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I'm using the Vl6180 time of flight sensor to measure a distance to a surface.

This surface is a liquid, water for example. In my setup, the sensor doesn't detect the surface, the pulses from the laser goes right through. It seems there is not enough reflection at the surface.

Putting something on the surface that will reflect is not a solution in my case.

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  • \$\begingroup\$ Are you wedded to using this particular sensor given the issues with detection? An ultrasonic sensor could be a cheap alternative see circuitstoday.com/…. for an example idea \$\endgroup\$
    – mhaselup
    Sep 16, 2020 at 2:48

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If you cannot put a dye in the liquid the only alternative I can think of is to make sure the beam from the chip hits the surface of the liquid at an angle that will guarantee some reflection. In order to recover the reflected beam you would also need to factor in a mirror to return the reflected beam to the chip.

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  • \$\begingroup\$ Maybe the dye could work, only the dye should be compatible with an IR laser. \$\endgroup\$ Sep 14, 2020 at 10:20
  • \$\begingroup\$ @paulusvanderEnd Almost any dye would be suitable since it is very near IR. You could try en.wikipedia.org/wiki/Rhodamine_B \$\endgroup\$ Sep 14, 2020 at 13:16
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Generally, TOF laser distance sensors are not suitable for measuring distances to anything transparent at the laser's wavelength.

Bouncing the laser beam at an angle may work, but the problem then is getting the bounced laser light back to the sensor, and doing the math to get the actual distance.

Strangely, success has been reported with a specific sensor, but I don't know how reproducible it will prove to be; I haven't tried.

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