those photosensors are common in every photocopier type machine. Its funny actually how similar the designs are to our machines...
Those steppers are very handy i have a box full of them, the only problem with photocopier ones is they are all custom in terms of current draw, step rate, phase, shaft diameter etc which means you would need to tear apart multiple machines of the same type to get enough.
But you do score sometimes, i managed to get an optical scanner stepper motor from one of our machines that is a high precision 0.6deg step type
ended up hacking the existing driver board with a simple clock driver to control the focus on my telescope
I have to say using the existing boards are great as if you get the wiring diagram you can find all the inputs such as frequency>forward>backward>halfstep A>halfstep B> full stepping>motor lock