Old 04-20-2017, 09:47 AM #1
Junior Member
 
Join Date: Oct 2016
Posts: 3
Rep Power: 0
gigi2 is on a distinguished road
gigi2 gigi2 is offline
Junior Member
 
Join Date: Oct 2016
Posts: 3
Rep Power: 0
gigi2 is on a distinguished road
Default Laser driver circuit

I like to build a laser pointer driver circuit that I can drive from an 8 bit uC. However, I like to get light output fairly constant. This requires for me to look at the photo detector (these lasers come with 3 pins, gnd, laser cathode, pd cathode) current and adjust laser input current to stabilize light output.

Ideally, I need to drive this from a GPIO of 8bit uC so that I can make it oscillate at different frequencies at different times. (100-300Khz range nothing very fast) I looked around and the analog circuits that are available are for DC, I couldn't come up with a way to drive them from GPIO.

I want to ask masters here, is there a way to do this with a few transistors etc. if not, what type of ICs I can use for this purpose. (A simple current driver with some feedback perhaps?)


gigi2 is offline   Reply With Quote










Old 04-20-2017, 12:18 PM #2
Class 1M Laser
 
Join Date: Feb 2012
Location: Sydney, Australia
Posts: 178
Rep Power: 1273
Mosc007 has a reputation beyond reputeMosc007 has a reputation beyond reputeMosc007 has a reputation beyond reputeMosc007 has a reputation beyond reputeMosc007 has a reputation beyond reputeMosc007 has a reputation beyond reputeMosc007 has a reputation beyond reputeMosc007 has a reputation beyond reputeMosc007 has a reputation beyond reputeMosc007 has a reputation beyond reputeMosc007 has a reputation beyond repute
Mosc007 Mosc007 is online now
Class 1M Laser
 
Join Date: Feb 2012
Location: Sydney, Australia
Posts: 178
Rep Power: 1273
Mosc007 has a reputation beyond reputeMosc007 has a reputation beyond reputeMosc007 has a reputation beyond reputeMosc007 has a reputation beyond reputeMosc007 has a reputation beyond reputeMosc007 has a reputation beyond reputeMosc007 has a reputation beyond reputeMosc007 has a reputation beyond reputeMosc007 has a reputation beyond reputeMosc007 has a reputation beyond reputeMosc007 has a reputation beyond repute
Default Re: Laser driver circuit

You could do it all from your Micro. Send a digital PWM output to turn the power on to the diode. Then have an analogue input for current feeback into the Micro. Adjust the PWM output to get the current you want. Problem is your program needs to react fast enough. Current feedback loop.

Then the Photo Diode also needs to be an analogue input to the Micro. And adjust your PWM output to control it.

What I would suggest is an Op Amp current regulator. Then you can send an analoge current ref from the Micro to the Op Amp which is controlling the current well. And the analogue Photo diode input so you can adjust the level.

All doable. But could be fun.
__________________
650nm Custom Module. 200mw
638nm Custom Module. Mitsi. 500mw
633nm Melles Griot HeNe Lab. 1mw
532nm Module in Jayrob host. 90mw
532nm Commercial Laser Module. 80mw
520nm Custom Module. 910mw
462nm Module. S4X Host. M462. 2050mw
450nm Custom Module. NUBM44. 8300mw
450nm Commercial Engraver Module. 2000mw
445nm Custom Module. M140. 1400mw
405nm Custom Module. 16X BR. 500mw

Last edited by Mosc007; 04-20-2017 at 12:19 PM.
Mosc007 is online now   Reply With Quote
Old 04-21-2017, 12:13 AM #3
Cyparagon's Avatar
Class 4 Laser
 
Join Date: Sep 2007
Location: Wisconsin
Posts: 9,080
Rep Power: 5350
Cyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond repute
Cyparagon Cyparagon is online now
Class 4 Laser
Cyparagon's Avatar
 
Join Date: Sep 2007
Location: Wisconsin
Posts: 9,080
Rep Power: 5350
Cyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond repute
Default Re: Laser driver circuit

You've left out perhaps the most important info here. Why do you need a laser at 100-300khz, and why does a micro need to be involved?
__________________
A problem well stated is a problem half solved.
Cyparagon is online now   Reply With Quote
Reply





Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On











Loading












Privacy Policy | Advertising Disclaimer | Terms of Use


 


All times are GMT. The time now is 08:37 AM.


Powered by: vBulletin
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
Search Engine Friendly URLs by vBSEO
Privacy Policy | Advertising Disclaimer | Terms of Use
Copyright (C) 2017 Laser Pointer Forums, LLC