Stability Research of Laser Confocal Probe for Measuring the Micro-Shpere

Abstract

Laser confocal probe, on an active focus adjusting principle, was introduced in this paper. This kind of non-contact laser probe has the abilities to do the detection on strong reflection of the surface of high precision metal parts and optical devices. So, a problem of shape inspection detection was resolved. The micro-sphere is the key element in the ICF (short for inertial confinement fusion) system. The success or failure of "Ignition" is directly related to the accuracy of the assembly location of micro-sphere in the micro-target. Because of the particularity of the micro-sphere, laser confocal probe is used to do the detection of the center error of micro-sphere. The required measurement precision is less than 3µm. The mathematical formula between the height defference or the displacement value of measured surface and the displacement valued of the tuning fork can be gotten by the time different principle. Good stability of frequency and the swing of tuning fork, which approved through the experiments, have little influence to the time different Δt and the final measurement results.