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I would like to build a setup where I use a light source to emit a signal over a fiber optic cable, and then measure the amount of light that is emitted back, e.g. by blocking/opening the other end of the cable with my thumb. How could I build such a system?

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  • \$\begingroup\$ This is a research question and probably too broad, the first thing you'd need is some optical engineers. My advice would be to use a sensor that measures deflection based on position. \$\endgroup\$ – Voltage Spike Sep 19 '19 at 17:41
  • \$\begingroup\$ I think this kind of devices have been done in the past, it is just that there's really no big markets for them (thus no suppliers). I think I could do it if I somehow first got a proper idea which parts already exist in some form \$\endgroup\$ – mmh Sep 19 '19 at 17:44
  • \$\begingroup\$ hmm, ok, well would it help if we narrow this just to "how to measure back-emitted light from a fiber optic cable"? (or along those lines) \$\endgroup\$ – mmh Sep 19 '19 at 17:48
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    \$\begingroup\$ Maybe look up self-mixing interferometry youtube.com/watch?v=MUdro-6u2Zg Make sure to look in the video description for a link to a paper. You don't need to do self-mixing, but if you don't then you need a bunch of optical components and crystals to split the laser and mix it back onto itself and re-direct it towards an external photodiode. Don't forget laser safety goggles in your budget. \$\endgroup\$ – DKNguyen Sep 19 '19 at 17:52
  • \$\begingroup\$ Thank @DKNguyen, I'll have a look \$\endgroup\$ – mmh Sep 19 '19 at 17:52

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