* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Concepts for the simulation of volume and surface scattering based
Phase-contrast X-ray imaging wikipedia , lookup
Ray tracing (graphics) wikipedia , lookup
Reflection high-energy electron diffraction wikipedia , lookup
X-ray fluorescence wikipedia , lookup
Optical coherence tomography wikipedia , lookup
Vibrational analysis with scanning probe microscopy wikipedia , lookup
Magnetic circular dichroism wikipedia , lookup
Ultraviolet–visible spectroscopy wikipedia , lookup
Photon scanning microscopy wikipedia , lookup
Optical tweezers wikipedia , lookup
Nonlinear optics wikipedia , lookup
Nonimaging optics wikipedia , lookup
Optical flat wikipedia , lookup
Thomas Young (scientist) wikipedia , lookup
Anti-reflective coating wikipedia , lookup
Harold Hopkins (physicist) wikipedia , lookup
Surface plasmon resonance microscopy wikipedia , lookup
Atmospheric optics wikipedia , lookup
Retroreflector wikipedia , lookup
Transparency and translucency wikipedia , lookup
Low-energy electron diffraction wikipedia , lookup
Concepts for the simulation of volume and surface scattering based on field tracing Dr. Michael Kuhn Dr. Hagen Schweitzer LightTrans VirtualLab UG Introduction Introduction • Presentation will show concepts for physical optics modeling of scattering effects. • Discussion of: – Surface scattering – Volume scattering Surface Scattering • Surface scattering caused by: – Roughness – Scratches – Fabrication tolerances • Roughness statistical variation Surface Scattering Rough surface of plate. Surface Scattering • Surface scattering caused by: – Roughness – Scratches – Fabrication tolerances • Roughness statistical variation • Scratches and fabrication tolerances often regular variations of the surface. Surface Scattering Surface deviation of aspherical lens manufactured by CNC technic. Regular surface deviations are visible. Volume Scattering • There exists several different scattering effects. • Scattering caused by particles, schlieres/reams, mechanical stress. • Size of scattering structures ranges from atomic size to large extensions. • We will discuss scattering at volume structures with dimension of several 10 nm to Millimeters. • Scattering models have to include diffraction and interference effects. Volume Scattering Spherical particles Modeling Modeling of Scattering • Measurement of intensity of scattered light distribution and usage of measured data for simulations: No phase and coherence information. Can’t be used for accurate physical optics modeling. • Analytical models for surface and volume scattering: Modeling of specific scattering setups only. No general solution. • Numerical simulation of scattering required! Modeling of Scattering: System Light Source Detector Modeling of Scattering: Sources Increasing number of different types of light sources ranging from: • • • • • Spatially coherent to incoherent Unpolarized to polarized Cw/stationary to fs pulses Small to large bandwidth X-ray to IR Light representation • Electromagnetic f ield representation required. Modeling of Scattering: Detectors Innovative optical design often requires accurate access (merit function) to e.g. • • • • • Amplitude and phase Polarization, e.g. Stokes or Jones vector Degree of polarization and coherence Poynting vector, energy flow Pulse duration, chirp, … Light representation • Electromagnetic f ield representation required. Modeling of Scattering: Structures • Enormous variety of different types of optical surfaces: – Smooth freeform surfaces Modeling of Scattering: Structures • Enormous variety of different types of optical surfaces: – Smooth freeform surfaces – Microstructured surfaces Modeling of Scattering: Structures • Enormous variety of different types of optical surfaces: – Smooth freeform surfaces – Microstructured surfaces – Multilevel surfaces Modeling of Scattering: Structures • Enormous variety of different types of optical surfaces: – – – – Smooth freeform surfaces Microstructured surfaces Multilevel surfaces Miniaturized components • Surfaces with different feature sizes are combined in optical systems. • One modeling technique for all of that? Modeling of Scattering: Propagation Light Source Detector Ray tracing? Rigorous System Modeling Light Source (FEM, FTDT,..…) Detector Rigorous electromagnetic solution of Maxwell‘s equations? Modeling of Scattering: Propagation Light Source Detector Different modeling techniques including • Geometrical Optics • Physical/Computational Optics • Local semi-analytical methods Combining Modeling Techniques Unif ied Modeling Geometrical Optics Thin element approximation (TEA) Finite differene time domain (FDTD) Layer matrices Fresnel integral Finite element method (FEM) Spectrum of plane waves (SPW) Beam propagation method (BPM) Rigorous coupled wave approach (RCWA) Fourier modal method (FMM) … more … Combining Modeling Techniques Unif ied Modeling Geometrical Optics Thin element approximation (TEA) Finite differene time domain (FDTD) Layer matrices Fresnel integral Finite element method (FEM) Spectrum of plane waves (SPW) Beam propagation method (BPM) Rigorous coupled wave approach (RCWA) Fourier modal method (FMM) … more … Modeling with Field Tracing Instead of ray bundles, are traced through the system. Field Tracing Applications Surface Scattering • Light propagation through surface profiles: – Requires a model or measurement data of scattering surface. – Rigorous or approximate light propagation depending on feature size and required simulation accuracy. • Approximate light propagation: – Thin element approximation – Geometrical optics • Rigorous light propagation: – – – – RCWA/FMM Integral method FEM FDTD Surface Scattering 200 mm 23 mm ? Focusing Laser beam Refractive beam shaper Target plane Surface Scattering • Polarization: linear polarized in x-direction • Laser Diameter (1/e2): 8 mm • Wavelength: 632 nm Surface Scattering Intensity of Top Hat generated by perfect lens. Surface Scattering • Measured height error of aspherical surface of beam shaper. • Measurement by Zygo interferometer. • Corresponds to phase modulation of 0.3λ. • Feature size: 25 µm – 3 mm Surface Scattering Measured intensity Simulated intensity (simulation combines geometrical and physical optics) Volume Scattering • Analytical scattering models for example by MieScattering: – Only spherical particles. – For coherent monochromatic light and plane wave only. – Volume scattering only No interaction between volume scattering and surfaces. • Numerical rigorous simulation: – Not limited to specific particles – For arbitrary coherent or partially coherent light – Modeling of interaction between volume scattering and surfaces. Volume Scattering • Typically rigorous electromagnetic simulation • Rigorous light propagation by: – – – – – RCWA/FMM Integral method FEM FDTD …. Volume Scattering PMMA with gold particles 100 nm - 200 nm size 1016 particles per m3 Grating surface 40 µm Plane wave λ=532nm Polarization: Ex Incident angle: 0° 50 µm Volume Scattering Grating Surface 1 µm 645 nm Volume Scattering • • • • • • • Analysis by Fourier Modal Method (FMM) Efficiency of transmitted orders ±1st orders of grating have not equal efficiency. Stray light appearys Transmitted light: 20.4% Reflected light: 7.3 % Absorbed light: 72.3% Outlook, Summary User Defined Modeling by Field Tracing • Simulation have been done with LightTrans VirtualLab™ which comes with a wide variety of components and associated modeling techniques. • Field tracing allows inclusion of any component with any associated modeling technique. • In order to take maximum benefit of this field tracing capability, VirtualLab™ provides a programmable component which can be used together with all other components. • Programming languages: – C# with the full VirtualLab™ programming library – User defined MATLAB® code can be used in VirtualLab™ User Defined Modeling by Field Tracing Light Source Detector Different modeling techniques Summary • Physical optical simulation of surface and volume scattering requires modeling of diffraction and interference effects. • Numerical simulation enables high flexibility of scattering simulations for various surface and particle shapes. • Field Tracing enables analysis of micro and macro structured components, different light sources and detectors. • Rigorous and approximate analysis is possible. Thank You! www.lighttrans.com [email protected]