The Laser Project.

[Tweakie.CNC]

It's only a baby Dan, weighing in at 25 Watts.

Tweakie.

[Dan13]

Ah... Looks like a monster on the photo  ...

Dan

[manmeran]

Tweakie
is it possible tell price?

Amir

[Tweakie.CNC]

Amir,

Second user they go at about $500.

http://cgi.ebay.com/Synrad-25W-CO2-Laser-Model-F48-2-285W-Great-Condition-/300456367802?pt=LH_DefaultDomain_0&hash=item45f49856ba

(all I need now is the galvo head  )

Tweakie.

[manmeran]

i agree for GALVO head 

Amir

[Tweakie.CNC]

I have not yet decided just how I will be controlling the Synrad RF laser but whatever system I use i am going to need a 'tickle pulse' generator so at least this is one part I can start making already. The required circuit is extremely simple and I like simple.

The 'tickle pulse' generator has to supply a stream of 1uS pulses repeated every 200uS  (5kHz) and this keeps the gas on the point of lasing and in readiness for the trigger or firing pulse which will in turn be a pwm stream ranging from 10% to 100% mark space ratio.

The finished controller will be modular in construction and this little pcb will just be incorporated into the main pcb (at least I think that's the way it's going to go).

This little pcb has been isolation routed, now to solder on a few components and test it out.

Tweakie.

[Tweakie.CNC]

Components added to the pcb. Fired it up and as luck would have it, worked first time.  

This circuit takes advantage of the hysteresis in the switching characteristics of the 74HC14 inverter IC.
One gate is used to create a 5kHz square wave oscillator with the output charging a capacitor which is in turn discharged by a resistor the time constant of which creates the 1uS pulse through a second gate which is finally inverted through a third gate. Simple.

The upper trace shows the 5kHz oscillator output.
The lower trace shows the 1us pulses repeated every 200uS which is exactly the requirements for the Synrad 'tickle pulse'.

I am still undecided about the controller design but this circuit will at least allow me to test the laser to check that it does indeed work.

Tweakie.

[Sam]

Neat stuff you get yourself into, Tweakie. I wish I had some of your electronic know-how. How is this laser better than the one you currently have?

[Tweakie.CNC]

Hi Sam,

I don't really think it is any better although in industry the RF energized type are preferred over the DC energized type (not sure why).
It is just different to what I have already - and it was a bargain I just couldn't resist. 

It operates at 30 Volts rather than 16,000 Volts and is probably a lot easier to control by PWM and CW without electrocuting myself.
The output is polarized which could be an advantage with some applications but may be a disadvantage with others.

Amir was talking some time back about galvo, raster scanning lasers and this could be the starting point for me to build one - anyone know where I can obtain a 70mm ZnSe F-Theta Ronar lens real cheap ?. 

Tweakie.

[manmeran]

cheap

i am sorry