| 摘要 |
PROBLEM TO BE SOLVED: To improve productivity of an optical transmission body having high resolution and to always produce uniform products by forming the transmission body in such a manner that distribution of refractive index at least in a specified region from the center axis of the optical transmission body toward the outer circumference is almost similar to a specified distribution curve of refractive index and the transmission body has specified characteristic values. SOLUTION: This distributed refractive index type optical transmission body has a circular cross section with a radius r0. The distribution of refractive index in the region of 0.25r0 to 0.70r0, preferably 0.20r0 to 0.75r0 from the center toward the outer circumference of the transmission body is almost similar to the distribution curve of refractive index expressed by the formula. The transmission body has characteristic values expressed by 1.4<=n0<=1.6 and 0.3>g>=0.145 mm-1 and characteristics of >=40% MTF(modulation transfer function) measured by using a lattice having 4 line pairs/mm. In the formula, n0 is the refractive index at the center axis of the transmission body, n(r) is the refractive index at the position (r) from the center axis to the outer circumference of the transmission body, (g) is the distribution const. of refractive index and (r) is the distance from the center axis in the direction to the outer circumference of the transmission body. |
