Novel_Lase_Beam_Steering_Techniques(新型激光束转向技术).doc

Invited Paper Novel Laser Beam Steering Techniques Hans Dieter Tholl Dept. of Optronics Laser Techniques Diehl BGT Defence PO Box 10 11 55, 88641 überlingen, Germany ABSTRACT The paper summarizes laser beam steering techniques for power beaming, sensing, and communication applications. Principles and characteristics of novel mechanical, micro-mechanical and non-mechanical techniques are compiled. Micro-lens based coarse beam steering in combination with liquid crystal or electro-optical phase control for fine steering is presented in more detail. This review addresses beam steering devices which modulate the phase distribution across a laser beam and excludes intra-cavity beam steering, beam steering based on combining tuneable lasers with dispersive optical elements, active optical phased arrays, and optical waveguides. Keywords: Laser beam steering, optical phased arrays, decentered micro-lenses, spatial light modulators 1. INTRODUCTION The integration of laser power beaming, laser-assisted sensing, and laser communication subsystems into autonomous vehicles, airborne and space platforms demands new techniques to steer a laser beam. The new techniques should promote the realization of beam steering devices with large optical apertures which are conformally integrated into the mechanical structure of the platform. The wish list of requirements comprise well-known properties: compact, lightweight, low power, agile, multi-spectral, large field of regard. The angular spread of a laser beam, especially for long range applications, is inherently small because of the high antenna gain of apertures at optical wavelengths. Consequently, the direction of propagation of a laser beam is generally controlled in two steps: (1) A turret with gimballed optical elements points the field-of-view of a transmitting/receiving telescope into the required direction and compensates for platform motions with moderate accuracy and speed. (2) A beam steering device