Dave's Mount - 300mW red Mitsu can't get it into focus ?

[hobbybob]

Hi All,

I finally found time to built 2 red modules with 300mW mitsu's.
Have ordered Dave's special mount with the very small lens (already glued in by dave), the 2 mounts and the 2 lenses.

Also have the same set i bought from VJ Ernst, it was already assembled which saved me a lot of time.
When i connect VJ Ernst diode i get a horizontal line on the wall at 7meters distance of about 1 meter wide with 20cm in the middle really lighting up.
Then putting the 2 lenses in front of it i am able to get a nice dot on the wall. The diode is in horizontal with the cut off pin on top.

I put the red diode i bought from VJ Ernst (which come from DTR laser shop) in the same as he did in the set i bought from him.
When i turn this diode on i get a VERTICAL line, but am not able to focus it, with the lens in as deep as Ernst's set i still have a vertical line, or better said block of about 50cm wide. With the lens deeper the vertical line gets smaller and smaller, but then i am in all the way and the lens is almost touching the diode.
Still not in focus. So it seems not deep enough or the diode is sticking in too far. But the other one is perfectly working and is the same set.

I must be doing something wrong but i can't seem to focus a 300mW laserdiode in a Dave special mount ?

Anyone had the same ?
To get it in the same pattern as the set i bought from Ernst i need to rotate the diode 90 degrees so the pins are vertical and then i get a horizontal line......
But again / ofcourse i am still not able to focus it. What i find strange is that i need to put the diode vertical to get a line HORIZONTAL.
The other set i bought from Ernst has the diode horizontal and the line that comes out is also horizontal.
I am going crazy i think.

Hope anyone can help.

Can post pictures later if that helps ?

[kiyoukan]

i have worked alot with the 300mw diodes and pictures would help a ton. also sketches help too.
i have only ever had one 300mw diode that would not focus, but i solved that by decanning the diode.
dont try to decann without the tool.
but why do you need one beam verticle and one horizontal?
i put both so the far patter is a horizontal line and just stack them verticaly.
then send them threw the correction optics.

maybe to much glue on the lens? do you have another lens to try?

[swamidog]

maybe he's combining them with a pbs.

but why do you need one beam verticle and one horizontal?

[kiyoukan]

yea, but then he would not be able to correct one of the beams.
The only way to correct after the pbs is if he used a wave plate.
That way the beams are still the same shape and in the right rotation.

[swamidog]

no. you would correct both beams before the pbs.

yea, but then he would not be able to correct one of the beams.
The only way to correct after the pbs is if he used a wave plate.
That way the beams are still the same shape and in the right rotation.

[hobbybob]

Sorry, i wasn't clear enough. i want to built 2 separate modules. So i am not combining one with the other.
But i used the one i bought of Ernst as an example. When i built it the same i was expecting the same end-result. But it didn't.

I will post some pictures to clarify.

[tonyaztec]

Hi Dimitri,

The centre pin on the diode needs to be centre top, to give a horizontal stripe, it will not work 90 degrees round, I did have a similar issue some time ago where I could not get focus, turns out that what I had done was to wind the 2mm lens in to close to the diode and the it cracked the glass on the diode itself, a lot easier to do than you may think.

Just have a look to make sure this has not happened.

Any pics please?

Tony

[hobbybob]

Ok i have made some pictures to explain what is going wrong and what i don't understand.

Here you see the already soldered unit i bought from Ernst.
For all the photo's tilt your head to the left. Else i have to rewrite all the text below ;-)
Take a good look and see the positive lead is on the left. GND is on the right. Cut of pin is on top.


Then the one i made. Positive on the left, GND on the right , cut of pin is on the top.
So exactly the same as i bought.


This is the focussed but uncorrected beam from the module from Ernst.


Another shot of uncorrected beam


Now corrected:


This is how i set up the corrective lenses on the ernst module.


Then my beam uncorrected, cannot turn the lens in further!


Now corrected with the lenses.


And again, how i set it up.


So i completely copied the setup of Ernst, yet my beam comes out vertical and his one is horizontal.
Ofcourse i can turn/rotate the diode, that's no problem.
But my focussing problem remains. How come i cannot focus this diode ?
And why is the beam vertical when the other one is horizontal ?

@Tony I carefully turned the lens in by hand/finger and stopped when i would go further.
Took out diode, still looked ok, no crack. Still could not get it to focus correctly.

Hope the pictures clear up things any help is appreciated.

[tonyaztec]

I will experiment with one I'm building now to see if I can replicate you stripe, only thing about setting the diode lens is that the tinyist of turn when it is close to being set can make a massive difference, did you set the diode lens with no corrective lenses in place first?

[hobbybob]

My method is normally:

Set the focus of the lens (without any corrective optics and shit)
place corrective optics
Done

But setting the focus is where the problem is, i can't seem to set the focus on this one, i cannot get it any deeper in (or i'll damage the lens or crack the diode).