An optical system including at least one optical fiber having a core and cladding, the at least one optical fiber having a cross section defining a circumference, the at least one optical fiber having at least one light scattering discontinuity at least one location therealong, the at least one optical fiber having optical power at least one light transmissive region having a focus located in proximity to the discontinuity, the at least one light scattering discontinuity having an angular extent of less than ten percent of the circumference and the at least one light transmissive region having an angular extent of more than 25% of the circumference and a light source arranged for directing light along the at least one optical fiber.