PURPOSE: To diffuse effectively the light transmitted within a columnar photoconductor, by forming a conical part to the photoconductor to diffuse the light and then discharging the light after converting it into various types of illumination beams.

CONSTITUTION: A light radiator 1 consists of a columnar photoconductor part 1a and a tapered and trapezoidal conical photoconductor part 1b. Then the focused sunbeam travels while reflected by the wall surface and is discharged through an end face B with a considerable degree of diffusion while it is reflected by the wall surface of the part 1b. In the case of the input focused light L2, the discharged light has a raindbow striped pattern and is not suited to the ordinary illumination. This discharged light, however, can be used effectively for decorative purpose. If parallel beams L1 are delivered to the face A, the light having nearly the same property as that of the delivered beams is discharged through the face B of the conductor 1.