Optical disk technology today finds widespread application in laser vision, compact disk, and data storage equipment. The required specifications of lenses which meet these requirements are discussed. Their image quality is given by rms of wave aberration, by point spread function, by encircled energy, or by modulation transfer function (MTF). Due to the automatic servo focusing technique, a certain amount of field curvature can be tolerated. Measured results of image quality are compared with theoretical values.