Abstract: ： The ＂half-wave loss＂ phenomenon is directly ning the ＂light and dark＂ inteIfcrence fringes. Based on the shown by changing the interface medium and obtai- deduced distribution equation of interference pattern and the experimental data, we analyze quantitatively this phenomenon according to the calculation of the additional optical path difference produced by reflections on different medium surface. Moreover, the ＂half-wave loss＂ phe- nomenon is illustrated from another point of view by simulating the experimental results in the light of distribution e- quation of interference pattern.

Key words: half-wave loss, experimental research, computer simulation