A COMPACT FLUORESCENCE AND POLARIZATION NEAR-FIELD SCANNING OPTICAL MICROSCOPE

We present a transmission, fluorescence, and polarization near-field s canning optical microscope with shear-force feedback control that is s mall in size and simple:to operate. This microscope features an ultraf ine mechanical tip/sample approach with continuous manual submicron co ntrol over a range of several millimeters. The piezo-driven 12 mu m x- y scan range is complimented by a 4 mm coarse mechanical translation r ange in each direction. The construction materials used in the mechani cal feedback loop have been carefully chosen for thermal compatibility in order to reduce differential expansion and contraction between the tip and sample. A unique pressure-fit sample mount allows for quick a nd reliable sample exchange. Shear-force feedback light is delivered t o the scan head via an optical fiber so that a remote laser of any typ e may be used as a source. This dither light is collimated and refocus ed onto the tip, delivering a consistently small spot which is collect ed by a high numerical aperture objective. This new scan head incorpor ates an optical system which will permit the linearization of scan pie zo response similar to a scheme used successfully with atomic force mi croscopy. This is designed to both overcome the piezo's inherent hyste resis and to eliminate drift during long duration spatial scans or spe ctroscopic measurements at a single location. The scan head design off ers added flexibility due to the use of optical fibers to deliver the dither and scan Linearization light, and functions in any orientation for use in conjunction with upright or inverted optical microscopes. ( C) 1998 American Institute of Physics. [S0034-6748(98)02707-5]