within a cabinet 34a for the shielding of light with electrical conductors 36a connecting the sensor 28a to the monitor system 22a to transmit light from the laser system 10a to the delivery system 14a the optical interface 24a includes a mirror 30a and a lens system 32a the mirror 30a includes a central aperture which passes light from the laser system 10a to the lens system 32a for transmission through the delivery system 14a to the spot of therapy light is transmitted through the delivery system 14a from the spot of therapy back to the lens system 32a for transmission to the filter 26a the delivery system 14a includes a plurality of light conductors 40a and a light transmission unit 42a connected together so that the light conductors 40a receive light from the lens system 32a originating with the laser system 10a and transmit light from a luminescent surface such as neoplastic tissue containing photosensitive drug back to the lens system 32a for transmission to the filter 26a there may optionally be included other types of equipment such as an endoscope 44a to monitor the therapy the filter 26a is positioned between the mirror 30a and the sensor 28a to pass a narrow band of frequencies to the sensor 29a which converts the light to an electrical signal for transmission through the conductor 36a to the monitor system 22a the mirror is positioned such that light from the delivery system 14a passing.