Tryied pot modding, added 100mA with no change

Hey, so i drilled a hole in my pen were the pot is, i hooked it up to a variable power supply and ran 3 volts at 270mA. i started to turn up the pot and i didnt see any brightness change. i took it all the way up to 380mA (for just a second or two).
what else could be limiting the pump current?

maybe you are saturating the crystals? then adding more current wont do any good accept reducing the diode life...

motorider826 said:

maybe you are saturating the crystals? then adding more current wont do any good accept reducing the diode life...

Click to expand...

Exactly. Not to mention reducing the crystal's life..

Most of the green pens out there(except some of the high-end models) are sorted according to output AFTER production. They, for the most part, have the pump diode set to push the crystal nearly to the max.

Cranking the pot and current only serves to oversturate the crystal(as said) with IR, causing the crystal and possibly the IR pump diode to overheat very quickly, especially in a badly heatsinked pen, with very minimal green power gain. The amount of IR leakage output will most likely skyrocket, though.. not a good thing. This tends to make the power gain look good on a meter, when in reality the main "power gain" is only the added IR leakage.

There are green modules/pens now and again that will give good results from pot-modding, but they are few and far in between.

You have forgotten 1 KEY element!

Our eyes brightness sensitivity isnt linear!!

Once you get to a certain power, it takes ALOT more power for it to appear brighter! My old scanner had a 40mw green module in it. Thinking I wanted a higher power, I got a 100mw CNI module, that does about 141mw. The brightness difference between those was not very big at all!

A good rule of thumb is: 4X the power, for 2X the brightness

Strange stuff, but its true!

Things said:

You have forgotten 1 KEY element!

Our eyes brightness sensitivity isnt linear!!

Once you get to a certain power, it takes ALOT more power for it to appear brighter! My old scanner had a 40mw green module in it. Thinking I wanted a higher power, I got a 100mw CNI module, that does about 141mw. The brightness difference between those was not very big at all!

A good rule of thumb is: 4X the power, for 2X the brightness

Strange stuff, but its true!

Click to expand...

I understand what you are saying, if you are so close to the focused dot then it may be too intense so the eye cannot discern much of a change. But what if I shine it down range at a long distance ware the dot becomes dimmer (on a tree line 1/4 mile away), and then by turning it up I should see an increase in the beam and spot intensity???

Things makes a very valid point. I have noticed this myself. My green has a problem with the switch, and varies in output as the input voltage changes from the switch. I cannot see much difference in the dot itself. I can however see the difference in the beam over long distances.

The fact of the matter is, though, that the crystal in a green laser can only "convert"(short version) so much IR light into green light. What is happening is that your IR pump diode is putting out more IR, yes, but the crystal was most likely putting out as much green as it possibly could before you raised the current. All that is happening now is that there is more IR escaping past the crystal, not to mention the crystal is grossly oversaturated, and will last a much shorter time. You'll probably notice that your laser overheats much faster now. The first sign of an overheated crystal is a change in green output(lower).

EDIT: I reread your original post, and noticed you only turned it up for a second or two. IF you left it there, the above would happen :-/

Bad news, yes, but this is the sad truth.