1D and 2D laser line scan generation using a fibre optic resonant scanner

Imaging the transverse vibrations of a resonating optical fibre cantilever is shown to be an effective method for generating 1D and 2D laser line scans. The resonant bending modes were excited by mounting a short length of 0.633μm single mode optical fibre on to a commercially available piezo-electric transducer. For an applied sinusoidal driving voltage of 20V pk-pk, the maximum displacement at the free end of an 11mm long fibre cantilever exceeded +/-1.0mm at resonance. The motion at the free end of the fibre was imaged and magnified using a 2mm diameter graded index lens and the resulting flying spot line scan was found to subtend a maximum arc of +/-19°. Two distinct signal detection schemes were implemented and evaluated using standard bar code targets printed on plain paper. 2D Lissajous scans were demonstrated by exciting the orthogonal transverse bending modes of optical fibres with non-circular cross sectional areas. Both D-shaped fibres and circular fibres modified by reactive ion etching were investigated. The principles underlying the design of this Fibre Optic Resonant Scanner (FORS) are directly applicable to the design of an integrated optoelectronic micro-electromechanical scanning device.