Publications by Toralf Scharf | EPFL Graph Search

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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 ...

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 ...

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 ...

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 ...

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 ...

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 ...

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 ...

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 ...

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 ...

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 ...

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 ...

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 ...

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 ...

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 ( ...

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 ...

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) ...

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, ...

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 ...

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 ...

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 ...

Toralf Scharf

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

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

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

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

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

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

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

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

Measuring amplitude and phase of light emerging from microstructures with HRIM

Phase anomalies in Talbot light carpets of selfimages

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

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

Realization and Characterization of POLICRYPS-like Structures Including Metallic Subentities

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

Adjoint-based Optimization for Diffractive Beam-Splitters

Array imaging system for lithography

Engineered nanostructures' characterization by spectral interferometric microscopy

Interferometric Measurement on a Nanometric Length Scale

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

Characterization of crystallographically etched single crystal diamond diffraction gratings