FIELD: optics. SUBSTANCE: objective lens has at least two lens components having Abbe number 40 or more on d-line. At least one of any of its surfaces is aspherical and numerical aperture amounts to 0.7 or more. Optical sensor designed to afford adequate recording and reading of data signals has mentioned lens designed for converging laser beams emitted by light source onto optical recording medium surface to single point. Objective lens of rather large aperture is obtained which enables rather high precision of chromatic aberration correction. EFFECT: facilitated manufacture; enhanced reliability of data signal recording and reading. 8 cl, 109 dwg
