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



100 microsecond pulse with green laser 303 pointer

Canozcan

New member
Joined
Jun 29, 2020
Messages
3
Points
1
I am trying to get a 100microsecond long light pulse from a laser 303 pointer. I am generating a square wave input voltage pulse via arduino to drive a mosfet which controls the voltage supply to the laser 303. I do not get any light out of laser 303 with this setup. If I increase the pulse width to 1 milisecond I do see light. I assume this is related to the circuit of the laser 303 and not the diode directly. I am looking for some hack to make this happen.

Thank you
 



Gianakakis

Well-known member
Joined
Apr 27, 2019
Messages
313
Points
63
I am trying to get a 100microsecond long light pulse from a laser 303 pointer. I am generating a square wave input voltage pulse via arduino to drive a mosfet which controls the voltage supply to the laser 303. I do not get any light out of laser 303 with this setup. If I increase the pulse width to 1 milisecond I do see light. I assume this is related to the circuit of the laser 303 and not the diode directly. I am looking for some hack to make this happen.

Thank you
Are you sure you are not increasing the rise/fall time of the square wave instead of the frequency? also, that may very well be because of the capacitors on board the driver. The driver itself is an LM358 based op-amp so it does not have a direct PWM modulation pin in the ic itself. Also if you are doing this with an Arduino try to use the digital write command with a delay function below it instead of PWM.
 

Cyparagon

Well-known member
Joined
Sep 12, 2007
Messages
9,803
Points
113
Short answer is you need to use a different driver to the stock one, because the decoupling capacitance here will eat your pulses and ruin your rise time. A simple dropper resistor might be appropriate if your duty cycle is low.

We can help you a lot better if you actually tell us what you're trying to do, rather then throw us random specification goals with no context.
 

Canozcan

New member
Joined
Jun 29, 2020
Messages
3
Points
1
Hello Again, Thank you for the answers. Let me give you more details. I am trying to mimick what a double pulser laser system do using a laser pointer. I am trying to use the laser for illumination purposes and the laser illumination pulse should be according to the following specification.

Low
100 microsecond high
400 microsecond low
100 microsecond high
Low

This double pulse is will be applied 20Hz to 60Hz according to users input (ie variable). The first pulse is synchronized by another digital signal, coming from the imaging sensor. I created a sketch of the current system below.

I understand that I need to use a different driver or alter the current driver but I do not have any idea how to do that or how to ask from someone do it for me? So any help is appreciated.
Can I order a separate driver? Can I build one from components on a development board? Any clue is appreciated.

Thank you...

Untitled.png
 

Encap

Well-known member
Joined
May 14, 2011
Messages
5,644
Points
113
If the laser 303 is 532nm green it is not direct diode--it is a DPSS laser and you would be much better off with a green or whatever wavelength direct diode laser module, appropriate driver and lens from DTRs's shop instead of trying to do whatever it is with a with a $5 garbage quality laser 303 which you will most likely ruin it if you try take it apart because they are very low cost mass produced press fit and glue assemblies.
If not a 532nm green 303 even then you would still have to take it apart to change the driver ---mostly a waste of time + ruining the host/useable laser pointer.

Have a look at diodes , modules, drivers. and lenses--sold seperately or as complete ready to use assemblies here: https://sites.google.com/site/dtrlpf/
 
Last edited:

Canozcan

New member
Joined
Jun 29, 2020
Messages
3
Points
1
Hello and thank you for the reply. This site has very good products but again I need technical help to select the driver, diode, lens for the technical spec I outlined above. I do not understand which driver/diode combination would give me 100usec pulses, with minimal rise time. Would you have any recommendation on that or can I directly contact this website to get a product recommendation for my needs?

Best Regards...

If the laser 303 is 532nm green it is not direct diode--it is a DPSS laser and you would be much better off with an actual green or whatever wavelength direct diode laser module, appropriate driver and lens from DTRs's shop instead of trying to do whatever it is with a with a $5 garbage quality laser 303 which you will most likely ruin if you try take it apart because they are very low cost mass produced press fit and glue assemblies.
If not a 532nm green 3030 even they you would have to take it apart to change drivers ---mostly a waste of time + ruining the host/useable laser pointer.

See diodes , modules, drivers. and lenses--sold seperately or as complete ready to use assemblies here:
 

Gianakakis

Well-known member
Joined
Apr 27, 2019
Messages
313
Points
63
Hello and thank you for the reply. This site has very good products but again I need technical help to select the driver, diode, lens for the technical spec I outlined above. I do not understand which driver/diode combination would give me 100usec pulses, with minimal rise time. Would you have any recommendation on that or can I directly contact this website to get a product recommendation for my needs?

Best Regards...
This driver has the features you want: https://sites.google.com/site/dtrslasershop/home/laser-drivers/blackbuck-8m-laser-driver-buck
Sadly for not it's out of stock, another driver that might work is the: https://sites.google.com/site/dtrslasershop/home/laser-drivers/super-x-drive-sxd-buck the downside to the second one is that the modulation frequency max is 1khz.
 

Alaskan

Well-known member
LPF Site Supporter
Joined
Jan 29, 2014
Messages
12,478
Points
113
I've never looked into pulsing direct to wavelength laser diodes before, there must be some limit to how short the pulses can be, anyone?
 

Gianakakis

Well-known member
Joined
Apr 27, 2019
Messages
313
Points
63
I've never looked into pulsing direct to wavelength laser diodes before, there must be some limit to how short the pulses can be, anyone?
What really limits the pulses are the caps, In most driver, there is no output enable or PWM pin so you have to switch on and off the entire driver, That leads to the driver's filter caps filtering out your pulses. The driver you would want to use for this is a linear one or a chip with a PWM pin, Then theoretically you are only limited by the driver's max PWM input freq because LDs themselves don't mind pulses. Also adding to this you have to be careful with using high frequencies in linear drivers cause it might in some cases cause them to overshoot on current.
 

Alaskan

Well-known member
LPF Site Supporter
Joined
Jan 29, 2014
Messages
12,478
Points
113
I was just wondering about the diode alone, what happens to the output power as the pulses get shorter and shorter, at some point, I imagine they won't pulse at all, requiring an amount of time to produce output.
 

Mosc007

Active member
Joined
Feb 2, 2012
Messages
572
Points
43
Fibe Optic communication links work in the Ghz range. That gives an idea what the diode itself is capable of.
 

Alaskan

Well-known member
LPF Site Supporter
Joined
Jan 29, 2014
Messages
12,478
Points
113
They are made for it, what about a regular laser diode like we use? I am familiar with fiber optic networks, have worked on them for years.
 




Top