Abstract: The thickness of saponaceous-films is measured by using a Michelson interferometer with the white- light used for interference. Detailed study has been made for the influence of the number of layers of the films used on the interference pattern obtained, and the influence of the distinguishability of the zero-order interference stripe on the film thickness measured. With the widths of the interference stripes kept constant, measurements obtained with varies numbers of saponaceous-film layers are compared ; Meanuhile, comparison of the measurements obtained with a constant number of layer but different widths of interference stripes are also carried out. The thickness at the centre of the films are calculated based on the data obtained, and the mechanisms causing the uncertainty of meas- urements in different measurement conditions are comparatively analyzed. In results, monolayer and double layers of saponaceous-films are more suitable for the measurement with relatively wider interference stripes. In contrast, a four-layer film system suits more for that using more narrow interference stripes.

Key words: white-light interference, Michelson interferometer, thickness of saponaceous-film, width of inter-ference stripes, comparative analysis