Jin Seung Kim

Polarimetric Measurement of Jones Matrix of a Twisted Nematic Liquid Crystal Spatial Light Modulator

A polarimetric experimental method was developed to determine the Jones matrix elements of transparent optical materials without sign ambiguity. A set of polarization dependent transmittance data of the samples was measured with polarizer - sample - analyzer system and another set of data was measured with polarizer - sample - quarter-wave plate - analyzer. Two data sets were compared and mathematically analyzed to obtain the correct signs of the elements of the matrix. The Jones matrix elements of a quarter-wave plate were determined to check the validity of the method. The experimentally obtained matrix elements of the quarter-wave plate were consistent with the theoretical expectations. The same method was applied to obtain the Jones matrix elements of a twisted nematic liquid crystal panel.

General Theory of Wave Scattering by Two Separated Particles

A general theory of scalar wave scattering by two separated particles is developed to give the coefficients of scattering and transmission in the form of recurrence formulae. Iterative applications of the formulae yield the coefficients in the form of power series of the coefficients obtained from single-particle scattering theories, and each term of the of power series can be interpreted as multiple scattering of the wave between the two particles in increasingly higher order.

Scattering of a Normally Incident Monochromatic Light by Optically Active Concentric Double Cylinders: II. Numerical Result

The scattering of a normally incident monochromatic light by optically active concentric double cylinders is studied by using a numerical method. A numerical code is developed on the basis of the analytical solutions, and the angular distributions of the intensity and the polarization of the scattered light are computed for some specific cases. The numerical code can be used to non-invasively determine the size, structure, and composition of a double cylinder with high accuracy by measuring the angular distribution of the scattered light by an experiment.Keywords: Optically active concentric cylinders, Light scatteringOCIS codes: (240.3695) Linear and nonlinear light scattering from surfaces; (160.1585) Chiral media

Revised Algorithm for Image Sharpness Measurement in Scanning Electron Microscopy Based on Derivative Method in ISO/TS 24597 Document

First, the data length of the edge directional lines for fit to the error function should be adaptively controlled to maintain the fitting accuracy. Otherwise, different image magnification results in different sharpness, that is, higher magnification may estimate better sharpness than lower magnification. We updated WISE-FDL (fixed data length) to WISE-VDL(variable data length) to resolve this, which uses the data length varying according to the image sharpness (Figure 1). The magnification of the image is recommended to be large enough so that the adjacent pixels do not overlap each other.

Room temperature optical anisotropy of a LaMnO3 thin-film induced by ultra-short pulse laser

We observed ultra-short laser pulse-induced transient optical anisotropy in a LaMnO3 thin film. The anisotropy was induced by laser pulse irradiation with a fluence of less than 0.1 mJ/cm2 at room temperature. The transmittance and reflectance showed strong dependence on the polarization states of the pulses. For parallel and perpendicular polarization states, there exists a difference of approximately 0.2% for transmittance and 0.05% for reflectance at 0.3 ps after the irradiation with a pump pulse, respectively. The theoretical values for optical transmittance and reflectance with an assumption of an orbital ordering of 3d eg electrons in Mn3+ ions showed good agreement with the experimental results, demonstrating that the transient optical anisotropy in LaMnO3 thin film is due to the photo-induced symmetry-breaking of orbital ordering in excited states.

Cross-sectional atomic force microscope in scanning electron microscope

A newly designed atomic force microscope (referred to as “cross-sectional AFM” or “xAFM”) is demonstrated that enables tip–sample interactions to be studied directly from a cross-sectional scanning electron microscope (SEM) view during AFM operation. Previously, such interactions have only been modeled using computer simulations or sensor-generating data. The xAFM will allow researchers to acquire additional visual information not available with conventional microscopic techniques. The xAFM is operated in a tungsten filament SEM, by examining a grating sample that is cleaved and mounted on the sample scanner so that the cleaved cross section faces upwards toward the bottom of the electron column. The tip scans horizontally, parallel to and at a height slightly lower than the cross-sectional surface of the sample but within the depth of focus of the SEM. Three experiments are described that show the unique features of the xAFM. The first demonstrates direct observation of the “tip-convolution” in real-time SEM images. The second shows unambiguous identification of an artifact in the lateral force microscope, from which a “double dip” appears in the signal from a damaged tip in a backward scan of the grating surface. The third enables measurements from blurred SEM images of large-amplitude oscillating high-Q AFM cantilevers in vacuum.

Phase change measurement of birefringent optical devices with white light interferometry

This paper describes a method to determine the phase retardation of birefringent optical components by combining spectral interferometry and the Fourier transform method. The retardation of each orthogonal polarization component was resolved by using two rotatable linear polarizers in the interferometer. The phase retardation measured by using suggested method was compared to that measured using the conventional polarimetric method. The results of independent methods were well matched, which confirms the validity of the proposed method.

A photopolarimeter for real-time analysis of dynamic characteristics of LC cells

For the development of large area or high resolution LCD (liquid crystal display) devices, it is necessary to have a proper understanding of the dynamic characteristics of LC cells, for which measurement of time-dependent transmission properties of LC cells is needed. In this paper, we present a real-time photo-polarimeter based on non-polarizing beam splitters for measuring the dynamic evolution of the state of polarization of the light passing through an LC cell.