fig5 is a schematic illustration of the apparatus as used to perform the spectroscopic luminescence technique previously described in the near field illumination mode the external apparatus illustrated in fig5 are used generally to provide a light source for imaging of the sample and to perform spectroscopic analysis of the optical signal emitted by the sample the external apparatus includes an excitation source 430 an optical microscope 400 a spectrometer 460 and a charge coupled device camera 450 one example of an external excitation source 430 is a continuous wave titanium sapphire laser obtained from the lexel laser corp of palo alto calif light from the excitation source 430 is transmitted to the probe 320 fig4 via an optical fiber 435 up to 2 mw of laser power are used to feed light to the probe from the laser under these conditions an example of an optical microscope 400 is a zeiss axioscope obtained from carl zeiss inc of thornwood n y as illustrated in fig4 the objective if the apparatus is operated in the near field illumination mode transmits a signal 360 through a cryostat window 370 to the external apparatus for analyzing the optical signal as illustrated in fig5 that signal a collimated beam is transmitted through the barrel of an optical microscope 400 the optical microscope is equipped with an eyepiece 410 and a fiber optic coupler 420 the signal is either.