Abstract: The recursion expression applicable to a quarter-wave (QW) multi-layer dielectric film stack with weak absorptions has been used to study the reflection characteristics of mirrors. A weighting factor has been introduced to quantify the contributions of each constituent layer to such mirror characteristics as the reflection delay,reflectivity reduction,etc. For convenience,the weighting factor has been expressed in terms of the refractive indices of the individual layers of the mirror,based on which the reflection delay and reflectivity reduction have been discussed thereafter.