An apparatus to interrogate, receive, and analyze full emission spectra for at least one fluorescence excitation wavelength and for at least one reflectance measurement to determine tissue characteristics. The apparatus includes a base unit having illumination, detection and control sub-units, the illumination sub-unit providing illumination optical energy for illuminating a target tissue and the detection sub-unit detecting tissue characteristics of a target tissue, a separate tissue interface unit, and a pathway coupling the base unit and the tissue interface unit. The system and apparatus may also include a tube for maintaining the distance between the tissue and units and for surrounding the tissue to prevent patient movement from being transmitted to the tissue.