Measuring the wavelength of a diode laser and the birefringence of mica: the experimental examination of the IPHO 40 held in Mexico

Abstract

The experimental examination applied in the 40th International Physics Olympiad held in Merida, Yucatan, Mexico, is presented. The examination consisted of two parts: (1) based on the measurements of a diffraction pattern produced by a diode laser impinging on a sharp edge of a razor blade, the students were asked to estimate the wavelength of the laser. (2) By using the same experimental setup, the contestants had to measure the birefringence of a mica film. For completeness, we give a brief description of the theoretical test. Finally, we present the distribution of marks and show, on the world map, with different colours, the performance of various countries.