A5047176758- Orbital Angular Momentum in Optics
- Corneal surgery and disorders
- Spectroscopy Techniques in Biomedical and Chemical Research
- Terahertz technology and applications
- Optical and Acousto-Optic Technologies
- Optical Polarization and Ellipsometry
- Optical measurement and interference techniques
- Photonic and Optical Devices
- Electromagnetic Scattering and Analysis
- Electromagnetic Fields and Biological Effects
- Millimeter-Wave Propagation and Modeling
- Numerical methods in engineering
- Ultrasound Imaging and Elastography
- Optical Coatings and Gratings
- Spectroscopy and Laser Applications
- Radio Astronomy Observations and Technology
- Advanced Fluorescence Microscopy Techniques
- Semiconductor Lasers and Optical Devices
- Radio Wave Propagation Studies
- Advanced Numerical Analysis Techniques
- Wireless Body Area Networks
- Near-Field Optical Microscopy
- Photoacoustic and Ultrasonic Imaging
- Numerical methods in inverse problems
- Electromagnetic Simulation and Numerical Methods
Aalto University
2021-2025
Terahertz spectroscopy is a promising method to diagnose ocular diseases, where the cornea typically imaged by Gaussian beams. However, beam’s mismatch with cornea’s spherical surface produces 5-10 % error in analysis. We investigate wavefront-modified vector beams, reducing original analysis less than 0.5 %. Vector beams are synthesized our developed 3D Angular Spectrum Method expanded harmonic presentation, allowing wavefront modification and scattering from 100-layer models. show that...
Coupling to longitudinal modes of thin spherical shells, under Gaussian-beam illumination, was explored with a theoretical method based on Fourier-optics analysis and vector harmonics scrutinized an experimental setup. For the theory part, illumination frequency band fixed between 100-600 GHz outer shell radius curvature thickness are 7.5 mm 0.5 mm, respectively. The material either lossless cornea or aqueous effective media representing cornea. Six different beam-target strategies were...
Mie theory is a powerful method to model electromagnetic scattering from multilayered sphere. Usually, the incident beam expanded its vector spherical harmonic representation defined by shape coefficients, and multilayer sphere obtained T-matrix method. However, obtaining coefficients for arbitrarily shaped beams has limitations on source locations requires different methods when inside or outside computational domain at scatterer surface. We propose 3D angular spectrum defining arbitrary...
Improving the longitudinal modes coupling in layered spherical structure contributes significantly to corneal terahertz sensing, which plays a crucial role early diagnosis of cornea dystrophies. Using steel sphere calibrate reflection from sample assists enhancing resolution modes. The requirement and challenges toward applying calibration are introduced addressed. Six corneas with different properties spotted study effect perturbations frequency range 100 GHz 600 GHz. A particle-swarm...
The feasibility of a 220 - 330 GHz zero order axicon generated Bessel beam for corneal water content was explored. Simulation and experimental data from the 25-degree cone angle hyperbolic-axicon lens illuminating metallic spherical targets demonstrate monotonically decreasing, band integrated, backscatter intensity increasing radius curvature 7 11 mm, when reflector optical axis are aligned. Further, radii >= 9.5 maximum signal obtained with 1 mm transverse displacement between axes arising...
The angular spectrum method is an efficient approach for synthesizing electromagnetic beams from planar electric field distributions. definition restricted to a plane, which can introduce inaccuracy when applying the synthesized beam curved surface features. also be interpreted as pure source defining symmetrically with respect creation plane. Recently, we generalized that symmetric arbitrary distributions, are valid at any point on compact, regular Ω in
Ocular diseases can be detected in early-stage with non-destructive terahertz imaging by analyzing cornea thickness and water content changes. We propose wavefront-modified spherical vector beam imaging, which reduces nominal 4-5 % super-confocally focused Gaussian errors to less than 0.1 %.
The angular spectrum method is a rigorous to synthesize near and far-field electromagnetic beams from planar field distributions. However, this limitation of surfaces has restricted its applicability with simple focal planes. We propose curved boundary integral (CBIM) arbitrary address expand the method's scope between shaped objects. This study presents detailed theoretical framework behind CBIM validates effectiveness accuracy comprehensive set simulations. Additionally, we present...
Wave scattering from a human cornea illuminated with submillimeter-wave Gaussian beam is explored Fourier analysis. This new approach enabled us to investigate the as coated sphere rather than homogenized one. The was modeled an aqueous spherical shell using effective medium theory, 60 percent water, enclosing of pure water. corneal model at 220 GHz - 330 GHz. interaction incident and back-reflected beam, back-scattered field, back-scattering one usual beam-cornea alignment scheme were...
Submillimeter-wave and THz sensing of cornea leverage the layered tissue structure for assessments corneal water content thickness. The is bounded by air on anterior an optically thick body posterior thus presents as a lossy thin film lying atop termination. Resolution cornea's longitudinal modes via frequency domain reflectometry in band sufficiently low (e.g. 220 GHz – 330 GHz) significant penetration allows simultaneous estimates (CTWC) central thickness (CCT). However, since spherical,...
The feasibility of a 220 - 330 GHz zero order axicon generated Bessel beam for corneal water content was explored. Simulation and experimental data from the 25-degree cone angle hyperbolic-axicon lens illuminating metallic spherical targets demonstrate monotonically decreasing, band integrated, backscatter intensity increasing radius curvature 7 11 mm, when reflector optical axis are aligned. Further, radii >= 9.5 maximum signal obtained with 1 mm transverse displacement between axes...
Mie theory is a powerful method to model electromagnetic scattering from multilayered sphere. Usually, the incident beam expanded its vector spherical harmonic representation defined by shape coefficients, and multilayer sphere obtained T-matrix method. However, obtaining coefficients for arbitrarily shaped beams has limitations on source locations requires different methods when inside or outside computational domain at scatterer surface. We propose 3D angular spectrum defining arbitrary...
An efficient Fourier optics method for synthesizing a required incident beam to compute the internal and scattered electromagnetic fields from known spherical surface electric field distribution is presented.
Coupling to longitudinal modes of thin spherical shells, under Gaussian-beam illumination, was explored with a theoretical method based on Fourier-optics analysis and vector harmonics. The illumination frequency band fixed between 100-600 GHz the outer shell radius curvature thickness are 7.5 mm 0.5 mm, respectively. material either lossless cornea or an aqueous effective media representing cornea. Six different beam-target strategies were introduced being potential candidates for maximum...