Optical measurements upon compact discs in education in optoelectronics

The aims of this article are connected with application of optical measurement methods in education in electronics. They are used for evaluation of some of peculiarities of different types of compact discs used as optical storage memories. A semiconductor laser diode is used as light beam source during measurements. The compact disc irradiated by laser beam at certain conditions operates as a diffraction grating. By measuring geometrical features of the diffraction patterns and using results from diffraction grating´s theory students can determine the average size of track pitch of different types compact discs (CD-ROM; CD-R: 650 MB, 700 MB, 790 MB, 870 MB, 1300 MB and DVD 4,7 GB). The length of the spiral track is calculated too. Different manners for recording data on compact discs are considered. Comparison between obtained data helps students to understand and clear up peculiarities of different types CDs and possibilities of their applications.