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How to deflect a laser beam??

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Bus Master

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Hi there,

The only method to deflect a laser beam is via a mirror. Trying to automate this operation will guide to one of these two common tricks:

1) fix the mirror to a motor (eg. Stepper).
2) fix the mirror to a speaker (eg. subwoofer) and apply a frequency. [This method lacks position control accuracy].

Is there any other method to deflect the beam?

I'm trying to design a laser scanning system as used in the CRT.

Any comments are highly appreciated.

Thanks in advance.
 

flatulent

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eledtro optic

Electro optical modulators have crystals whose index of refraction varies with electric field applied to it. You could make a prism of this material and apply the electric field to two surfaces. I suspect that the angle change would not be large and you would have to project your beam a long way to see any significant displacement. Or perhaps, a whole path of prisms to multiply the effect. What if you had a tunable laser and use a dispersive material for the prism?
 

Hishamsaleh

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send email to :
holzhey@iapp.de
he is physics scientific.. and he works on laser project.. as i remember he tald me that he works on 20w beam power!!!! his name is Andre.. from Germany.
 

cube007

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For proffessional deflection of a laser beam you will need a scanner (x,y galvanometer). E.g. these devices are used in lasershows and are not cheap. A x,y pair costs about EUR 1500.

Sometimes there are some good offers in Ebay.

If you wish I can give you some URLs of german sellers.

By,
cube007
 

wolf69

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if you have a gravity source you can deflect the laser beam with it... hehe.. joke but true!
Bye All
 

junglejenny

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Perhaps you should ask: how to build a gravity device.
Until someone comes up with that method, It is not clear from your question what degree of deflection you need.

You could mount a mirror on a speaker and shine your beem at it. by applying different voltages to the speaker, you would get different results.

JJ
 

Rainbow Wizard

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There are many many ways to deflect a laser beam. In the frequency range you are working with, however, galvanometers with little mirrors mounted on them (already been mentioned in this thread) are not a good option. They tend to be slow -- 1 to 10 KHz max.
There are also piezo-electric and magnetostrictive materials that can drive a small mirror or a diffraction grating and they can get up to 25- 50 KHz typically. Piezos are cheap and may do the job for you if your horizontal scan rate is not too high.
Electro-optical crystals come in many compositions and can get up to about 50 - 100KHz (check out PLZT crystals - there is an interesting website at MIT.edu). Some types of crystals can get much higher, but they get quite pricey. Kerr cells are fluid-filled, rectangular quartz glass cells with ITO electrodes on the transmissive surfaces. They can modulate a laser beam quite rapidly, but you need a high driving voltage.
Last, there are acousto-optic modulators. These are polished piezo-electric crystals on the surface of which a travelling wave is induced through application of appropriate AC currents. The waves then deflect an incident laser beam in a pattern, usually a 1 dimensional raster. So for 2D scanning, you need two of them. Sounds tricky, but they have been around commercially for a long time (used in laser printers, etc.) and so they are not too expensive.
The problem is really with the horizontal scanning direction which usually has to be pretty fast. The vertical is much slower and you can use a variety of technologies to do it, (icluding a speaker with mirror glued to it, if you operate it closed-loop!!)
There are also some MEMS devices recently coming out of the labs, but I am not sure whether they are commercially available yet.
You might try taking the guts out of a laser printer for the horizontal scanner.
Check out http://www.spie.org/. You can do a literature search through their EXTENSIVE library of research materials, and you will find much info on this topic than you would like <grin>.
 
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