PRODUCTION FOR ELLIPTICALLY DISTRIBUTED INDEX LENS

PURPOSE:To use high polymer materials and to produce easily an elliptically distributed index lens by changing the quantity of light irradiated to the circumferential face of a columnar optical medium to a sine wave shape in the circumferential direction so that two periods of sine wave exists on the overall circumference. CONSTITUTION:A vessel 11 containing an optical medium 10 is rotated on a turntable 12 to irradiate the circumferential face of the vessel 11 with an ultraviolet parallel light through a mirror 21. If the light transmission quantity of the sine wave is controlled by an optical modulator 20 so that two periods of sine wave coincide with one rotation of the turntable 12, the quantity of light is maximum at points B and D and minimum at points A and C, and the refractive index distribution in the radial direction of the optical medium 10 is a square-law curve, and the curve is sharp in the section passing points B and D and is slow in the section passing points A and C. Consequently, an equal refractive index curve En on the cross section of the converged optical beam is elliptic, and an optical beam S3 formed to a complete circle is obtained.