Adrian Grewe

Technische Universität Ilmenau

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Stefan Sinzinger

Technische Universität Ilmenau

Matthias Hillenbrand

Carl Zeiss (Germany)

Beate Dr.-Ing. Mitschunas

Technische Universität Ilmenau

Martin Hoffmann

Ruhr University Bochum

Csaba Endrödy

Technische Universität Ilmenau

Hans Zappe

University of Freiburg

Andreas Seifert

CIC nanoGUNE

Phuong-Ha Cu-Nguyen

University of Freiburg

Roman Kleindienst

Carl Zeiss (Germany)

Daniela Hoffmann

German Institute of Human Nutrition

Cooperative Institutions

Technische Universität Ilmenau

University of Freiburg

CiS Research Institute for Micro Sensors and Photovoltaics

University of Giessen

Fraunhofer Institute for Applied Solid State Physics

Microsystems (United Kingdom)

German Centre for Cardiovascular Research

Ludwig-Maximilians-Universität München

Fraunhofer Society

University of Bremen

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Efficient quantization of tunable helix phase plates

Optics Letters (2016)

Adrian Grewe Stefan Sinzinger

Helix phase plates are used in a variety of applications from optical trapping to astronomy. Tunable helix phase plates based on the Alvarez-Lohmann principle allow variation of the topological charge of the helix by rotating the phase plates with respect to each other around the optical axis. Current designs generate an undesired inverse phase in the section determined by the rotation angle. We present tunable phase plates that use a special quantization to maintain a uniform phase over the tuning range, suppressing the undesired part. As one benefit, the efficiency of the elements is increased over the whole tuning range.

Helix (gastropod)

Optical vortex

10.1364/ol.41.004755

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Citations (8)

An imaging spectrometer employing tunable hyperchromatic microlenses

Light Science & Applications (2015)

Phuong-Ha Cu-Nguyen Adrian Grewe Patrik Feßer Andreas Seifert Stefan Sinzinger

We present the design, fabrication and characterization of hydraulically-tunable hyperchromatic lenses for two-dimensional (2D) spectrally-resolved spectral imaging. These hyperchromatic lenses, consisting of a positive diffractive lens and a tunable concave lens, are designed to have a large longitudinal chromatic dispersion and thus axially separate the images of different wavelengths from each other. 2D objects of different wavelengths can consequently be imaged using the tunability of the lens system. Two hyperchromatic lens concepts are demonstrated and their spectral characteristics as well as their functionality in spectral imaging applications are shown.

Chromatic aberration

Characterization

10.1038/lsa.2016.58

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Citations (31)

Integration of an opto-chemical detector based on group III-nitride nanowire heterostructures

Applied Optics (2015)

Roman Kleindienst Pascal Becker V. Cimalla Adrian Grewe Pascal Hille

The photoluminescence intensity of group III nitrides, nanowires, and heterostructures (NWHs) strongly depends on the environmental H(2) and O(2) concentration. We used this opto-chemical transducer principle for the realization of a gas detector. To make this technology prospectively available to commercial gas-monitoring applications, a large-scale laboratory setup was miniaturized. To this end the gas-sensitive NWHs were integrated with electro-optical components for optical addressing and read out within a compact and robust sensor system. This paper covers the entire realization process of the device from its conceptual draft and optical design to its fabrication and assembly. The applied approaches are verified with intermediate results of profilometric characterizations and optical performance measurements of subsystems. Finally the gas-sensing capabilities of the integrated detector are experimentally proven and optimized.

Realization (probability)

10.1364/ao.54.000839

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Aberration analysis of optimized Alvarez–Lohmann lenses

Applied Optics (2014)

Adrian Grewe Matthias Hillenbrand Stefan Sinzinger

In this paper aberrations in Alvarez-Lohmann lenses are analyzed, and a semi-analytical strategy for compensation is derived. An x-y polynomial model is used to describe the aberrations and classify them into static and dynamic components. The lenses are enhanced by higher-order polynomials, and a numerical optimization process is used to determine the most influential coefficients. Two simulations of corrected systems are presented. The first one is optimized for on-axis imaging. The second system is optimized for multiple field points and shows the limitations of a single Alvarez-Lohmann lens. Two systems overcoming these limitations by introducing additional optical surfaces are presented, and their performance is analyzed in simulations.

10.1364/ao.53.007498

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Citations (28)

Wavefront-coding technique for inexpensive and robust retinal imaging

Optics Letters (2014)

Justo Arines Rene Hernandez Stefan Sinzinger Adrian Grewe Eva Acosta

We propose a hybrid optical-digital imaging system that can provide high-resolution retinal images without wavefront sensing or correction of the spatial and dynamic variations of eye aberrations. A methodology based on wavefront coding is implemented in a fundus camera in order to obtain a high-quality image of retinal detail. Wavefront-coded systems rely simply on the use of a cubic-phase plate in the pupil of the optical system. The phase element is intended to blur images in such a way that invariance to optical aberrations is achieved. The blur is then removed by image postprocessing. Thus, the system can provide high-resolution retinal images, avoiding all the optics needed to sense and correct ocular aberration, i.e., wavefront sensors and deformable mirrors.

Wavefront sensor

Deformable Mirror

10.1364/ol.39.003986

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Citations (20)

Optimized systems for energy efficient optical tweezing

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE (2013)

Ronald Kampmann Roman Kleindienst Adrian Grewe Elisabeth Bürger Andreas Oeder

Compared to conventional optics like singlet lenses or even microscope objectives advanced optical designs help to develop properties specifically useful for efficient optical tweezers. We present an optical setup providing a customized intensity distribution optimized with respect to large trapping forces. The optical design concept combines a refractive double axicon with a reflective parabolic focusing mirror. The axicon arrangement creates an annular field distribution and thus clears space for additional integrated observation optics in the center of the system. Finally the beam is focused to the desired intensity distribution by a parabolic ring mirror. The compact realization of the system potentially opens new fields of applications for optical tweezers such as in production industries and micro-nano assembly.

Axicon

Nonimaging optics

10.1117/12.2004287

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Citations (1)

Diffractive array optics tuned by rotation

Applied Optics (2016)

Adrian Grewe Patrick Feßer Stefan Sinzinger

In this work, we apply the Alvarez–Lohmann principle for varifocal lenses to diffractive off-axis elements tuned by rotation. Two methods to combine multiple elements into arrays are presented. Further, we show that inverse phase sections result from a 2π ambiguity of the rotation. Quantization techniques are applied to eliminate these unwanted sections. As proof of concept, a retrofocus lens using a tunable diffractive lens array is presented.

Optical Rotation

10.1364/ao.56.000a89

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Citations (24)

Spectral characteristics of chromatic confocal imaging systems

Applied Optics (2014)

Matthias Hillenbrand Beate Dr.-Ing. Mitschunas F.H.H. Brill Adrian Grewe Stefan Sinzinger

We present signal-generation models for chromatic confocal imaging systems with illumination and detection pinholes of finite size: a collinear model that considers neither aberrations nor diffraction effects, a geometrical model that accounts for aberrations, and a wave optical model covering both aberrations and diffraction effects. These models are aimed at describing the spectral response of multipoint sensor systems with field-dependent aberrations and vignetting effects. They are suitable for single- and double-pass systems with either diffusely or specularly reflecting surfaces under test. We show experimental results to verify our models.

Vignetting

Chromatic aberration

Ptychography

10.1364/ao.53.007634

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Citations (34)

Parallelized chromatic confocal systems enable efficient spectral information coding

SPIE Newsroom (2012)

Matthias Hillenbrand Adrian Grewe Stefan Sinzinger

Chromatic confocal imaging systems 1–3 are based on the well-known principle of confocal microscopy. 4 They use a polychromatic light source instead of a laser, and the focal length has strong wavelength dependence so that different wavelengths are focused at different axial distances. The wavelength dependence is achieved by replacing the standard objective lens with a hyperchromatic lens. 5, 6 Hyperchromatic systems are characterized by an optimized longitudinal chromatic aberration adapted to the specific application requirements. 7, 8

10.1117/2.1201301.004642

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Citations (2)

Hyper- and multispectral imaging systems - a survey of different approaches at the Ilmenau University of Technology

Shaping the Future by Engineering: Proceedings ; 58th IWK, Ilmenau Scientific Colloquium, Technische Universität Ilmenau, 8 - 12 September 2014 (2014)

Maik Rosenberger Martin Correns Richard Fütterer Gerhard Linß Eberhard Manske

Hyperspectral imaging technologies and multispectral imaging technologies became more and more important for industrial measurement techniques, quality control and automation technologies. One unsolved problem is the fast and simultaneous image capturing of different spectral channels. The best approach up-to-date is known as push-broom scanner. On the Ilme nau University of Technology different methodologies are objective of the recent research as well as for the research in the future. The paper gives a survey about the different approaches. The paper starts with a system which deals with the principle of FTIR Spectroscopy, which needs a mathematic transformation to deliver spectral image data. In the following two chapters a confocal approach using tunable optical elements based on Alvarez Lohmann lenses will be presented. The paper ends with a multispectral system operating with different color filters.

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