice even, to do properly.

for your case, the easiest thing to do is put it right up against the emitter like it was before, and then walk and rotate it till you get max output. That's about all the control you are likely to have, as you can't really reliably influence much else. Most optics do have slight sweet spots but being able to find them with your bare fingers is pretty much impossible due to the extremely small scale. Fractions of a mm or smaller matter here

If it was a lab laser or something though, there's about a hundred different things you have to keep track of

 

[Stu]

Thanks again for your input,
I will persevere and hope that i can find the best spot,
If i can replicate the set up from my $1 dollar pointer i'll be happy as that is really bright,time to get out the magnifying glass again and have another in depth analysis of the crystal orientation.
I knew it wouldn't be easy by hand but i do enjoy a challenge.
cheers

 

[ultimatekaiser]

Just be careful not to get the IR (or green) laser light in your eyes.

 

[Stu]

For sure,
iv'e had glasses since the age of 8 so i do try to look after my eyes,
static laser beams are very dangerous,whenever i'm tinkering with laser diodes it's always with an air of caution.