Abstract: Devices for reflectance spectroscopy, processes of assembling devices for reflectance spectroscopy, and health care processes of using reflectance optical spectroscopy devices are disclosed. The devices include a light source arranged and disposed to apply broadband light to sample, and a light-receiving feature configured to receive reflected light produced by the applying of the broadband light to the sample. The light-receiving feature is arranged and disposed to direct the reflected light to an optical detection system and isolate the reflected light from the broadband light. The optical detection system is capable of differentiating individual frequencies of the reflected light. The processes of assembling include removably positioning the devices on electronic devices. The health care processes include positioning the devices.