Need cheap beam expander?

I need one the ceap ones from DL i found are still over my budget for small experiments.  

I hear that binoculars work and test it, it work fine.
But i dont want lasing around with my big binoculars.
DX has cheap monoculars, for 13 i get this one:
http://www.dealextreme.com/details.dx/sku.3323

First i think about alloy adapter maybe with setscrews.
But this will scatch my lasers i scary about.
I choose black plastik and lathe tight fitted sittings in the adapters and the laser.
It work its centerd enought and dont fall down.
Sorry for the pictures dslr i have not on hand right now.






The blu has 130mw output with its aixis lens, for the pic i have to use some smoke.


THe green one is a bit offcenter, the adapter fit tight but its mounted on the fokus optik from the laser and this is problem from the wobbling of this fokus thread.


I have a bit scatter around the dot its from internal reflections from the monocular?
For this 13 USd its not great lenses, its a lightwight thing maybe plastik lens.
I think this coast some mw.

I guess the real beam expanders are way better at efficiency and beam quality.
For playing around its nice.  


Daniel

Nice mod, I'll be looking into this!

Nice solution...

But how did you manage to use it on the blu ray? Those usually have pretty thick beams to start with from their aixisz modules (5mm diameter or so). For a 8x20 optic the maximum input diameter can be 2.5 mm, anything else will be lost (even if the input lens is much bigger than 2.5 mm).

First test i do is with my Roithner Lens 27 this beam is thinner then 2,5 mm.

But to tell the truth i dont know exactly what this 8x20 say!!

I can imagine that the beam is spreaded more bigger(at the first lens) then the barrel diameter because i notice some distortion around the main beam. The result are these rings from internal reflection from the monocular technik i guess.

I try to show you this with my mobilephone camera, its not looking like in real life because the center is overexposed alot.
In RL the center is a nice round dot with sharp boarders. Sourronded by this "rings"
For this picture i use windowd aixis plastik lens because the beam quality is better then with the Roithner.
!!The roithner take the complet beam wich is not round by his nature!!! (main reason for the power increase with roitner)




For the blu ray its also possible to use no lens, put it direkt on the diode, this work, i get a collimated beam, but i think the loss is big because a part of the emited beam is lost in the tread from aixis because of the emiting angel from diode!

If i use no lens bevor the expander thing i have to use complet different zoom position for sure.


daniel

I hope i found the time this evening to measure the output in a spezific distance without expander and with expander dot collimated to same size like without.

Just to allow me a guess how high the loss is. : :-?


Daniel

But to tell the truth i dont know exactly what this 8x20 say!!

Click to expand...

It means 8x magnification, with an input lens of 20 mm diameter. Logically, the maximum output is 1/8th of 20mm, so 2.5mm.

In this application input and output are reversed ofcourse.