Laser beam steering - Final report

Non-mechanical laser beam steering using new component technologies is of great interest in several forthcoming military laser systems. Spatial light modulators (SLMs) offer new capabilities to control the laser beam. The SLM consists of a pixelated structure which affects the properties of the incident light. High pointing accuracy, small volume and weight, no mechanical parts, low power consumption and random access pointing are features of this technique. Additional abilities to control the laser beam, such as e.g. multiple beam generation, focusing/defocusing and wavefront corrections, can be obtained. Of particular interest are SLM components based on liquid crystal materials such as ferroelectric liquid crystals (FLC´s). Beam steering can be accomplished by imposing a phase modulation of the wavefront in the form of a phase grating. This report summarises the results in a laser beam steering project where a FLC SLM configuration was used to steer the beam. The main purpose of the project was to study non-mechanical beam steering, identify different military applications, specify technical requirements, characterise and choose suitable LC materials and finally fabricate a 1D beam steerer with corresponding drive electronics. The beam steerer consisted of two 1D SLMs using a high tilt angle FLC material providing low power losses. The two SLMs were cascaded in terms of coherent imaging to obtain four binary phase levels. The beam steerer was preliminarily evaluated and the results are presented in this report.