| 摘要 |
<p>PROBLEM TO BE SOLVED: To enhance condensing performance with optical loss reduced by a method wherein the boundary between lenses at multilens is formed in such a way that curved surfaces as surfaces of the lenses cross. SOLUTION: A multilens is formed in such a way that principal points S at convex lenses 7, 8, 9 are arranged at equal intervals in the circumferential direction on a triple concentric circle at a light-receiving-element counter face 6 as the inside face of a hemispherical shell body by a polyethylene molded product. The convex lenses 7, 8, 9 are composed respectively of four elements, eight elements and 14 elements. Anglesθ1 ,θ2 ,θ3 which are formed by line segments connecting the principal points S at the convex lenses 7, 8, 9 to a reference point P are set respectively at about 15.3 deg., 31.9 deg. and 46.5 deg. with reference to an axis passing the reference point P in which an infrared detecting element is arranged. The convex lenses 7, 8, 9 have a spherical surface at a radius of curvature of about 6.6mm, and lens thicknesses are set respectively at about 0.6mm, 0.85mm and 1.2mm. The respective lenses are focused on the light receiving face of the infrared detecting element, their areas are made sequentially large in the order of the convex lenses 7, 8, 9, boundaries L between the lenses are formed in such a way that curved surfaces as surfaces of the lenses cross. Consequently, a step part does not exist, the optical loss of a multilens is eliminated due to the step part, and the condensing performance of the multilens is enhanced.</p> |
