Even without lasers I don't think that it is a good idea that the sensor is exposed to light all the time if the camera is turned on. With a DSLR you can shoot 1,000 photos with an exposure of 1/200 second each and the sensor will only be exposed for 5 seconds combined. Powering the sensor all the time will warm it up an increase noise and it might also make hot pixels more likely. With my DSLR I even felt bad when I made a short video, because that single video used more sensor time than thousands of photos at daytime.
true, but you're constructing a scenario that isn't real, IMHO.
First of all, if the radiation is strong enough to damage the sensor, it sure as hell would damage your retina looking through the viewfinder. Secondly, good DSLM like my R5 have a proper mechanical shutter that is closed when the camera is shut down, problem solved. The only real advantage is when turned off without lens-cap while looking towards the sun (or a strong (!) laser), the DSLR will just pass most of the energy through the viewfinder and out the back while the shutter curtain of the mirrorless will absorb at least all the visible light (since it's black) and heat up... possibly beyond the point of permanent damage (not sure about the IR reflectance, if they're smart, it's IR reflective).
So there is no damage threshold advantage of the DSLR over the mirrorless while using them. If you are using your camera in situations with lasers >class3, I'd much rather have that laser damage the sensor than my eye!... at least that's my opinion ;-)
1) I do not think that is what is going on here. People are using cameras in places that have lasers.
2) There are remote focus systems that use LIDAR but I have never heard of this happening with them.
1) yes, I get that. Some laser show which is probably running way above legal laser safety specs... otherwise it wouldn't harm a silicon chip
2) the strength of the LIDAR beams is also covered by laser safety regulations. On top of that, the lidar scans as fast as the mechanics and electronics provide, rotating for example. On top of that, the laser dots for LIDAR are usually divergent so they have a certain size. nobody wants super small dots everywhere, it's much more robust if they're larger. Therefore, the intensity is much smaller than with an ordinary laser pointer.
On top of that, a LIDAR usually works in the infrared so that humans won't see the dots/lines... it would drive us all insane otherwise. In the infrared, the optical absorption depth in silicon chips is much longer meaning that the "energy per volume" is smaller in an imaging chip. Also the overall quantum efficiency is smaller meaning less of the infrared photons even cause a signal. More importantly though, almost all camera sensors for RGB (colored) image acquisition have an infrared blocking filter (usually reflecting IR away) so that images look familiar to how we see things. Therefore, an IR laser is unlikely to cause damage to the sensor!! Obviously though the sensors detecting the LIDAR don't have those filters, they might in fact have the opposite, a filter that only lets light of the IR LIDAR wavelength pass so they ONLY see the dots projected and such.
It's the total energy in the light. UV short wavelength light is more energetic than IR. (so violet lasers need more care) For the same apparent brightness, green lasers are safer simply because we see green better so a less powerful laser 'looks' as bright.
first of all you're right, the energy of UV photons is higher than that of IR but that's not the reason the intensity threshold for damaging silicon based imaging chips or photodiodes is much lower in the UV. It's the absorption depth. UV photons get absorbed within <20nm (nanometers) whilst IR photons penetrate hundreds of micrometers or millimeters (depending on the wavelength) into the silicon before being absorbed. Thus, the energy per volume is much higher on the surface of the silicon chip when irradiated with UV.
You're right but also wrong on perceived brightness and deducting danger from that. At the same power, blue/violet and red lasers seems dimmer than green. True UV and IR lasers can't be seen by us directly but you might see some glow from luminescense or fluorescence... something like a black light effect. However IR lasers are even more dangerous than UV ones for the fact that UV lasers primarily won't damage your retina but the cornea or lens. IR lasers usually are more powerful and totally invisible (no fluorescense without special materials).
Bottom line. All visible lasers are a bit safer because people can see them and your eye/iris actually reacts, you blink, shut your eye, look away. Outside the visible spectrum, none of that happens. Then again... if the laser is strong, your reaction time is MUCH too small to prevent damage to your eye, so NO LASER WAVELENGTH is safer than the other if the power is too high ;-)