Recherche

Afficher tous les résultats pour

Accueil

Personne

Toralf Scharf

Cette personne n’est plus à l’EPFL

À propos
Confidentialité
Mentions légales

Graph Chatbot

Publications associées (107)

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

Wilfried Noell, Toralf Scharf, 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

Are Photonic Nanojets Achromatic?

Myun Sik Kim, Toralf Scharf, Michail Symeonidis

In this work we study the evolution of the photonic nanojet (PNJ) phenomenon as the ratio of the sphere's diameter over the illumination wavelength changes, for microspheres with diameters from 2 mu m to 100 mu m. We measure the focal point position by usi ...

SPIE-INT SOC OPTICAL ENGINEERING2019

Leveraging wafer-level manufacturing process limitations to increase large scale fused silica microlens array uniformity

Wilfried Noell, Toralf Scharf, Jeremy Béguelin, Raoul Kirner

The wafer-level production of Fused Silica microlens arrays is limited by systematic process non-uniformities. The common molten resist-reflow process with subsequent dry-etching allows for manufacturing of microlens arrays on 200 mm wafers. A thorough pro ...

SPIE-INT SOC OPTICAL ENGINEERING2019

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

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

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

Diffractive Optical Elements Investigation in the Phase Domain

Myun Sik Kim, Toralf Scharf, Michail Symeonidis, Dong Cheon Kim

In this work we demonstrate the advantages of investigating diffractive optical elements in the phase domain. In this regime we can detect features that are not restrained by the diffraction limit and relate them to the geometrical and optical properties o ...

SPIE-INT SOC OPTICAL ENGINEERING2019

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

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

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

Printing sub-micron structures using Talbot mask-aligner lithography with a 193 nm CW laser light source

Wilfried Noell, Toralf Scharf, Raoul Kirner, Andreas Vetter

A continuous improvement of resolution in mask-aligner lithography is sought after to meet the requirements of an ever decreasing minimum feature size in back-end processes. For periodic structures, utilizing the Talbot effect for lithography has emerged a ...

2018

High power modular LED-based illumination system for lithography applications

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

Mask-aligner lithography is a technology used to transfer patterns with critical dimensions in the micrometer range from below 1 micron for contact printing to a dozen of microns in proximity printing. This technology is widely used in the fabrication of M ...

2018

Mask-aligner Talbot lithography using a 193 nm CW light source

Wilfried Noell, Toralf Scharf, Raoul Kirner, Andreas Vetter

We present and discuss Talbot mask-aligner lithography, relying on a continuous wave laser emitting at 193nm for the illumination. In this source, a diode laser at 772nm is amplified by a tapered amplifier in master-oscillator power-amplifier configuration ...

2018

Aberrations analysis of a Focused Plenoptic Camera

Toralf Scharf, Alessandro Grosso

A Focused Plenoptic Camera in Galilean configuration is studied and its aberrations behavior is interpreted with the Nodal Aberration Theory (NAT). Sequential ray tracing is applied to individual optical channels constituted by the camera objective and ind ...

2018

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

Wilfried Noell, Toralf Scharf, Xiaolong Wang, Raoul Kirner, Andreas Vetter

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

Wilfried Noell, Toralf Scharf, 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

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

Toralf Scharf, Friedrich Daniel Werdehausen

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

High-power modular LED-based illumination systems for mask-aligner lithography

Hans Peter Herzig, Toralf Scharf, Johana Bernasconi

Mask-aligner lithography is traditionally performed using mercury arc lamps with wavelengths ranging from 250 nm to 600 nm with intensity peaks at the i, g and h lines. Since mercury arc lamps present several disadvantages, it is of interest to replace the ...

2018

Improved calibration of vertical scanning optical profilometers for spherical profiles measurements

Wilfried Noell, Toralf Scharf, Jeremy Béguelin

A new method for calibrating optical scanning profilometers is presented. Especially adapted to spherical and aspherical profile measurements, it shows an increase of accuracy bigger than one order of magnitude for radius of curvature measurements. Calibra ...

2018

Experimental demonstration of ray-rotation sheets

Toralf Scharf

We have built microstructured sheets that rotate, on transmission, the direction of light rays by an arbitrary, but fixed, angle around the sheet normal. These ray-rotation sheets comprise two pairs of confocal lenticular arrays. In addition to rotating th ...

2018

Enabling proximity mask-aligner lithography with a 193nm CW light source

Wilfried Noell, Toralf Scharf, Raoul Kirner, Andreas Vetter

We introduce a novel industrial grade 193nm continuous-wave laser light source for proximity mask-aligner lithography. A diode seed laser in master-oscillator power-ampliﬁcation conﬁguraton is frequency-quadrupled using lithiumtriborate and potassium-ﬂuoro ...

2018

Characterization of crystallographically etched single crystal diamond diffraction gratings

Niels Quack, Olivier Martin, Toralf Scharf, Marcell Kristof Kiss

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

Page 2 sur 6