There are 2 PNP output, light-on (used for the led's) and also dark-on, which trigger probe input. The object to control the lightbeam looks like this, the small diameter is machined 0.25 - 0.3mm. Years ago i did some testing about this, and this design worked well for me.
I clamp the probe in oriented position, but it needs compensation. My probing routines can handle multiple probes 4, quadrants error compensated. I use the toolnumber for the compensation file, eg T999, to call the compensation parameter, 'o#5400 call' does read 999.ngc and loads global variables for this probe. Then the results are repeated within 0.02mm