HIGH-RESOLUTION CONFOCAL MICROSCOPY USING SYNCHROTRON-RADIATION

A confocal scanning light microscope coupled to the Daresbury Synchrot ron Radiation Source is described. The broad spectrum of synchrotron r adiation and the application of achromatic quartz/CaF2 optics allows f or confocal imaging over the wavelength range 200-700 nm. This include s UV light, which is particularly suitable for high-resolution imaging . The results of test measurements using 290-nm light indicate that a lateral resolution better than 100 nm is obtained, An additional advan tage of the white synchrotron radiation is that the excitation wavelen gth can be chosen to match the absorption band of any fluorescent dye, The availability of UV light for confocal microscopy enables studies of naturally occurring fluorophores. The potential applications of the microscope are illustrated by the real-time imaging of hormone traffi c using the naturally occurring oestrogen coumestrol. (The IUPAC name for coumestrol is 9-dihydroxy-6H-benzofuro[3,2-c][1]benzopyran-6-one ( Chem, Abstr, Reg. No. 479-13-0). The trivial name will be used through out this paper.).