Lines in defocused spot?

[momo1717]

When at threshold current you can watch the different lasing lines light up as you go up in current. That would be normal but 600mA-1.8A it should be uniform but yours looks like some of them have gone out altogether. What laser driver did you say you were using?

The NDB7875 is a more robust diode for sure but I would rule out a problem with the laser driver before getting another diode. If there is an issue you want to figure that out before connecting another diode to it.:beer:

I was using this driver: 445nm 520nm 1W 2W 3W Laser Diode Drive Driver Board PCB 6-14V Voltage Input - Driver Circuit Board & Power supply - Components and Accessory
I ordered the 1w version and I contacted the manufacturer later on and asked them about the output power for this unit and they said to me that it actually is a 1.2w driver.

 

[CurtisOliver]

I don't know too much about the drivers, but I can suggest in future to look at DTR's ebay posts. He offers diode modules with the appropriate drivers soldered on for you already. If you want to attach the driver on yourself, he also offers you advice on what driver to use. I often buy those with X-drives on them already so I just have to solder on a power adapter. Just supply a appropriate heatsink, and off I go

Here is his post for the M140.
2W 445nm M-Type M140 Blue Laser Diode | eBay

 

[Benm]

A lot of people here are saying the lines are okay, I must disagree. Yes, lines in a multimode diode are normal, but those lines do not look good. That often happens with a damaged diode.

I'd agree on that. It's normal for multimode diodes to have an output pattern with brighter and dimmer bands.

If everything is in proper order these should be mirror-symmetrical around the central line, and not be that pronouced. You can expect a bit of assymetry when just over treshold current, but within normal operating area it should not look like that.