For my undergraduate project, I have been tasked to measure group delay of dielectric mirrors. I have found only papers that point mainly to use a Michelson interferometer using white light interferometry. I have googled and found how to construct a standard Michelson interferometer. However I am having trouble in finding resources on how to modify it to measure group delay. In addition, how can I measure the group delay from the interferogram that is produced from the interferometer? Any books and resources on group delay measurement is highly appreciated.