Multi-dimensional, non-contact metrology using trilateration and high resolution FMCW ladar

Here we propose, describe, and provide experimental proof-of-concept demonstrations of a multidimensional, non-contact-length metrology system design based on high resolution (millimeter to sub-100 micron) frequency modulated continuous wave (FMCW) ladar and trilateration based on length measurements from multiple, optical fiber-connected transmitters. With an accurate FMCW ladar source, the trilateration-based design provides 3D resolution inherently independent of standoff range and allows self-calibration to provide flexible setup of a field system. A proof-of-concept experimental demonstration was performed using a highly stabilized, 2 THz bandwidth chirped laser source, two emitters, and one scanning emitter/receiver providing 1D surface profiles (2D metrology) of diffuse targets. The measured coordinate precision of <200 microns was determined to be limited by laser speckle issues caused by diffuse scattering of the targets.