New spectrally resolved confocal scanning laser microscope

We have developed a spectrally resolved confocal microscope with high photon efficiency for photoluminescence and fluorescence measurements. A scanning grating is placed inside the detection arm of the microscope so that the diffraction-limited spot on the sample acts like the entrance slit, and the detector pinhole acts like the exit slit of a standard monochromator. The pinhole also performs the same function as the detector pinhole in a standard confocal microscope. This arrangement has better photon efficiency than focusing the light from the detector pinhole of a standard confocal scanning laser microscope onto the entrance slit of a grating monochromator. This configuration also produces higher spectral resolution and is more flexible than one in which bandpass filters are placed in the detection arm. The microscope is described and measurements of the spectral and axial resolutions are presented. Axial resolution measurements were made using a planar sample that is both reflecting and photoluminescent. Spectrally resolved photoluminescence and fluorescence images are presented.