A light beam encoded with data simultaneously reads out data stored in tracks on an optical disk and produces a reflected beam directed to a detector array. The data stored on the optical disk and the encoded data may be components of vector arrays. As the light beam illuminates the rotating optical disk, the data stored on the disk is multiplied by the encoded data. The products of the multiplication are encoded in the reflected beam. A multiplicity of data is read out in parallel from the optical disk and simultaneously correlated with the encoded data. This comparison or correlation operation is performed on digitally encoded data utilizing convolution, or with analog encoding. The present invention can be utilized in pattern matching.