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Toralf Scharf

Cette personne a quitté l’EPFL

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Publications associées (106)

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High power modular LED-based illumination system for lithography applications

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

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

Precision glass molding of high-resolution diffractive optical elements

Hans Peter Herzig, Toralf Scharf, Karin Prater

The demand of high resolution diffractive optical elements (DOE) is growing. Smaller critical dimensions allow higher deflection angles and can fulfill more demanding requirements, which can only be met by using electron-beam lithography. Replication techn ...

Spie-Int Soc Optical Engineering2016

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

Toralf Scharf, Wilfried Noell, Raoul Kirner

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

Transition of optical regime in miniaturized optical systems: light interactions beyond the refraction limit

Hans Peter Herzig, Toralf Scharf, Myun Sik Kim

We investigate the transition of optical regimes of miniaturized optical systems using two canonical examples, where the refraction of light limits the system performance. A ball-lens and a solid immersion lens (SIL) are considered, whose refractive respon ...

Spie-Int Soc Optical Engineering2016

Phase anomalies in Bessel-Gauss beams

Hans Peter Herzig, Toralf Scharf, Myun Sik Kim

Bessel-Gauss beams are known as non-diffracting beams. They can be obtained by focusing an annularly shaped collimated laser beam. Here, we report for the first time on the direct measurement of the phase evolution of such beams by relying on longitudinal- ...

Optical Society of America2012

Two step process for the fabrication of diffraction limited concave microlens arrays

Hans Peter Herzig, Toralf Scharf, Irène Antoinette Philipoussis

A two step process has been developed for the fabrication of diffraction limited concave microlens arrays. The process is based on the photoresist filling of melted holes obtained by a preliminary photolithography step. The quality of these microlenses has ...

2008

Full field dependence of primary aberrations in perturbed double-plane symmetric systems with a circular pupil

Toralf Scharf, Alessandro Grosso

This paper deals with the theory of primary aberrations for perturbed double-plane symmetric optical systems consisting of a combination of tilted and decentered surfaces and a circular pupil. First, the analytical expressions describing the full field beh ...

OPTICAL SOC AMER2020

Small-size microlens characterization by multiwavelength high-resolution interference microscopy

Hans Peter Herzig, Toralf Scharf, Myun Sik Kim

Microlenses are widely studied in two main areas: fabrication and characterization. Nowadays, characterization draws more attention because it is difficult to apply test techniques to microlenses that are used for conventional optical systems. Especially, ...

Optical Society of America2010

Tolerancing the surface form of aspheric microlenses manufactured by wafer-level optics techniques

Toralf Scharf, Wilfried Noell, Jeremy Béguelin

Tolerancing is an important step toward the fabrication of high-quality and cost-effective lens surfaces. It is critical for wafer-level optics, when up to tens of thousands microlenses are fabricated in parallel and whose surfaces cannot be formed individ ...

OPTICAL SOC AMER2020

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

Toralf Scharf, Wilfried Noell, Raoul Kirner, Jeremy Béguelin

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

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

Shaping intensity behind amplitude masks for proximity correction lithography: Design, measurement and realization

Hans Peter Herzig, Toralf Scharf, Qing Tan, David Nguyen, Krishnaparvathy Puthankovilakam

Proximity exposure techniques in lithography are getting more and more popular because of the cost of ownership advantage of mask aligners compared to projection systems. In this paper a gap between simulation and the final result, the prints will be close ...

Spie-Int Soc Optical Engineering2014

Scalar analytical expressions for the field dependence of Zernike polynomials in asymmetric optical systems with circular symmetric surfaces

Toralf Scharf, Alessandro Grosso

In this paper we derive scalar analytical expressions describing the full field dependence of Zernike polynomials in optical systems without symmetries. We consider the general case of optical systems constituted by arbitrarily tilted and decentered circul ...

2020

Optical characterization of high numerical aperture microlenses for quality assessment and fabrication process optimization

Toralf Scharf, Wilfried Noell, Jeremy Béguelin

Accurate characterization of high numerical aperture aspheric microlenses currently is a nonstandard procedure that remains an open challenge. Here, we present and discuss a characterization method based on interferometric and point spread function measure ...

OPTICAL SOC AMER2020

Measuring amplitude and phase of light emerging from microstructures with HRIM

Hans Peter Herzig, Toralf Scharf, Myun Sik Kim

Ultra high-resolution measurements of amplitude and phase fields emerging from fine period amplitude gratings are presented and discussed. In the axial direction periodically repeated features are found, whose origins are the Talbot effect within the Fresn ...

SPIE Digital Library2011

Phase anomalies in Talbot light carpets of selfimages

Hans Peter Herzig, Toralf Scharf, Myun Sik Kim

An interesting feature of light fields is a phase anomaly, which occurs on the optical axis when light is converging as in a focal spot. Since in Talbot images the light is periodically confined in both transverse and axial directions, it remains an open q ...

Optical Society of America2013

Photonic Nanojet engineering: Focal point shaping with scattering phenomena of dielectric microspheres

Hans Peter Herzig, Toralf Scharf, Myun Sik Kim

We experimentally engineer Nanojets produced by dielectric spheres by varying the illumination and observe the effect with a high-resolution interference microscope (HRIM). Converging and diverging spherical wavefronts and Bessel- Gauss beams are considere ...

SPIE2011

A bottom-up approach to fabricate optical metamaterials by self-assembled metallic nanoparticles

Toralf Scharf

We introduce a novel bottom-up approach to fabricate by self assembly a metamaterial from metallic nanoparticles in a two-step process. In the first step, a metamaterial made of densely packed silver nanoparticles is required. The material dispersion with ...

2012

Realization and Characterization of POLICRYPS-like Structures Including Metallic Subentities

Toralf Scharf

A first characterization of newly realized micro periodic structures including metallic nanoparticles is reported. The original mixture, generally utilized for the realization of polymer-liquid-crystal-polymer-slices gratings (POLICRYPS), has been enriched ...

2012

High Resolution Interference Microscopy: 3D measurement of focused light at 405nm applied to optical disc

Hans Peter Herzig, Toralf Scharf, Myun Sik Kim

High capacity data storage on DVD and optical discs is based on focused light beams. The characterization of light fields within the focus point is a very difficult task, which requires a high-resolution method like scanning near field optical microscopy ( ...

2009