Telecentric three-dimensional sensor with a liquid mirror for large-object inspection

摘要

We describe a device that applies the advantages of the space invariance oftelecentric triangulation with the measurement of large objects (1 m~(3)). Because the scan motion of the laser beam is decoupled from the physical transport of the sensor head, the fast scanning of large volumes becomes feasible. The device consists of a triangulation laser telemeter head that uses a large liquid primary mirror and an aspheric Secondary mirror to realize the telecentric f-θ objective. We propose using liquid-mirror technology to make low-cost large objectives that have low fnumbers, a diffraction-limited performance, and low scattering in the visible. This new optical system is useful for 3-D measurement. We discuss the optical configuration of the system and the performance of a laboratory prototype. The protctype has a standoff distance of 1.5 m, a telecentric scan as long as 1 m, a depth of view of 1 m, and a relative depth resolution of 0.5-1 mm.