Laser Diode Problem

[gordonj005]

Hello,
|'ve been using a Hitachi Laser Diode (635 nm, 5 mW HL6335G), and for some reason the beam of the laser has gone from a nice solid band of red, to a more elliptical beam of two bands (a black line down the middle). I tried replacing the diode, but the same thing happened. I've verified that I am well within the operating voltage, but it still does not want to work. Any ideas or suggestions would be much appreciated.

Thanks a lot!

 

[T_Warne]

So, two different diodes exhibit the same beam shape? Weird. Maybe your driver is out of whack? Can you take a picture of the raw beam so we can see what you are describing?

 

[gordonj005]

You're probably right about the driver. This diode has both a laser and a photdiode part of it, and I've noticed that the wire for the photodiode anode has sprung loose, perhaps a part of it.

The shape is a little hard to make out (sorry!), hopefully you can see the two bands.
http://i.imgur.com/IHQex.jpg

Thanks in advance

 

[T_Warne]

What is the orientation of the dark line to the die? Is it perfectly vertical or horizontal? Maybe this is tem01 or tem10?

http://laserpointerforums.com/f44/question-about-tem-laser-modes-69398.html

 

[gordonj005]

It appears to be horizontal, but it doesn't quite match up with the laser modes. The circular shape of the beam is just diffraction, but there are two brighter strips that are separate from the diffraction.