Powering a Line Laser 5V 200mA using USB port
Well, if you are looking for a quick fix, you can go ahead and plug it into USB. Although a Fuse (200mA) in series with the diode might help. This is good solution only if you are going to use it for very short duration like few hours (continuous use).

But if you want to use it continuously for a very long time like days, this might affect the motherboard of your PC (as the continuous current might lead to heat). If you are using a laptop, there will be side effects on the battery for sure.

So depending on your application, one might or might not suggest you to use a USB as power source.