What's your end goal?  Position/distance sensing?  Data
transmission?  Alignment detection?  Beam breaking
detection?

At any rate, your LED will almost certainly live far beyond
50 mA, if you're pulsing it.  Many LEDs will be quite happy
with short (say, 10 us) pulses above one or two amps.

You might need to be thinking about active amplification
beyond just a pullup.  Your open-collector sensor could
be used to drive another transistor, giving you a good
deal more gain, or an opamp based circuit, or any of a
number of solutions...

Mike H.

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