Experimental evaluation of sensitivity enhancement achieved by heterodyne optical detection in AMCW laser rangefinders for machine vision

Short range laser range finders are a very interesting choice for machine vision and several implementations, oriented to indoor applications have been developed. These systems rely on direct detection, which allows for moderate range and resolution operation, but is a simple, low cost solution. However, some specific applications, such as medium range outdoor operation, may require a higher detection sensitivity that can be achieved by using heterodyne optical detection. In this work, the authors describe an experiment designed to measure the performance enhancement that can be achieved by heterodyne detection (which has been successfully applied to long range laser rangefinders) in an amplitude modulated continuous wave (AMCW) system, better suited to short and medium range operation