| An apertureless near-field optical instrument uses any object of subwavelength dimensions to scatter light at a small distance from a surface such that the optical interaction between the object and the surface is local. That local interaction yields subwavelength optical resolution. A reflection-mode apertureless near-field optical microscope (ANSOM) has been developed for microscopy, fluorescence spectroscopy, polarization studies, normal-force studies, and near-field optical studies. Results show that the resolution of near-field optical images can be higher than that of the simultaneous topographical image, with subwavelength optical resolution better than 50 nm. A novel study of polarization contrast was conducted with the ANSOM; distinctive optical images were obtained with different light polarizations. A novel method to remove feedback artifacts from the near-field optical image was developed. Optical and pecking amplitude measurements as the probe tip approaches the sample surface have shown insight into the near-field optical regime as well as normal-force interactions. Preliminary fluorescence spectroscopy has demonstrated that the ANSOM is a promising characterization tool for spectroscopic applications. Design, construction, evaluation, and application of the instrument are described.;A prototype of a commerical ink-jet printing instrument has been developed for the measurement of ink surface position in an orifice of a drop-on-demand printer head as a function of time immediately following the formation of a drop. The development of this instrument involves the design, construction, and calibration of electronic, mechanical, and optical components. The prototype instrument consists of an ink delivery system and device mount, a laser, an optical beam deflection (OBD) system, an optical system for jet-shadow detection, position-sensing detectors with associated electronics, a high sample rate digitizing signal analyzer to record transient signals, and a computer running control software. Real-time ink-jet meniscus oscillations have been measured, providing information concerning the effects of material and dynamic fluid parameters on drop formation under operational conditions. A proposed commercial instrument is described. |
