Those are both crude low resolution encoders, the second link appears to be ~80p/rev, which would come out to ~320p/rev after x4 conversion.
a 1200p/rev (before x4) encoder would require a huge diameter wheel using this technique.
In order to make a compact hi-res encoder, it requires a bit of smoke and mirrors called the Moiré effect grating.
A search in the forums will show an explanation.
A 26LS31 can convert to differential line drive for a $1 or so.