How to keep light out with passive air intake in cab or closet

OK, I now I am a newbie, and some of my questions may seem dull, however these are things I need to know, so I appreciate your help.

So if a person is going to have passive air intakes in the cab or closet, meaning a few 4 inch holes on the bottom of the grow area, how do you keep the light from outside the grow area from entering the grow area? I know there is a way to do so, because I read about people using passive intakes, I just can't find anything that mentions how they keep the light out.

Any thougths?

Thank you

A light baffle of sorts... You'll need to use your ingenuity to adapt the principal to your specific grow area.

also if youre in a small area like a cab/closet you'll not need a few 4" intakes, probably just 1

I am considering using a small piece of duct with a bend in it, probably going up. This way I do not believe the light would get in, because I don't think light will bend. Not sure I will have to do a test. What do others do to keep the light out? How do you build your light baffles? To be honest other than my idea of using ducting, I really have no ideas how to keep the light out of a passive air intake.

Spray the inside flat black. Light doesn't bend, but it will reflect. A flat black surface will not reflect any light

thanks Jack