quick question.

[joshshermannn1]

does beam diameter affect brightness? for example, would a 200mw green laser with a 2mm beam diameter be less bright than one with a 1mm?

 

[Cyparagon]

Thought experiment: in your experience, what do you think would appear brighter:

100mW laser with a 1mm wide dot
100mW laser with a 10m wide dot

 

[Blord]

The brightness of the beam will be lower if you go from 1mm to 2mm but the total light output will be the same. If you point the laser at the ceiling and you change the focus point, the overall luminance of the room should be the same.