Certain types of fluorescent molecules can be exploited in medicine by virtue of the fact that they are retained for longer periods of time in abnormal tissue than in corresponding adjacent normal tissue. Such fluorophores can be used to noninvasively detect the presence, and the boundaries, of abnormal tissue, in a process called photodiagnosis (PD). Many such molecules can also act as photosensitizers, that when excited by light, can cause selective killing to abnormal tissue within which they are located (photodynamic therapy, or PDT). Various devices suitable for application in PD have already been developed, but these devices are expensive, maintenance-intensive, and require extensive user training. The absence of an inexpensive, routine PD device suitable for use in a wide range of applications in the clinics and in doctor's offices is one of the obstacles to wider acceptance of PD and PDT as a routine clinical tool.