Analysis of DVD diffraction patterns under oblique light illumination

Abstract

When an optical disc is illuminated by an incandescent lamp, a bright colored line can be observed on its surface, and the color of the bright line differs with the change of the observer's position. Based on the optical reflection grating structure of DVD, we first establish an optial path model of a source-disc-observer system. Then, we derive analytic equation describing the relationship between the wavelength of the bright lines and the observation angles by applying the scalar diffraction theory. Finally, a simple experimental investigation is carried out and the reliability of the theoretical model is successfully confirmed. This study can be applied to physics experimental teaching in universities, providing a compelling teaching example for students to deeply understand the optical structures and diffraction properties of optical discs.