Easy insert finger sensor for transmission based spectroscopy sensor

A finger sensor system comprising:

• a cylindrical housing configured to be held by a hand of a user, the housing comprising:
• at least one planar surface;
• an exterior curved wall adjacent to the at least one planar surface, the exterior curved wall configured to allow one or more fingers of the user to rest in a natural curved position along the exterior curved wall when the cylindrical housing is held by the hand of the user;
• and
• a finger sensor configured to optically measure one or more physiological parameters from a tissue site on at least one of the one or more fingers resting along the exterior curved wall.