Abstract: A method and apparatus for embossing diffraction gratings on a record medium is disclosed. The diffraction gratings are embossed on a strip of aluminized plastic which is later imbedded in a record medium like a "credit card" for use in a security system which utilizes data recorded in the form of diffraction gratings and data recorded in magnetic stripes on the card. The apparatus utilizes embossing masters in the form of "type bars" or grating bars which are selectively indexed to an embossing station where the embossing takes place under controlled heat and pressure conditions. A special method or layout scheme is used in laying out the embossing masters on the grating bars.