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Toralf Scharf

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Publications associées (107)

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

Hans Peter Herzig, Myun Sik Kim, Toralf Scharf

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

Understanding of photocurrent enhancement in real thin film solar cells: towards optimal onedimensional gratings

Christophe Ballif, Hans Peter Herzig, Karin Söderström, Vincent Paeder, Toralf Scharf, Ali Naqavi

Despite the progress in the engineering of structures to enhance photocurrent in thin film solar cells, there are few comprehensive studies which provide general and intuitive insight into the problem of light trapping. Also, lack of theoretical propositio ...

Optical Society of America2011

Measuring amplitude and phase of light emerging from microstructures with HRIM

Hans Peter Herzig, Myun Sik Kim, Toralf Scharf

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

Nanostructured surface fabricated by laser interference lithography to attenuate the reflectivity of microlens arrays

Pierre-Yves Baroni, Hans Peter Herzig, Toralf Scharf

A subwavelength-scale square lattice optical nanostructure is fabricated using an interference photolithography process on the surface of a quartz microlens array. This nanostructuring of the quartz surface introduces an antireflective effect, reducing ref ...

2010

An RCWA Analysis of Solar Cell Back Reflectors: Comparison between Modelling and Experiment

Christophe Ballif, Hans Peter Herzig, Karin Söderström, Vincent Paeder, Toralf Scharf, Franz-Josef Haug, Ali Naqavi

We present a comparison between spectrally-resolved reflection measurements of gratings and theoretical predictions from RCWA approach. Diffraction intensities vary significantly with polarization, and surface plasmon absorption is observed around the onse ...

2010

Measurements of light fields emerging from fine amplitude gratings

Hans Peter Herzig, Myun Sik Kim, Toralf Scharf

High resolution amplitude and phase of light fields emerging from a 2-μm-period amplitude grating are measured for different wavelengths. The amplitude gratings lead to highly periodic patterns caused by the Talbot effect. Such patterns reach periodicities ...

2010

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

Hans Peter Herzig, Myun Sik Kim, Toralf Scharf

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

Amplitude and Phase Fields of Photonic Nanojets

Hans Peter Herzig, Myun Sik Kim, Toralf Scharf

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

Experimental demonstration of ray-optical refraction with confocal lenslet arrays

Toralf Scharf

We observe imaging through windows comprising pairs of confocal lenslet arrays that have different focal lengths but that are otherwise identical. Image space is stretched in the longitudinal direction only. Such windows are examples of METATOYs, optical c ...

Optical Society of America2010

Fabrication and characterization of linear diffusers based on concave micro lens arrays

Nico de Rooij, Hans Peter Herzig, Wilfried Noell, Roland Andreas Bitterli, Toralf Scharf

We present a new approach of beam homogenizing elements based on a statistical array of concave cylindrical microlens arrays. Those elements are used to diffuse light in only one direction and can be employed together with fly’s eye condensers to generate ...

Optical Society of America2010

Field of view extension using satellite pinhole cameras

Hans Peter Herzig, Toralf Scharf

An approach to extend the field of view of a miniaturised imaging system is introduced. This innovative approach uses multiple optical systems working in parallel and image post-processing. As an example, a module consisting of a central single micro-lens ...

2010

Switchable photonic crystal cavity by liquid crystal infiltration

Pierre-Yves Baroni, Hans Peter Herzig, Armando Cosentino, Vincent Paeder, Qing Tan, Toralf Scharf

We report on the fabrication and optical characterization of a switchable photonic crystal nanocavity actuated by liquid crystals. This device acts as a filter presenting a transmission peak around the telecom wavelength λ = 1550 nm. Passing from the isotr ...

European Optical Society2010

Fabrication and Characterization of 1-D diffusing elements

Hans Peter Herzig, Roland Andreas Bitterli, Myun Sik Kim, Toralf Scharf

Certain high power laser applications require thin homogeneous laser lines. In this paper we describe the concept, fabrication and characterization of a 1-D diffuser that generates such a line. The device is based on an array of concave cylinder lenses wit ...

2009

Dynamic array spot shaping for laser micro machining

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

2009

High resolution displacement detection with speckles

Hans Peter Herzig, Toralf Scharf

2009

Gas Detection with a Micro FTIR Spectrometer in the MIR Region

Nico de Rooij, Hans Peter Herzig, Danick Briand, Toralf Scharf

We report on the application of a silicon micromachined lamellar grating interferometer in a Fourier Transform Infrared (FTIR) spectrometer for the detection of gases in the mid-infrared (MIR) region. The FTIR spectrometer was equipped with MIR optical fib ...

Elsevier2009

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

Hans Peter Herzig, Myun Sik Kim, Toralf Scharf

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

Lamellar grating interferometer in a Fourier transform IR spectrometer

Hans Peter Herzig, Toralf Scharf

2009

Multifunctional Micro-Optical Elements for Laser Beam Homogenizing and Beam Shaping

Nico de Rooij, Hans Peter Herzig, Roland Andreas Bitterli, Toralf Scharf

2008

Microlenses on Bragg Reflectors to Create Iridescent Colors

Hans Peter Herzig, Toralf Scharf

In nature strong colors play an important role in scaring away predators or finding a mate. Often, the strongest and brightest colors arise from coherent scattering and reflection on periodic structures on a length scale of several micro- or nanometers. Un ...

2008

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