Protecting a laser from voltage drops and ripples

[ozgur84]

Hello everybody,

I have a laser which I want to use in a project. It is cheep and hard to find and the ones in the same class which are easy to find are really expensive and exceed the projects budget. Here is the picture


It is a 3mW laser and the input voltage is 3V. I want to supply the voltage from 2 AAA size 1.5V alkaline batteries.

My first question is: is there a problem if I use the batteries and a switch. (I assume the switching on and off can cause some problems as well as the battery itself)

Second: I think about using a linear voltage regulator and some capacitors to keep the voltage stable but I could not find one which has 3V output voltage but 3.3V.

ok, I will be happy to hear your ideas.

 

[Joe G]

using just 2 batteries won't be enough overhead voltage to use a regulator. We switch laser diodes really fast with no problems on the products we build at my job. but the laser diodes also have current and voltage regulation built into them (its in the housing of the laser diode). I've used the laserdiodes from laser pointers for home projects and had to limit them to under 5volts, but those I couldnt pwm them after a certain fregeuncy, I just ran them from 3 volts (2AA batt). The data sheet should be able to tell you the max. requirements.

 

[ozgur84]

using just 2 batteries won't be enough overhead voltage to use a regulator. We switch laser diodes really fast with no problems on the products we build at my job. but the laser diodes also have current and voltage regulation built into them (its in the housing of the laser diode). I've used the laserdiodes from laser pointers for home projects and had to limit them to under 5volts, but those I couldnt pwm them after a certain fregeuncy, I just ran them from 3 volts (2AA batt). The data sheet should be able to tell you the max. requirements.

Hello Joe G, thanks for your reply and examples. because the laser have to work for a while (let's say around 100 hours) without failing at least until I finish my experiments, I am quite overcautious before I start using it. Unfortunately, I do not have a datasheet or a part number because I bought it from a local shop and they are not able to offer me more information. As I wrote, the ones, which I can actually buy under a brand, are quite expensive, they cost more than 150$.

I think I can use them as you suggested just with a battery and switch. thank you again

 

[Joe G]

Some lasers diodes work better , longer or brighter then others, even the more expensive one's are variable, unless you get those "scientific quality" ones $$$. good luck on your project.

 

[ozgur84]

Some lasers diodes work better , longer or brighter then others, even the more expensive one's are variable, unless you get those "scientific quality" ones $$$. good luck on your project.

Thank you. Scientific grade is quite above the budget for the laser unit for sure One question, I saw some people are using some small capacitors between the leads of a battery for stabilizing the source. do you think this is necessary or what is the reason of using it? (the examples were not for a particular laser related circuit!)

 

[Joe G]

I think it does help w/ the stabilizing of the source voltage, I usually add one for a "reservoir " to all my circuits as a habit, but for using a laser diode as a pointer I haven't.

 

[MikeMl]

Dont you need to regulate the current, (sort of like a LED) and let the voltage take care of itself?

 

[Joe G]

Mike, I'd say yes and no, Depending on the diode being used, the laser diodes we've been using at my job have the current limit built into them, but they have a max Voltage rating of 5volts, I've run them at 15 volts (just messing around with used ones) and the current never went over 36ma. I only ran them for a few minutes though. The ones I've used from pointers I just ran them straight from the 2AA batteries. When using just the laser diode itself, I do use a current limiting circuit feeding it.

 

[MikeMl]

**broken link removed** made for driving Laser Diodes. Read the description of how it works.

 

[Joe G]

nice chip, I saved that datasheet. it got me thinking....

 

[ozgur84]

**broken link removed** made for driving Laser Diodes. Read the description of how it works.

I think this chip is for driving a "laser-diode" but I have a laser source like a laser pointer. but I suppose limiting the current can be useful?

 

[ozgur84]

**broken link removed** made for driving Laser Diodes. Read the description of how it works.

I think this chip is for driving a "laser-diode" but I have a laser source like a laser pointer. but I suppose limiting the current can be useful?

 

[picbits]

A laser pointer generally contains a laser diode. In fact most modern laser devices have a laser diode in.

The laser pointers sometimes have a current regulator in but the cheaper ones from dx.com don't

 

[ozgur84]

A laser pointer generally contains a laser diode. In fact most modern laser devices have a laser diode in.

The laser pointers sometimes have a current regulator in but the cheaper ones from dx.com don't

Could you give some examples of current regulators which I can use with this laser? is it just a resistor? such as 3V/Resistance=XmA..

 

[picbits]

Have a look over on https://laserpointerforums.com/ - it has been discussed to death over there with designs ranging from a simple LM317 regulator to modulated device drivers.

 

[ozgur84]

Have a look over on https://laserpointerforums.com/ - it has been discussed to death over there with designs ranging from a simple LM317 regulator to modulated device drivers.

Thanks a lot! there is a special section for power supplies and drivers great!