Learnt something today about red diodes

[andy_con]

for the past two days ive been dicking around with my quad red -



i was getting annoyed with the beams being weird, they were out of focus and not aligned. i would refocus them and re align not even move the projector come back 30mins later and they were all off again.

so i started working through each part to find the problem.

after two days it turns out there was actually nothing wrong at all. when the diodes are cold you get a big blob -



as soon as you leave them to warm up for 5-10mins that blob turns into a dot.

so interesting...

these are the open can 660 diodes

[shrad]

If I didn't see the teflon tape, I'd have said that the spring used to load the collimating lenses was dilating in a rotary movement, which would have moved the focus (and hopefully set it back during contraction because of the sharpness of the last turn of the spring)

but there, I could only say there is some dilatation going on to the diode-housing interface

strange

[andy_con]

there are no springs in the aixiz housing so they wernt causing the problem

[krazer]

How cold do you mean by cold? Its possible you had some condensation which would cause the effect you are seeing.

[andy_con]

not ice cold, i just mean turning the projector on for the first time cold. like a green module warming up

[jaycey]

Thanks for the info Andy, I have been experiencing the same problem with my dual build.

Focus it and then finding it going out of focus was driving me mad...now I know why!


Cheers

[mccarrot]

Do you also have this problem without the telescope.

I could be due to thermal stability of your mechanics. (alluminium get warmer and extends making the distance between the 2 lenses bigger)

[flecom]

laserwave was having the same problem with their higher powered 642nm modules

I have a 500mW 642nm laserwave (never released) and it does something very similar so it might affect the 150mW 642 diodes also

the construction of the laserwaves is very similar to what you did too including the telescope

[andy_con]

Do you also have this problem without the telescope.

I could be due to thermal stability of your mechanics. (alluminium get warmer and extends making the distance between the 2 lenses bigger)

not tried without the telescopics.

it could be that but i dont think it is, when i say warms up its not like warm warm.

i could be completely wrong but i think its something to do with the actual diodes warming up

flecom

laserwave was having the same problem with their higher powered 642nm modules

I have a 500mW 642nm laserwave (never released) and it does something very similar so it might affect the 150mW 642 diodes also

the construction of the laserwaves is very similar to what you did too including the telescope

really didnt know that

[MisterWilling]

Maybe it has something to do with the insulator you use around the aixiz modules. I'm sure that it expands and contracts more than aluminum does, so that might be changing the exit path of the laser causing them to be out of alignment. Just throwing a guess out there though.

Maybe you should block out three of the four diodes with an object and watch what happens to the output of the single diode during warmup (outside size, shape, and location).