TWO DIMENSIONAL DIFFRACTION PATTERNS OF He-Ne LASER LIGHT

Abstract

In the course of physics of upper secondary schools, the diffraction and the interference of light are taught. Wave properties,the conditions of interference and so on are studied. A set of a personal computer and a printer can be utilized to make the original figures of many kinds of diffraction gratings. I took the pictures of these figures on minicopy films and made two dimensional diffraction gratings. Fraunhofer diffraction patterns of He-Ne laser light were observed. Students were very interested in the patterns when I showed them in the classes. In this paper,. I report on the observation of Fraunhofer diffraction patterns of He-Ne laser light by two dimensional diffraction gratings: four fundamental lattice arrangements with five kinds of figures(■●▲◆★). By measuring the distances between bright or dark lines of patterns, the lattice constants and the size of figures can be known. This experiment could be a model of X-ray diffraction and electron beam diffraction. In the last section, I show the computer-made diffraction patterns. They are much like the real ones. It will show that physical phenomena can be expressed well by mathematics.