Eye-safe digital 3-D sensing for space applications

Abstract

This paper focuses on the characteristics and performance of an eye-safe laser range scanner (LARS) with short- and medium-range 3-D sensing capabilities for space applications. This versatile LARS is a precision measurement tool that will complement the current Canadian Space Vision System. The major advantages of the LARS over conventional video-based imaging are its ability to operate with sunlight shining directly into the scanner and its immunity to spurious reflections and shadows, which occur frequently in space. Because the LARS is equipped with two high-speed galvanometers to steer the laser beam, any spatial location within the field of view of the camera can be addressed. This versatility enables the LARS to operate in two basic scan pattern modes: (1) variable-scan-resolution mode and (2) raster-scan mode. In the variable-resolution mode, the LARS can search and track targets and geometrical features on objects located within a field of view of 30 by 30 deg and with corresponding range from about 0.5 to 2000 m. The tracking mode can reach a refresh rate of up to 130 Hz. The raster mode is used primarily for the measurement of registered range and intensity information on large stationary objects. It allows, among other things, target-based measurements, feature-based measurements, and surface-reflectance monitoring. The digitizing and modeling of human subjects, cargo payloads, and environments are also possible with the LARS. Examples illustrating its capabilities are presented.