Abstract: A method and an apparatus are proposed for performing a comparison of patterns of invariable form, especially fingerprint pattern. By the application of a finger on a prism within a beam of light, a latent picture of fingerprint lines is obtained which is optically compared with a copy of the same fingerprint stored in memory or located on a card. After conversion into an electrical variable, an identification pulse results which is subjected to at least one test criterion and compared with a threshold value. Preferably the testing of a master symbol located on the inserted card is effected at the same time, comparing this with a copy of the same stored in memory within the appliance. If the test criteria show an agreement of the fingerprint with the fingerprint copy and/or of the master symbol with the copy of the master symbol then a positive assessment is effected, and access to a building, for instance, is furnished.