question about beam emitted from dilda

[m60gunner29]

I just got my first lasers in to start experimenting. I have only powered up two of them, both old style dilda and both had what I think is a wierd line pattern. I can focus the beam from a large dot to a small dot but when the dot gets pretty small (the focus point) I can clearly see a line that is going through the dot - so you can see this laser line and the small dot is centered in the line.

This seems kind of wierd to me. Is this an adjustment issue or normal or ?

I tried to take a pic and got a lot of washout from the camera (im not sure how to get nice clean pics of laser dots yet).

 

[daguin]

This is normal for these diodes.

Peace,
dave

 

[sad_sagi]

the "line" comes into focus when the true spot is in focus. i'm not sure why but it does help to focus them. dont be surprised if your DIY red does it too

 

[Milos]

It is an artifact created when diode pattern (which is not circle - see picture below) gets focused (with certain focal length lenses) into a well collimated beam.
There is a technical explanation of this effect , and how the line gets created, but i can't find it now.

-someone might have link.

 

[Deleted member 8382]

My dilda do the same, its not a problem at all

 

[Switch]

It's because the dye (the tiny part emitting the light) is trapped between 2 pieces of something that are really close to eachother and form a thin line between them.The dye is in the middle of this line so the line gets filled with light too.Now the light from the dye is focused by the lens to make the beam and dot, but the image of the line is also focused by the lens and projected on the wall as a line through the dot.

There was a really nice macro picture with good magnification that shown really well how the line was created.But it was in an old thread and I don't even know what to search for.

 

[m60gunner29]

hah!

that is cool




thanks for the info on why that line is there