OPTICAL TRANSMISSION BODY, OPTICAL TRANSMISSION BODY ARRAY AND IMAGE SENSOR

摘要

PROBLEM TO BE SOLVED: To provide an optical transmission body having a large lens diameter, a short conjugate length and a deep depth of focus. SOLUTION: This is a cylindrical optical transmission body 1 having a distribution approximated by a quadratic curve in which a radius r is 0.2 mm-0.45 mm and at least a refractive index distribution at 0.3r-0.7r from a center axis 4 is stipulated by n (L) =n0 1-(g2/2)L2} (provided that, n0 is a refractive index in the center axis of an optical transmission body, L is a distance (0<=L<=r) from the center axis of the optical transmission body; g is a refractive index distribution constant of the optical transmission body and n (L) is a refractive index at the position to a distance L from the center axis of the optical transmission body). The constant g satisfies 0.35 mm-1<=g<=0.5 mm-1 and 0.10<=g.r<=0.16 at a wave length of 570 nm. A photo-absorbent coexistence layer 2 having 50μm or more thickness is formed in the region within 100μm range from the outer circumference toward the center axis, within the range of 0.6r or more outside from the center axis and including the range of 0.8r-0.95r.