Dimming a laser

[Kakcoo]

I've tried searching google and LPF, but I could not find any good information on this. I'm sorry if this has been answered before. Please provide some better search criterias if you know any.

Is it possible to controll the brightness of a module by using an external potentiometer between the driver and the power source? Would this damage the laser? Would it even work at all? If it workes, I guess that would be a fairly simple way of controlling the color of a multiple color enclosure.

 

[potatorage]

You can turn down the pot on your driver, why would you need an external one?

 

[Kakcoo]

Because the trimpot is supposted to set the upper limit of what power the laser can operate at, and they are not meant for easy adjustment. I want to build a RGV labby enclosure with an easy adjustable color balance.

 

[ElektroFreak]

You could use a second pot in series with the first..

 

[hydrogenman15]

On my RGV labby i use lm317s with fixed resistors and an external pot. Just take the lm317's reference voltage (1.25) and divide it by the max current you want.

Example: You want 420mA's for an open can so 1.25/.420= just under 3 ohms. Its one of the main reasons I like DDL drivers so much.

--Hydro15

 

[nikokapo]

You could use a second pot in series with the first..

This ^

If you use a pot in between the laser & battery you'll encounter major problems if you turn it down too much, the diode will not lase if it's below some given voltage.

 

[Kakcoo]

This ^

If you use a pot in between the laser & battery you'll encounter major problems if you turn it down too much, the diode will not lase if it's below some given voltage.

So pot between laser and battery = nono, but pot in series with pot = gogo?
Can i dim the laser smoothly until it blacks out, or will it stop lasing at some given threashold anyway?

 

[ElektroFreak]

^Yes. Every laser has a threshold below which it will not lase.

 

[Kakcoo]

Aight. But lasing close to this threshold will not damage the diode? (I guess higher resistance will prolong the lifetime)

Edit: I've bought two mirrors for my future first white. I don't know how well these mirrors work for lasers, but they sure are cheap.

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=310043868513
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=310054866112

 

[millirad]

Yep, you want to run the diode at its mean(average) current range, not its peak if you expect it to live for very long. Especially if you want to do an RGV enclosure. Better to build it up once than replace diodes all the time. Let the fog machine do some work.