Abstract: A method of optimising the focus of a fibre laser is described, which comprises positioning the output of a fibre laser relative to a workpiece; measuring at least a portion of back reflected radiation from the workpiece (step 52); determining an integral of this; changing the relative position of the output and the workpiece one or more times (step 54,56), each time determining an integral of values for the back-reflection, and using the integrals to determine optimum focus.

Abstract: An optical assembly comprising a plurality of inputs comprising optical fibres which have a non-circular core cross-section, the fibres having a proximal end for receiving light from a respective diode emitter and a distal end, the fibres being combined at their distal ends and joined to a single output fibre which has a circular core cross-section, whereby in use light from a plurality of diode emitters is combined and output through the single output fibre.

Abstract: A distributor is described for a multi-cylinder laser ignited internal combustion engine. The distributor includes a shaft rotatable by the engine and a plurality of flat reflective surfaces on the shaft. The surfaces lie in planes normal to the axis of rotation of the shaft and are axially staggered from one another along the length of the shaft. An optical transmitter directs light from a laser source to impinge at an angle sequentially on the reflective surfaces as the shaft rotates, and a plurality of optical receivers spaced from one another each receive the light reflected from a respective one of the mirror surfaces and direct the reflected light to a respective one of the engine cylinders.

Abstract: A distributor is described for a multi-cylinder laser ignited internal combustion engine. The distributor includes a shaft rotatable by the engine and a plurality of flat reflective surfaces on the shaft. The surfaces lie in planes normal to the axis of rotation of the shaft and are axially staggered from one another along the length of the shaft. An optical transmitter directs light from a laser source to impinge at an angle sequentially on the reflective surfaces as the shaft rotates, and a plurality of optical receivers spaced from one another each receive the light reflected from a respective one of the mirror surfaces and direct the reflected light to a respective one of the engine cylinders.