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Toralf Scharf

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Related publications (106)

Page 3 of 6

Adjoint-based Optimization for Diffractive Beam-Splitters

Toralf Scharf, Dong Cheon Kim

Computational optimization of diffractive elements is often limited by a large number of design parameters. Adjoint method allows the gradient of target function respect to all design variables to be calculated with only two electromagnetic simulations. We ...

IEEE2019

Array imaging system for lithography

Toralf Scharf, Wilfried Noell, Raoul Kirner

We present an integrated array imaging system based on a stack of microlens arrays. The microlens arrays are manufactured by melting resist and reactive ion etching (RIE) technology on 8'' wafers (fused silica) and mounted by wafer-level packaging (WLP)(1) ...

Spie-Int Soc Optical Engineering2016

Engineered nanostructures' characterization by spectral interferometric microscopy

Toralf Scharf, Michail Symeonidis

We characterize engineered nanostructures with sizes smaller than half a wavelength using spectrally resolved interferometry. We analyze the response of the meta-atom of interest, which has a raspberry-like geometry. To identify the origin of the response, ...

SPIE-INT SOC OPTICAL ENGINEERING2019

Interferometric Measurement on a Nanometric Length Scale

Hans Peter Herzig, Toralf Scharf, Myun Sik Kim

We investigate a measurement technique based on High Resolution Interference Microscopy (HRIM). HRIM allows the characterization of amplitude and phase of electromagnetic wave-fields in the far-field with a spatial accuracy that corresponds to a few nanome ...

2008

High-quality single crystal diamond diffraction gratings fabricated by crystallographic etching

Olivier Martin, Toralf Scharf, Niels Quack, Christian Santschi, Teodoro Graziosi, Marcell Kristof Kiss, Adrien Marc Toros

We demonstrate a novel method for fabricating single crystal diamond diffraction gratings based on crystallographic etching that yields high-quality diffraction gratings from commercially available diamond plates. Both V-groove and rectangular gratin ...

2019

Characterization of crystallographically etched single crystal diamond diffraction gratings

Olivier Martin, Toralf Scharf, Niels Quack, Marcell Kristof Kiss, Adrien Marc Toros

We report on the fabrication and experimental characterization of single crystal diamond diffraction gratings fabricated with crystallographic dry etching. High aspect ratio atomic force microscopy reveals a characteristic V-groove profile exhibiting smoot ...

IEEE2018

Gouy phase anomaly in photonic nanojets

Hans Peter Herzig, Toralf Scharf, Myun Sik Kim

We investigate in real space amplitude and phase distributions of light in photonic nanojets emerging from micrometer-sized dielectric spheres with a high-resolution interference microscope. Strong localization of light and a Gouy phase anomaly are witness ...

American Institute of Physics2011

Multiple Phase Anomalies in Bessel Beam

Hans Peter Herzig, Toralf Scharf, Myun Sik Kim

The non-diverging feature of the Bessel-kind beam leads to multiple phase anomalies along the optical axis in contrary to the focused Gaussian beam. Here, we analyze the phase distributions using in a longitudinal-differential phase mode of a high-resoluti ...

2013

Specification of aspherical surfaces used as refractive elements in micro-optical systems

Toralf Scharf, Wilfried Noell, Jeremy Béguelin

The optical performance of refractive plano-convex microlenses is mainly related to the quality of their (a)spherical surface. An efficient tolerancing of this surface is a key step towards the manufacturing of high quality microlenses. However, we demonst ...

SPIE-INT SOC OPTICAL ENGINEERING2019

Semiconductor-based narrow-line and high-brilliance 193-nm laser system for industrial applications

Toralf Scharf, Wilfried Noell, Raoul Kirner, Xiaolong Wang

We present a novel industrial-grade prototype version of a continuous-wave 193 nm laser system entirely based on solid state pump laser technology. Deep-ultraviolet emission is realized by frequency-quadrupling an amplified diode laser and up to 20 mW of o ...

2018

Assessing microlens quality based on 3D irradiance measurement at the focal spot area

Toralf Scharf, Wilfried Noell, Jeremy Béguelin, Michail Symeonidis

During the fabrication process of microlenses, characterization is essential for two purposes: evaluate the optical quality of the element and provide surface information feedback for process optimization. However, no technique can fulfill these two object ...

2018

Axial phase measurements of light interacting with microstructures

Hans Peter Herzig, Toralf Scharf, Myun Sik Kim

We present an experimental method to study field structures of highly confined light after interaction with microstructures. A high-resolution interference microscope (HRIM) allows us to measure the three-dimensional (3D) amplitude and phase distributions ...

Spie-Int Soc Optical Engineering, Po Box 10, Bellingham, Wa 98227-0010 Usa2012

Simulation of microoptics under inhomogeneous illumination: Sinusoidal Phase Grating under Gaussian Beam Illumination

Toralf Scharf, Maryam Yousefi

Far field pattern generation is investigated for thick sinusoidal phase grating under a Gaussian beam illumination to obtain a high field of view. We compare the Fraunhofer approximation with the High-NA propagator and demonstrate that the Fraunhofer appro ...

IEEE2019

Using effective medium theories to design tailored nanocomposite materials for optical systems

Toralf Scharf

Modern optical systems are subject to very restrictive performance, size and cost requirements. Especially in portable systems size often is the most important factor, which necessitates elaborate designs to achieve the desired specifications. However, cur ...

2018

Limit of light coupling strength in solar cells

Christophe Ballif, Hans Peter Herzig, Toralf Scharf, Franz-Josef Haug, Ali Naqavi

We introduce a limit for the strength of coupling light into the modes of solar cells. This limit depends on both a cell’s thickness and its modal properties. For a cell with refractive index n and thickness d, we obtain a maximal coupling rate of $2c\sqrt ...

American Institute of Physics2013

Amplitude and Phase Fields of Photonic Nanojets

Hans Peter Herzig, Toralf Scharf, Myun Sik Kim

We report on advanced 3D direct imaging of light fields emerging from a photonic nanojet. We used an interference microscope that allows observation of amplitude and phase at the highest resolution. For the first time cross polarization interferometry is u ...

2010

Spatial coherence properties of an LED-based illumination system for mask-aligner lithography

Hans Peter Herzig, Toralf Scharf, Wilfried Noell, Raoul Kirner, Johana Bernasconi

A high-power LED-based illumination system has been developed as a replacement for the mercury arc lamps used in mask-aligner lithography. LEDs are arranged in a grid array and placed in the entrance aperture of individual reflectors. Those reflectors decr ...

SPIE2019

Dynamic array spot shaping for laser micro machining

Toralf Scharf, Wilfried Noell, Roland Andreas Bitterli, Jonathan Masson

2009

Light confinement effect of non-spherical nanoscale solid immersion lenses

Hans Peter Herzig, Toralf Scharf, Myun Sik Kim, Gaël David Osowiecki, David Nguyen

We report on the light confinement effect observed in non-ideally shaped (i.e., non-spherical) nanoscale solid immersion lenses (SILs). To investigate this effect, nanostructures of various shapes are fabricated by electron-beam lithography. When completel ...

Spie-Int Soc Optical Engineering2013

Plano-concave mini-lens array for plenoptic imaging applications

Toralf Scharf, Alessandro Grosso

An array of plano-concave mini-lenses is designed to realize a particular version of Light Field camera known as Plenoptic Camera 1.2. The Delano diagram related to the on-axis optical channel of such a camera is computed to show its retro-focus behavior a ...

IEEE2019