@dc42 Thanks David.
As a starting point, it seems quite feasible with the clues you provide.
In fact, we were thinking of treating the measurement obtained by the laser as a differential with respect to a known ZMax which is always the same (SMC LESYH16 axes with encoder). With this measurement, we know the distance of the Z axis without the need to create a new type of probe.
But that solves only a part of the possible range. The problem is that we also have to measure the printing tip with respect to that surface and that it also has an offset, so the use of a point laser is not going to solve the problem. We are going to have to think about implementing at least two, one oriented downwards in the Z gantry, and another upwards/sideways to know the distance of the tips. The printheads are interchangeable and several types and shapes.
This is quite complex, and the hardware required is no longer limited to some €470 sensors, but implementing laser profilometers is going to be a major cost apart from software development and RRF.
We will try to do something and see what we can find out. Thank you very much.