Abstract: Apparatus and method are disclosed for encoding information and recording same as sets of variably spaced related marks on the optical record. The encoded information is read by illuminating each set of such recorded marks with a coherent read light to cause an optical interference pattern consisting of a varying distribution of amplitude maxima separated by amplitude nulls (or minimas) that change in accordance with the encoded information. This read interference pattern is detected by photosensing diode arrays and after decoding, the system outputs an information signal representing the original information.