It is a multimode laser, so there other lines of intensity within the diode.
By defocusing, you are decombining them. This allows you to see the individual peaks. I hope this helps.
This is an image of a multimode red from Misterwilling from the forum.
No problem
You can see those peaks again, only your images show it more profoundly.
Yes, ever so slightly. The wavelength difference isn't perceivable.
This is one of the reasons single mode diodes are preferable for certain applications.
Your diode and lens are VERY clean, you will also notice some "dots" in the pattern when unfocused also, these will come from dirt and dust on the lens or diode window. Its hard not to get a few at some point.
It is definitely damaged. I have seen damage like this and I bet if you varied the current different lines would light up and go out. You could try different currents and find the current that makes the most uniform pattern. I made a really nice 200mW pen build with a diode that was damaged like this and it ended up having very good divergence. If you have a bench supply you can slowly turn the current up and you will see different lines turning on and off. If you can find a level where it is the most centered and filled out that would be where you could run it for best performance. As for what causes this damage I am not sure but my guess would be a spike or something causing damage to the mirrors in the lasing cavity but not to an extent the diode goes full LED.
