CAREER: Near-field optical tomography

University Of Illinois At Urbana-Champaign, Urbana IL

Investigators

Abstract

0239265 Carney Near-field optical tomography is placed at the nexus of two fields: near-field optics and inverse scattering. Near-field imaging has attracted considerable attention as a technique to obtain images of surfaces with subwavelength resolution. Applications range from the inspection of organic and biological samples to semiconductor devices. Various experimental modalities are in practical use. Near-field scanning optical microscopy (NSOM) is practiced in many variations. Total internal reflection microscopy (TIRM) has been in practical use for decades. At the intersection of NSOM and TIRM modalities are the so-called photon scanning tunneling microscopy (PSTM) methods. In all of these modalities, the connection between the measured field or signal and the sample properties has proven to be problematic. To clarify the meaning of the measurements and to provide three-dimensional imaging capability, it is desirable to find a solution to the inverse scattering problem (ISP). By solving the near-field ISP two issues are resolved. The ambiguity in the relationship between the sample properties and the measured data is removed, and simultaneously three-dimensional, tomographic images of the sample are obtained. Significant progress in this area has already been made by the PI and collaborators. The feasibility of near-field tomographic reconstructions has been demonstrated within the framework of a scalar model. Moreover, new a modality, near-field optical power extinction tomography (NOPET), has been proposed to circumvent the phase problem inherent in the ISP. The aims of the research program are: 1) To develop inverse scattering algorithms for all of the modalities discussed above in the weak scattering limit; 2) To apply the algorithms to experiment; 3) To develop inverse scattering algorithms in the strong scattering regime; 4) To apply the strong scattering algorithms to experiment; 5) To include the results of research in the graduate curriculum of the Department. The PI has outlined specific methods, a timeline, and assignment of personnel to achieve these aims. He has a proven record of accomplishment in the field of research, is an experienced educator and is committed to diversity in the classroom and in his group. The research will translate directly to the classroom. Furthermore, graduate students will be trained in the course of this work and undergraduates will be included wherever possible. Results will be disseminated through the literature and conferences. The results of this work will have broad impact. The intellectual impact of the project is significant in that it opens a new field of study. The novel methods of microscopy developed will impact biology, material science, semiconductor research and manufacture, optoelectronics, chemistry, and medicine. This work will also result in a deepening of our understanding of the behavior of light on very small scale and will have applications beyond imaging in photonics and optoelectronics. The program of research described here will provide students in the research group with a broad range of research experience from fundamental physics to code development and applied engineering. Students outside the group will benefit from the integration of research results into graduate coursework. In the long term, the effect of student training will affect the future development of microscopy. This work will form the basis for a career in academic engineering. The PI will contribute to the body of knowledge, educate in the classroom, and foster the development of young researchers for years to come.