Stephan Reichelt
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View article: Effect of sample thickness on etching rate:Simulations and experiments
Effect of sample thickness on etching rate:Simulations and experiments Open
Precision optical elements such as computer generated holograms (CGH) for optical testing or optical elements for high-power lasers, e.g. pulse compression gratings, are often many millimeters thick. This study investigates the effect of s…
View article: Corrigendum to “Comparison of rigorous scattering models to accurately replicate the behaviour of scattered electromagnetic waves in optical surface metrology” [Journal of Computational Physics, 521 (2025), 1-21/113519]
Corrigendum to “Comparison of rigorous scattering models to accurately replicate the behaviour of scattered electromagnetic waves in optical surface metrology” [Journal of Computational Physics, 521 (2025), 1-21/113519] Open
View article: Influence of object motion on roughness measurements using spectral speckle correlation
Influence of object motion on roughness measurements using spectral speckle correlation Open
Spectral speckle correlation (SSC) enables fast, non-contact surface-roughness metrology, but object motion usually degrades its accuracy. We aim to enable measurements on moving objects and present a unified model that separates the total…
View article: Improved far-field holograms using spatial light modulators and camera-in-the-loop optimization
Improved far-field holograms using spatial light modulators and camera-in-the-loop optimization Open
View article: Lensless magneto-optical imaging
Lensless magneto-optical imaging Open
View article: Large area roughness measurements using spectral speckle correlation
Large area roughness measurements using spectral speckle correlation Open
Surface roughness is a critical quality parameter in metal sheet processing, yet the current measurement methods are limited and just capable of assessing areas of up to a few square millimeters in-line. A fast measurement of larger areas …
View article: Enhanced Vectorial Measurement Uncertainty Model
Enhanced Vectorial Measurement Uncertainty Model Open
Quantitative determination of the uncertainty of a measurement result is the key to assessing the quality and reliability of a measurement process and its result. The comparability of measurement results is ensured by the method for evalua…
View article: Digital Twins for 3D Confocal Microscopy: Near-Field, Far-Field, and Comparison with Experiments
Digital Twins for 3D Confocal Microscopy: Near-Field, Far-Field, and Comparison with Experiments Open
To push the boundaries of confocal microscopy beyond its current limitations by predicting sensor responses for complex surface geometries, we build digital twins using three rigorous models, the finite element method (FEM), Fourier modal …
View article: Bimodal tissue differentiation using hyperspectral imaging and elastographic Fourier transform profilometry
Bimodal tissue differentiation using hyperspectral imaging and elastographic Fourier transform profilometry Open
View article: Advanced Imaging‐Based Metrology for Precise Deformation Monitoring: Railway Bridge Case Study
Advanced Imaging‐Based Metrology for Precise Deformation Monitoring: Railway Bridge Case Study Open
In this article, two advanced imaging‐based metrology methods, the multipoint method and the tele‐wide‐angle method, are introduced to the field of structural health monitoring. Both provide the means to significantly improve either the me…
View article: Holographic detection for fast fringe projection profilometry of deep micro-scale objects
Holographic detection for fast fringe projection profilometry of deep micro-scale objects Open
Phase-shifting Fringe projection profilometry (FPP) excels in 3D measurements for many macro-scale applications, but as features-of-interest shrink to the microscopic scale, depth-of-field limitations slow measurements and necessitate mech…
View article: Comparison of rigorous scattering models to accurately replicate the behaviour of scattered electromagnetic waves in optical surface metrology
Comparison of rigorous scattering models to accurately replicate the behaviour of scattered electromagnetic waves in optical surface metrology Open
Rigorous scattering models are based on Maxwell's equations and can provide high-accuracy solutions to model electromagnetic wave scattering from objects. Being able to calculate the scattered field from any surface geometry and considerin…
View article: Fast Fringe Projection Profilometry of Deep Micro-Scale Objects using Holographic Detection
Fast Fringe Projection Profilometry of Deep Micro-Scale Objects using Holographic Detection Open
Phase-shifting Fringe Projection Profilometry (FPP) is the state-of-the-art 3D measurement technique for many macroscopic applications, but as necessary object details become microscopic, depth-of-field slows measurements and requires mech…
View article: Fast Fringe Projection Profilometry of Deep Micro-Scale Objects using Holographic Detection
Fast Fringe Projection Profilometry of Deep Micro-Scale Objects using Holographic Detection Open
Phase-shifting Fringe Projection Profilometry (FPP) is the state-of-the-art 3D measurement technique for many macroscopic applications, but as necessary object details become microscopic, depth-of-field slows measurements and requires mech…
View article: Two-wavelength holographic micro-endoscopy
Two-wavelength holographic micro-endoscopy Open
In this paper, we present a method for micro-endoscopic topography measurement utilizing two-wavelength holography. Initially, we evaluate the inter-core dispersion and cross-talk of two commercially available imaging fiber bundles (CFBs) …
View article: Technology Selection for Inline Topography Measurement with Rover-Borne Laser Spectrometers
Technology Selection for Inline Topography Measurement with Rover-Borne Laser Spectrometers Open
This work studies enhancing the capabilities of compact laser spectroscopes integrated into space-exploration rovers by adding 3D topography measurement techniques. Laser spectroscopy enables the in situ analysis of sample composition, aid…
View article: Spectral speckle displacement in defocused and tilted imaging systems
Spectral speckle displacement in defocused and tilted imaging systems Open
Speckle patterns offer valuable insights into the surface characteristics or the characteristics of the light generating the speckle. One possible way to extract this information is via spectral speckle correlation (SSC). The cross-correla…
View article: Lensless imaging in one shot using the complex degree of coherence obtained by multiaperture interferences
Lensless imaging in one shot using the complex degree of coherence obtained by multiaperture interferences Open
The van Cittert–Zernike theorem states that the Fourier transform of the intensity distribution function of a distant, incoherent source is equal to the complex degree of coherence. In this Letter, we present a method for measuring the com…
View article: Lensless microscopy by multiplane recordings: sub-micrometer, diffraction-limited, wide field-of-view imaging
Lensless microscopy by multiplane recordings: sub-micrometer, diffraction-limited, wide field-of-view imaging Open
Lensless microscopy is attractive because lenses are often large, heavy and expensive. We report diffraction-limited, sub-micrometer resolution in a lensless imaging system that does not need a reference wave and imposes few restrictions o…
View article: Retrace error calibration for interferometric measurements using an unknown optical system
Retrace error calibration for interferometric measurements using an unknown optical system Open
In classical interferometric null test measurements, the measurement and reference beam path should be the same. A difference in the beam paths results in the so called retrace error. One very common approach to avoid retrace errors is to …
View article: Field evaluation of a novel holographic single-image depth reconstruction sensor
Field evaluation of a novel holographic single-image depth reconstruction sensor Open
A camera-based single-image sensor is presented, that is able to measure the distance of one or multiple object points (light emitters). The sensor consists of a camera, whose lens is upgraded with a diffractive optical element (DOE). It f…
View article: Complex illumination system for fast interferometric measurements
Complex illumination system for fast interferometric measurements Open
Freeform metrology is an enabling technology for today’s research and advanced manufacturing. The Tilted Wave Interferometer is a full field measurement system for fast and flexible measurements. It is based on an off-axis illumination sch…
View article: Two-wavelength digital holography through fog
Two-wavelength digital holography through fog Open
Interferometric detection enables the acquisition of the amplitude and phase of the optical field. By making use of the synthetic wavelength as a computational construct arising from digital processing of two off-axis digital holograms, it…
View article: Advantages of holographic imaging through fog
Advantages of holographic imaging through fog Open
In this paper, we demonstrate digital holographic imaging through a 27-m-long fog tube filled with ultrasonically generated fog. Its high sensitivity makes holography a powerful technology for imaging through scattering media. With our lar…
View article: PHOTONICS METROLOGY IN THE NANOSCALE
PHOTONICS METROLOGY IN THE NANOSCALE Open
Optical metrology at the nanoscale level is a sophisticated task, where often model-based approaches are utilized. We discuss scatterometry in an advanced implementation as well as some of the capabilities of our Nanopositioning and Nanome…
View article: Physics-enhanced neural network for phase retrieval from two diffraction patterns
Physics-enhanced neural network for phase retrieval from two diffraction patterns Open
In this work, we propose a physics-enhanced two-to-one Y-neural network (two inputs and one output) for phase retrieval of complex wavefronts from two diffraction patterns. The learnable parameters of the Y-net are optimized by minimizing …
View article: Interferometric radius of curvature measurements: an environmental error treatment
Interferometric radius of curvature measurements: an environmental error treatment Open
Interferometric determination of sphere radii is a well known technique. To keep accuracy high and uncertainties low, a precisely controlled environment is usually necessary. Environmental changes in temperature lead to time dependent drif…
View article: Accurate single image depth detection using multiple rotating point spread functions
Accurate single image depth detection using multiple rotating point spread functions Open
In this article we present the simulation and experimental implementation of a camera-based sensor with low object-space numerical aperture that is capable of measuring the distance of multiple object points with an accuracy of 8.51 µm ove…
View article: Holographic single-image depth reconstruction
Holographic single-image depth reconstruction Open
In this article a camera-based single-image sensor is presented, that is able to measure the distance of multiple object points. The experimental results show an accuracy of 8,51 μm within a depth range of 20 mm. The sensor consists of a c…