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Comment by alextousss | Hacker News Reader

I may haven't fully understood your answer, but a typical household mirror could reflect 90% of the laser power in a single coherent direction. Any sufficiently polished metal tool would have dangerous specular direction. I'm not sure of the math for a diffuse reflection, but the laser classification is here for a reason.

A human eye being transparent up to the fragile retina, yes, a laser would penetrate the eye and be concentrated in an extremely small spot on the retina. That's exactly the reason why we have safety around lasers, and why everything above 5mw is strictly for enclosed use. 40 watts shot at random in the void is definitely dangerous by all measures.

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any light reflected in a domestic situation will no longer be a cohearant laser.if it was very focused UV it could cause temporary blindness, but a milisecond pulse will not contain enough energy to burn @ 40 watts, all that said, it is a given that certifying lasers for full on autonomous bug zapping(a dream of billions), is a very steep regulatory hill to climb, and will not be decided on redit, or here but as insectides get less effective while also proving to be realy bad for our environment, and the possibility of a true plauge bieng vectored by mosquitos a constant concern, I am absoulutly certain that research into laser bug zappers is going to progress

Light being coherent and light being dangerous are two completely orthogonal concepts. A laser is dangerous because of the very tight beam, but any household mirror keeps that beam focused. Plus, a mosquito needs 100millijoules to fry (from the intellectual ventures study) which is a lot more than what a retina can handle. The short duration actually makes it even worse, because the eye lids can’t close soon enough to avoid the retina burning (they take 100ms to close). That’s the reason why lasers are classed by power.

A retina being easier to burn than a mosquito is the fundamental reason why we haven’t seen that tech deployed. LiDAR detection with a 2D goniometer + high power laser has been available commercially for a while. There just never was someone to create something so deceptive as to sell a 40watts device as possibly safe.

darn!, but thanks as well alex, I get it, the human eye is ever so perfectly built to bring in and focus light, and I was spitballing based on the fact of laser eye surgery, which must be ever so carefully managed. I hate mosquitos and the rest of the blood sucking vermin that I have to deal with.The work I get up to is horribly dangerous sometimes, so my evaluation of risk and failure modes is not exactly common....nor do I expect it to be, but come on, hey!, laser bug zapers, it's right up there with personal raceing quadracopters, hoverboards, lightsabers, and colonys on mars. I think that people have a reasonable expectation to get wild and crazy stuff, as it is what keeps them paying for all the ever so meticulously engineered stuff that they can care less about. saftey third.

> any light reflected in a domestic situation will no longer be a cohearant laser.

As incorrect as it is misspelled. Reflections are inherently coherent.

> if it was very focused UV it could cause temporary blindness

The wavelength being UV (which it certainly is not) is irrelevant. Blindness can result from any visible spectrum laser, or from thermal IR damage.

You've lost all credibility to me at this point.

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