The eye's sensitivity to brightness *Read*

[Elektrotechniker]

Thanks for this Things. It made my day "brighter"

 

[PlasmaCube]

Also keep in mind that very few things in biology are linear. Twice the output could appear four times as bright, etc.

I was unaware that lasers were biological devices.

XD

 

[ElektroFreak]

Umm... I think he's talking about the eyes. Last time I checked the eyes are biological devices.

 

[Deleted member 8382]

You use lasers to see lasers? :O

 

[Benm]

My favorite way of intuitively understanding this sort of thing is looking at sound intensity.
A sound of 200dB will be incredibly unhealthy, probably fatal.
A sound of 50dB is roughly equal to moderate ambient noise, nothing loud, or even disturbing.

So, if you have four speakers, each playing soft music at 50dB, does that mean that your ears will bleed and you'll die? Of course not!

Well, its interesting, but has little to do with linear perception. The four speakers would yield 56 dB instead of 50 for the single one, but the question is, how much louder does this actually sound?

Most people roughly percieve an increase of 10 dB (or 10 times the power) as a doubling in loudness. So if you want to make someting 16 times louder, you'd need to up the volume by 40 dB, 10.000x the power.

With light this works very differently, since the eye adapts its gain and pupil according to exposure. If you are talking about apparent brightness, its important to consider the conditions you are looking under. In complete darkness, a 10 mW laser would look just as bright as a 100 mW if viewed seperately, because the eye adapts. In a lit room this is not the case, because your eyes will adapt to room brightness are you are able to see the contrast the laser dot makes.

 

[PlasmaCube]

Umm... I think he's talking about the eyes. Last time I checked the eyes are biological devices.

Oh...

My bad.