Eye-safe imaging and tracking laser scanner system for space applications

This paper discuses the development of a short wavelength infrared laser ranging scanner system at the Canadian Space Agency in cooperation with the National Research Council Canada. A laser source at 1.54 micrometers wavelength is chosen for its relatively eye-safe property. The scanner system is to be considered for use as a space vision system for applications such as robot vision, satellite acquisition and tracking and high resolution 3D imaging for inspection. As an active system, this laser scanner offers an important advantage over conventional vision systems by providing its own illumination and having no dependence on ambient lighting. While providing relatively eye-safe operation, the choice of IR wavelength also improves the background rejection of solar radiation, the latter being about 5.8 times lower than in the visible. The system possesses two modes of operation for making range measurements: triangulation for short distances (0.5 m to 20 m) and time- of-flight for greater range (10 m to beyond 1 km). A short pulse high repetition rate laser is required for time-of- flight measurements. For space applications, the laser must be compact, rugged and efficient while operating in the eye- safe spectrum (1.5 to 1.8 micrometers ). Currently, a YAG laser with an OPO is used to demonstrate the system's operation at 1.54 micrometers , but is too bulky for a space environment. Eventually it will be replaced with a more compact and efficient fiber laser currently being developed. This paper presents the results of the capabilities and performance of the scanner.