Galvos, and compatibility with Arduino

[jtleniger]

I am doing a scanner project and this caught my eye:
20Kpps HightSpeed galvo scanner for laser lighting NEW (Without Show Card) | eBay

Do you think those galvos will have satisfactory quality? I'm not looking for anything really good, just a basic, basic scanner set up.

Second, would it be possible to control these with an Arduino?
They have analog 0 to 5v 490hz pulse width modulated outputs and digital on/off 5v outputs.

 

[LSRFAQ]

Second, would it be possible to control these with an Arduino?
They have analog 0 to 5v 490hz pulse width modulated outputs and digital on/off 5v outputs.[/QUOTE]


When the galvo has zero integration at the PWM frequency of the ardiuno, you will be unhappy with the ardunio. The galvo described will jump on each PWM pulse edge. You would have to integrate the pulses with a RC circuit, so Nyquist says you get at best 1/2 the PWM frequency as your frequency response, after the filter. So now your down to 250 hertz, or less out of the arduino. 1/250 = roughly on possible step every .004 seconds = Slow.
1/12 Kpps = .000083. .004 / .000083 = about 48 times slower then the galvo can scan, small angle.

Also the galvo takes signals both sides of ground, ground being 0 deflection. the arduino PWM is positive going only, so without a level shifter, you only get half the possible deflection.

If you can live with a very poor response and can tolerate using the RC integrator and the resulting phase shift in your images, you will be fine.

The galvos are fine, the Arduino needs its bootloader and interpreter erased, and you need to program it in assembly language or perhaps C to get any speed.

I think you will find most Mega series chips have two DACs on board, which would be far superior. Reprogram the Arduino in assembler, the use the onboard DACS. so its fast.

Galvos DO NOT like PWM.

Steve

 

[kiyoukan]

is this what your are looking to do?
Me & Mr. Cranky Pants Main/Open Laser Show DAC

 

[Bionic-Badger]

You'd need an XMEGA type AVR for any real DACs in Atmel's microcontroller series. The ATmega series, of which the Arduino uses, have only pseudo-DACs based on PWM. At that point you should seriously consider just switching away from Arduino altogether.

 

[Things]

Or getting an external DAC chip and controlling it from the Arduino. The TLV5618 (I think) is a nice dual channel DAC and has an Arduino library for it, though it is rather spendy at around $12 a pop.

 

[LaserCo]

Thank you Things, this has possibly got me off onto a new tangent

 

[parimah]

I am doing a scanner project and this caught my eye:
20Kpps HightSpeed galvo scanner for laser lighting NEW (Without Show Card) | eBay

Do you think those galvos will have satisfactory quality? I'm not looking for anything really good, just a basic, basic scanner set up.

Second, would it be possible to control these with an Arduino?
They have analog 0 to 5v 490hz pulse width modulated outputs and digital on/off 5v outputs.

i want to creat a square with laser,
i used two galvos for scanning,but i need info about frquency of galvo for make a square,do you have info?