5 ms·

> the fluid in the human eye is opaque to 1550nm light sure, but does this hold true for most land-based animals and birds? How much range does this give us? r

> the fluid in the human eye is opaque to 1550nm light sure, but does this hold true for most land-based animals and birds? How much range does this give us? reflections can shift by half a wavelength - is that still opaque too? I'm not saying this isn't safe, but suddenly having a tonne of high power laser sources pointing everywhere at all times might actually have some consequences still...

csours 8y ago
Mammals, lizards, amphibians, and birds all have water-based eyes, but I wonder what this would do to insects.
jerf 8y ago
If I am reading the chart labelled "The visible and UV spectra of liquid water" at http://www1.lsbu.ac.uk/water/water_vibrational_spectrum.html http://www1.lsbu.ac.uk/water/water_vibrational_spectrum.html (about 2/3rds down the page) correctly, water is fairly opaque at 1550nm. If my hurried wikipedia education on the topic is correct, that chart is saying it's quite opaque at that frequency, even at bat eyeball scales. Corrections welcomed from people with more training in this field. (I'm not sure I'm not getting some crossed units when I tried to resolve that into numbers normals like me would understand; is that really 1/e^1000 transmitted per centimeter travelled? e^1000 is a big number. There's even bigger ones on that chart. Then again, if a two-atom-thick layer of gold is enough to make something look like gold and completely obscure what's underneath, I guess that might make sense and my intuition is just off, because when I convert that into this sort of scheme I get big numbers there, too.)
- ddebernardy 8y ago
  If memory serves me well, water absorbs that wavelength, so it would basically function sort of like a microwave oven, but with such a much lower energy level that you can basically ignore it.
  - neuralRiot 8y ago
    How will LIDAR work under the rain or snow then?
    - jychang 8y ago
      The same way regular vision works under snow. Snowflakes are opaque to visible light too, so it'd work the same way human eyesight works for drivers currently.
      - paradoxparalax 8y ago
        so maybe we don't need Lidar, because the cameras can see like the human eye in the snow, too. Depth can be given by doing like insects and adding many triangulation points.

csours 8y ago

Mammals, lizards, amphibians, and birds all have water-based eyes, but I wonder what this would do to insects.

jerf 8y ago

If I am reading the chart labelled "The visible and UV spectra of liquid water" at http://www1.lsbu.ac.uk/water/water_vibrational_spectrum.html http://www1.lsbu.ac.uk/water/water_vibrational_spectrum.html (about 2/3rds down the page) correctly, water is fairly opaque at 1550nm. If my hurried wikipedia education on the topic is correct, that chart is saying it's quite opaque at that frequency, even at bat eyeball scales. Corrections welcomed from people with more training in this field. (I'm not sure I'm not getting some crossed units when I tried to resolve that into numbers normals like me would understand; is that really 1/e^1000 transmitted per centimeter travelled? e^1000 is a big number. There's even bigger ones on that chart. Then again, if a two-atom-thick layer of gold is enough to make something look like gold and completely obscure what's underneath, I guess that might make sense and my intuition is just off, because when I convert that into this sort of scheme I get big numbers there, too.)

ddebernardy 8y ago
If memory serves me well, water absorbs that wavelength, so it would basically function sort of like a microwave oven, but with such a much lower energy level that you can basically ignore it.
- neuralRiot 8y ago
  How will LIDAR work under the rain or snow then?
  - jychang 8y ago
    The same way regular vision works under snow. Snowflakes are opaque to visible light too, so it'd work the same way human eyesight works for drivers currently.
    - paradoxparalax 8y ago
      so maybe we don't need Lidar, because the cameras can see like the human eye in the snow, too. Depth can be given by doing like insects and adding many triangulation points.