What to do with the "case pin" on a laser diode?

[teejammer]

Hello, I'm pretty new to building laser circuits (and relatively new to electronics in general), and I was wondering if anyone can tell me what to do with the "case pin" (third pin that isn't positive or negative) on a laser diode? I've already built 2 circuits, both of which worked (with varying degrees of success), and in both of them, the negative and positive pin on the diode were connected to the driver and the case pin was left unconnected to anything. After watching this video, by styro,

I saw he said to solder the case pin to the negative one. Will I need to do this in future builds? And if not, why was it done in this video?

 

[gazer101]

Some diodes are case polarized (meaning that the diode case itself acts as a massive pin) and the case pin connects to the case. If your diode has both a negative case and separate negative pin (besides the case pin) for instance, you'd need to get a driver that regulates the diodes + input and would only need to wire to the + pin on the diode (the - goes through your laser casing and into the diode since it is case polarized, but the case pin is there in case you want to solder a dedicated - lead to get a better connection if your laser host is not conductive).

Almost all the diodes I buy are not case polarized though, if that's the case just wire to the + and - pins (NOT case pins) as you normally would and you can disregard the case pin

 

[teejammer]

Some diodes are case polarized (meaning that the diode case itself acts as a massive pin) and the case pin connects to the case. If your diode has both a negative case and separate negative pin (besides the case pin) for instance, you'd need to get a driver that regulates the diodes + input and would only need to wire to the + pin on the diode (the - goes through your laser casing and into the diode since it is case polarized, but the case pin is there in case you want to solder a dedicated - lead to get a better connection if your laser host is not conductive).

Almost all the diodes I buy are not case polarized though, if that's the case just wire to the + and - pins (NOT case pins) as you normally would and you can disregard the case pin

Oh ok, I understand. Thanks for the very helpful response!