A quality-testing apparatus is disclosed for an optical disk of the type that stores optically readable information in the form of a spiral or annular pattern defining a plurality of essentially concentric tracks. The apparatus has a laser light source and a drive mechanism which projects a laser beam spot from the laser light source onto a surface of the optical disk and moves the projected laser beam spot radically over a portion of the disc surface across at least some of the tracks. A light detector detects a reflection from the projected laser beam spot during its movement. The light detector produces a time variant measurement signal (HF) being associated with passages of the moving laser beam spot across respective tracks. A processing device measures the signal amplitude of selected parts of the optical disk and provides an output comprising key parameters such as symmetry and relative signal strength for the annular pattern of pits and lands.