An optical lens system for use in an optical scanning device for scanning an optically scannable record carrier, which lens system comprises a first lens, a second lens, which is relatively small in comparison with the first lens and, in operation, is positioned between the first lens and the record carrier, and a lens holder accommodating the two lenses, characterized in that the lens holder and one of the two lenses are manufactured as one single integrated part from a transparent synthetic material by means of a moulding process, whilst the other lens is arranged in the integrated part as a separate component, with a chamber enclosed by the two lenses and the lens holder communicating with the environment of the lens system via an air vent connection.