[time-nuts] Wide angle light into ST connector/multimode fiber?

Hal Murray hmurray at megapathdsl.net
Tue Jan 4 20:04:40 UTC 2011

>  I want to get light from a wide angle (30 degrees or so) into a multimode
> fiber cable to feed a fast MF466 photodiode for short distance sensing.
> That fiber is really small to focus on.  Anyone done this...looking at a
> reflection of a red laser diode  flashing dot a couple of meters away
> through fiber? 

It won't work.  I'm not smart enough to explain the physics.

In addition to the diameter of the fiber, there is also an acceptance angle.

You can probably measure it by shining light into one end of the fiber and 
holding the other end far enough away from a white sheet and measuring the 
spot diameter.

These are my opinions, not necessarily my employer's.  I hate spam.

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