Laser scanning gradient index optics microscope: submicrometre scale spectroscopy and imaging at cryogenic temperatures

A laser scanning far-field optical microscope for low-temperature imaging a nd spectroscopy based on gradient index optics is presented, A rod-shaped g radient index microlens is used as a zero-working-distance solid immersion objective lens. The obtained lateral resolution is 310 nm of the FWHM at a wavelength of 545 nm, A laser scanning mechanism located outside an optical cryostat enables one to achieve large scanning ranges independent of tempe rature. The use of the microscope for submicrometre-scale spectroscopy and low-temperature photochemistry performed on molecular J aggregates in thin polymer films is presented.