Measurement the Thickness of a Thin Film by Automatic and Non-contact

According to the theory of equal thickness interference of white light,we have used the Michelson interferrometer reformed based on MCU to automatically measure the thickness of a transparent thin film,which is a non-contact method.When the angle between the virtual image of the static mirror and the dynamic mirror of the Michelson interferometer is very small,the colored interference fringes will appear.After inserting a thin film,the interference fringes disappear because the optical path difference changed.With rotating of the fine-tuning hand-wheel driven by stepping motor,the thickness of the thin film is measured when the interference fringes appears again.