Research Of Super-resolution Radially-polarized-light Pupil-filtering Differential Confocal Microscopy

With the development of nano machining engineering, the elements with nano structure have the property of increasing fine structure and multi-functions.It makes the measurement technology satisfy the high-presion and large-range measurement of nano structure and 3-D in geometrical scale. The property has urgent demands of normalization mass production in nano fabrication. High spatial resolution optical measurement methods and techniques have become a major research topic in modern measurement areas.On the urgent need of high spatial resolution optical measurement, the thesis “Research of radially-polarized-light pupil-filtering differential confocal microscopy” proposes a novel confocal imaging method and technology with higher spatial resolutions and an absolute zero. The technology uses radially polarized-light tight focus and pupil-filtering to improve radial resolution and differential confocal technology to improve axial resolution. The method provide a technology method for high-precision measurements and can widely used in the field of precise manufacturing, metrology and high-precise imaging, and has important theoretic research value and application value.The thesis is supported by the project of National Key Scientific Instrument Development Foundation “Laser differential confocal measurement instrument development and application research”(No.2011YQ040136), the instrument project of National Natural Science Foundation “Development of super resolution differential confocal microscope(No.60927012)”. The following are the main innovative research work I have completed so far:Based on the vector diffraction theory, the theory model and 3-D super-resolution coherent imaging of radially-polarized pupil-filtering differential confocal microscopy imaging by a high N.A. lens is founded, including 3-D transfer function and 3-D point spread function, which serves as the theory and technology foundation of super-resolution radially polarized-light pupil-filtering confocal sensing technology.Based on the genetic algorithm, an optimization model of pupil is set up.The pupil’s parameters such as phase and radius are optimized and designed, and the super-resolution property is discussed. The effect of radial errors and etching errors in pupil’s fabrication on imaging is then analysed.A novel super-resolution radially polarized-light pupil-filtering confocal sensing technology(SRPCST) is proposed, which uses differential confocal technology to improve axial resolution, radially polarized-light tight focus and pupil-filtering to improve radial resolution. In the analysis of pupil parameters and pinhole axial off-sets, optimum axial off-sets of pinhole are calculated and simulated, which provide theory basis for the sensor of radially-polarized-light pupil-filtering differential confocal microscopy.Based on the radially-polarized-light pupil-filtering differential confocal microscopy and the pupil with a higher lateral resolution, a radially-polarized-light pupil-filtering confocal sensor with λ=632.8nm and a radially-polarized-light pupil-filtering differential confocal(SRPDC) sensor with λ=405nm are designed and assembled, and their performances are experimental verificated.Preliminary experiments indicate that with λ=632.8 nm,the lateral resolution can be improved by 15.25% compared with confocal microscopy under the same condition, and with λ=405 nm,the SRPDC sensor lateral resolution can reach 100 nm, axial resolution can reach 1nm, improved by 39% and 3.7 times compared with confocal system, and achieve the super-resolution measurement of fine structure and surface profile.