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Seems... dangerous? Project states it uses "3mw 780nm Infrared IR Diode Laser". 3mw is enough to damage your eye if you don't blink or turn away. Since it's inf

Seems... dangerous? Project states it uses "3mw 780nm Infrared IR Diode Laser". 3mw is enough to damage your eye if you don't blink or turn away. Since it's infrared, you won't blink, or possible even notice anything (there are no pain receptors in the retina) until it's too late. Wikipedia list "780–1400 nm (near-IR) - Pathological effect: cataract, retinal burn"

yonkshi 9y ago
In the US 5mW is the legal limit for laser pointers. I think that can be used as a guideline, 3mW IR is much less energetic than a 5mW green/blue laser, perhaps it's not powerful enough to cause huge concern? But I agree no amount of laser is safe for the eye. Police LIDAR guns are 905nm at 50mW, that can technically damage you too. https://en.wikipedia.org/wiki/LIDAR_traffic_enforcement#How_it_works https://en.wikipedia.org/wiki/LIDAR_traffic_enforcement#How_...
- vanderZwan 9y ago
  Wouldn't it matter how narrow the laser beam is? 50mW spread out over a larger surface area sounds like it should be safer. Of course, then the question is whether that also comes with an equal reduction in sensitivity, or whether a larger sensor can compensate for that.
- tsukikage 9y ago
  The limit for visible light is as high as it is because of the blink reflex. An IR laser, having a beam you don't perceive as being bright, won't make you blink.
iliasam 9y ago
Laser is rotating fast enough so it is less dangerous. Also laser current is modulated, so laser's average power decreased twice.
- eyeing_see 9y ago
  Which safeguards are implemented to detect that rotation and modulation are taking place as intended?
  - carlmr 9y ago
    I was just going to mention the THERAC 25: https://en.wikipedia.org/wiki/Therac-25 https://en.wikipedia.org/wiki/Therac-25
  - zxcvbn4038 9y ago
    Now that is a question only a true engineer would ask. (If you didn't ask the same question then demote yourself down to "Computer Nerd")
kurthr 9y ago
Well, actually it's near infrared so at this "high" power (3mw) you will definitely see it. You can actually see past 800nm if the source is bright, but I don't recommend it. The wavelength range where optical radiation is visible does not have sharp borders. Here, the wavelength band of 380 nm to 780 nm is used. https://www.icnirp.org/en/frequencies/visible/index.html https://www.icnirp.org/en/frequencies/visible/index.html
dimatura 9y ago
Agreed - I don't enough to say about this particular project, but the lasers in LiDAR sensors do have the potential to be powerful enough to harm eyesight, so I would advise caution. This is not a concern for most commercial sensors, as they are constrained by regulations to a certain power for this same reason. I'm guessing there's no rules for DIY, but it's something to keep in mind if a product came out of this.

yonkshi 9y ago

In the US 5mW is the legal limit for laser pointers. I think that can be used as a guideline, 3mW IR is much less energetic than a 5mW green/blue laser, perhaps it's not powerful enough to cause huge concern? But I agree no amount of laser is safe for the eye. Police LIDAR guns are 905nm at 50mW, that can technically damage you too. https://en.wikipedia.org/wiki/LIDAR_traffic_enforcement#How_it_works https://en.wikipedia.org/wiki/LIDAR_traffic_enforcement#How_...

vanderZwan 9y ago
Wouldn't it matter how narrow the laser beam is? 50mW spread out over a larger surface area sounds like it should be safer. Of course, then the question is whether that also comes with an equal reduction in sensitivity, or whether a larger sensor can compensate for that.
tsukikage 9y ago
The limit for visible light is as high as it is because of the blink reflex. An IR laser, having a beam you don't perceive as being bright, won't make you blink.

iliasam 9y ago

Laser is rotating fast enough so it is less dangerous. Also laser current is modulated, so laser's average power decreased twice.

eyeing_see 9y ago
Which safeguards are implemented to detect that rotation and modulation are taking place as intended?
- carlmr 9y ago
  I was just going to mention the THERAC 25: https://en.wikipedia.org/wiki/Therac-25 https://en.wikipedia.org/wiki/Therac-25
- zxcvbn4038 9y ago
  Now that is a question only a true engineer would ask. (If you didn't ask the same question then demote yourself down to "Computer Nerd")

kurthr 9y ago

Well, actually it's near infrared so at this "high" power (3mw) you will definitely see it. You can actually see past 800nm if the source is bright, but I don't recommend it. The wavelength range where optical radiation is visible does not have sharp borders. Here, the wavelength band of 380 nm to 780 nm is used. https://www.icnirp.org/en/frequencies/visible/index.html https://www.icnirp.org/en/frequencies/visible/index.html

dimatura 9y ago

Agreed - I don't enough to say about this particular project, but the lasers in LiDAR sensors do have the potential to be powerful enough to harm eyesight, so I would advise caution. This is not a concern for most commercial sensors, as they are constrained by regulations to a certain power for this same reason. I'm guessing there's no rules for DIY, but it's something to keep in mind if a product came out of this.