The purpose of this study is to evaluate a new instrument that shines light and takes digital pictures of skin. The goal is to develop a technique that may enable fast and accurate assessment of surgical margins in the excision of basal cell carcinoma (BCC) or squamous cell carcinoma (SCC). The investigators will evaluate the pictures obtained by the confocal microscope to determine whether this technique may be useful in the future for helping Mohs surgeons remove cancers. In the future, patients may benefit with shorter surgery and improved care.