טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentEvyatar Hemo
SubjectScattering of Singular Beams by Sub Wavelength Objects
DepartmentDepartment of Electrical Engineering
Supervisors Professor Emeritus Shamir Joseph
Dr. Spektor Boris
Full Thesis textFull thesis text - English Version


Abstract

    In recent years there is a constant demand for better methods of measuring nano-scale surfaces, especially in the fields of microelectronics, biomedicine etc. Conventional methods have proven insufficient due to the classical diffraction limit or slow and complicated measuring rate. Therefore, newer methods should be studied. The purpose of this thesis is to study a new sub wavelength objects measuring method, which uses singular light beams. Singular light beams are beams with singular physical characteristics such as singular phase, polarization, etc. Inspection of sub wavelength objects can be done by analyzing scattered singular beams. Therefore, this thesis focuses on the three dimensional interaction between electromagnetic waves and sub wavelength objects.

    At the first stage of the research a scattering simulation software was developed. The simulation is based on Bromwich expansion to the Mie theory. The software was validated by a comparison to analytic results of a plane wave scattering and by simulating Gaussian beams scattered from different materials. The research showed a detector configuration which enable to classify the material of nano particles by analyzing the scattered beams. The second stage of this research included scattering simulations of singular beams from nano particles from different size and materials. The singular beams included the Gauss Laguerre (GL) beam and a "dark" beam which has a narrow dark slit in its center. The scattered fields of the singular beams were studied and several sensor configurations were offered in order to obtain information about the scatterer. The sensor configurations included small sensor at the center of the beam, two adjacent differential sensors and one big sensor. Scattering simulations show improvement at the inspection sensitivity by using "dark" beam. . The differential detector shows even higher SNR improvement using the "dark" beam when semi-dynamic noise is present.