3 ms·

I may be missing something, but when you take 1000 lux and 0.1m², and come up with 100 lumen, the obvious way to put those numbers together is 1000lux × 0.1m² =

I may be missing something, but when you take 1000 lux and 0.1m², and come up with 100 lumen, the obvious way to put those numbers together is 1000lux × 0.1m² = 100 lumen. That's where I got evenly spread over a 30cm square (30 being the square root of 100, to one significant digit). I'm not an expert in the field by any stretch of the imagination, but something seems very wrong with these calculations in that throwing a several-thousand lux image of that size would be easily done with a $500 business projector.

gjm11 15y ago
Yes, I assumed that the light is spread over that area. I didn't assume it's spread evenly over a square of that area. Maybe the shape of the 0.1m² region wasn't important to whatever you had in mind, but then I'm really unsure what your point was since I'd already said I was assuming an area of 0.1m². You can get very bright $500 business projectors. They aren't emitting laser light. If they were, they would have serious problems getting non-scary laser safety classifications. Part of that is because the rules governing laser safety classification are kinda paranoid. Part of it is because coherent light really is specially dangerous. (A 100W light bulb has a luminous efficiency of about 2.5%. A 2.5W laser is really, really, really dangerous.) Anyway, you could do your eyes some serious damage with that $500 business projector. It just happens that there aren't such stringent regulations governing incoherent light sources, because the worst case isn't quite so scary as it is with lasers.