Welcome to Laser Pointer Forums - discuss green laser pointers, blue laser pointers, and all types of lasers



Galvos, and compatibility with Arduino

jtleniger

New member
Joined
Feb 3, 2012
Messages
4
Points
0
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

Well-known member
Joined
May 8, 2009
Messages
1,075
Points
83
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
 
Last edited:

Bionic-Badger

Well-known member
Joined
Oct 26, 2007
Messages
5,463
Points
83
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.
 
Last edited:

Things

New member
Joined
May 1, 2007
Messages
7,546
Points
0
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

New member
Joined
Sep 25, 2007
Messages
434
Points
0
Thank you Things, this has possibly got me off onto a new tangent :)
 
Last edited:

parimah

New member
Joined
Sep 21, 2013
Messages
7
Points
0
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?
 




Top