TRIANGULATION SENSING SYSTEM AND METHOD WITH TRIANGULATION LIGHT EXTENDED FOCUS RANGE USING VARIABLE FOCUS LENS

摘要

A triangulation sensing system includes a projection axis configuration and an imaging axis configuration. The projection axis configuration includes a triangulation light source (e.g. an incoherent source) and a variable focus lens (VFL) that is controlled to rapidly periodically modulate a triangulation light focus position (TLFP) along a Z axis over a focus position scan range, to provide a corresponding triangulation light extended focus range (TLEFR) that supports accurate measurement throughout. In some implementations, the triangulation system may be configured to provide the best measurement accuracy for a workpiece region of interest (WROI) by exposing its triangulation image only when the scanned TLFP temporarily coincides with the WROI Z height. In some implementations, the triangulation system may be configured to limit various measurement operations to using only an operational pixel subset of a detector that receives image light from the WROI, in order to shorten the measurement time.