Mr. Eugen Dumitrescu Profile

Eugen Dumitrescu

Managing Director at TRIOPTICS GmbH

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Publications (11)

Proceedings Article | 6 October 2017 Paper

MTF measurement of IR optics in different temperature ranges

Alexander Bai, Hannes Duncker, Eugen Dumitrescu

Proceedings Volume 10433, 104331D (2017) https://doi.org/10.1117/12.2275308

KEYWORDS: Modulation transfer functions, Temperature metrology, Thermography, Infrared imaging, Infrared sensors, Distortion, Optics manufacturing, Optical testing, Staring arrays, Mid-IR

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Proceedings Article | 18 June 2013 Paper

Precise opto-mechanical characterization of assembled infrared optics

Daniel Winters, Patrik Langehanenberg, Josef Heinisch, Eugen Dumitrescu

Proceedings Volume 8704, 87042D (2013) https://doi.org/10.1117/12.2015679

KEYWORDS: Lenses, Autocollimators, Interferometers, Silicon, Infrared imaging, Infrared lenses, Optics manufacturing, Long wavelength infrared, Error analysis, Reticles

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Proceedings Article | 24 October 2012 Paper

Automated optical testing of LWIR objective lenses using focal plane array sensors

Daniel Winters, Patrik Erichsen, Christian Domagalski, Frank Peter, Josef Heinisch, Eugen Dumitrescu

Proceedings Volume 8541, 854105 (2012) https://doi.org/10.1117/12.974957

KEYWORDS: Modulation transfer functions, Cameras, Long wavelength infrared, Infrared imaging, Thermography, Sensors, Staring arrays, Image quality, Imaging systems, Infrared cameras

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The image quality of today's state-of-the-art IR objective lenses is constantly improving while at the same time the market for thermography and vision grows strongly. Because of increasing demands on the quality of IR optics and increasing production volumes, the standards for image quality testing increase and tests need to be performed in shorter time. Most high-precision MTF testing equipment for the IR spectral bands in use today relies on the scanning slit method that scans a 1D detector over a pattern in the image generated by the lens under test, followed by image analysis to extract performance parameters. The disadvantages of this approach are that it is relatively slow, it requires highly trained operators for aligning the sample and the number of parameters that can be extracted is limited. In this paper we present lessons learned from the R and D process on using focal plane array (FPA) sensors for testing of long-wave IR (LWIR, 8-12 m) optics. Factors that need to be taken into account when switching from scanning slit to FPAs are e.g.: the thermal background from the environment, the low scene contrast in the LWIR, the need for advanced image processing algorithms to pre-process camera images for analysis and camera artifacts. Finally, we discuss 2 measurement systems for LWIR lens characterization that we recently developed with different target applications: 1) A fully automated system suitable for production testing and metrology that uses uncooled microbolometer cameras to automatically measure MTF (on-axis and at several o-axis positions) and parameters like EFL, FFL, autofocus curves, image plane tilt, etc. for LWIR objectives with an EFL between 1 and 12mm. The measurement cycle time for one sample is typically between 6 and 8s. 2) A high-precision research-grade system using again an uncooled LWIR camera as detector, that is very simple to align and operate. A wide range of lens parameters (MTF, EFL, astigmatism, distortion, etc.) can be easily and accurately measured with this system.

Proceedings Article | 15 February 2012 Paper

High precision geometrical characterization and alignment of miniaturized optics

Patrik Langehanenberg, Josef Heinisch, Eugen Dumitrescu

Proceedings Volume 8249, 82490U (2012) https://doi.org/10.1117/12.908727

KEYWORDS: Lenses, Autocollimators, Optical components, Distance measurement, Optical alignment, Interferometers, Geometrical optics, Mirrors, Optics manufacturing, Cements

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Proceedings Article | 15 February 2011 Paper

Automated measurement of centering errors and relative surface distances for the optimized assembly of micro-optics

Patrik Langehanenberg, Eugen Dumitrescu, Josef Heinisch, Stefan Krey, Aiko Ruprecht

Proceedings Volume 7926, 79260E (2011) https://doi.org/10.1117/12.874628

KEYWORDS: Interferometers, Imaging systems, Autocollimators, Error analysis, Objectives, Optical components, Cell phones, Optical alignment, Optics manufacturing, Refractive index

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Proceedings Article | 29 August 2008 Paper

High resolution wavefront measurement of aspheric optics

I. Erichsen, S. Krey, J. Heinisch, A. Ruprecht, E. Dumitrescu

Proceedings Volume 7060, 70600T (2008) https://doi.org/10.1117/12.794467

KEYWORDS: Wavefronts, Semiconducting wafers, Wavefront sensors, Sensors, Light sources, Optical testing, Modulation transfer functions, Wafer-level optics, Aspheric optics, Aspheric lenses

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Proceedings Article | 14 May 2007 Paper

Automatic centring and bonding of lenses

Stefan Krey, J. Heinisch, E. Dumitrescu

Proceedings Volume 10316, 1031611 (2007) https://doi.org/10.1117/12.719838

KEYWORDS: Lenses, Telescopes, Ultraviolet radiation, Autocollimation, Tolerancing, Error analysis, Reticles, Manufacturing, Objectives, Optical alignment

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Proceedings Article | 14 May 2007 Paper

Highest precision centering error measurement

J. Heinisch, E. Dumitrescu, S. Krey

Proceedings Volume 10316, 1031610 (2007) https://doi.org/10.1117/12.719697

KEYWORDS: Objectives, Lenses, Optical components, Autocollimators, Optics manufacturing, Precision measurement, Error analysis, Optical imaging, Optical alignment

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Proceedings Article | 14 May 2007 Paper

Real-time MTF measurement of CMOS and CCD cameras

J. Heinisch, E. Dumitrescu, S. Krey

Proceedings Volume 10316, 103160Y (2007) https://doi.org/10.1117/12.719656

KEYWORDS: Modulation transfer functions, Cameras, Sensors, CCD cameras, CCD image sensors, Imaging systems, Software development, CMOS sensors, Image analysis, Standards development

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Proceedings Article | 1 September 2006 Paper

Novel technique for measurement of centration errors of complex completely mounted multi-element objective lenses

J. Heinisch, E. Dumitrescu, S. Krey

Proceedings Volume 6288, 628810 (2006) https://doi.org/10.1117/12.693356

KEYWORDS: Lenses, Objectives, Autocollimators, Cell phones, Digital cameras, Optical components, Optical spheres, Cameras, Measurement devices, Optical testing

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Proceedings Article | 11 November 2002 Paper

Novel concept for the ultraprecise and fast measurement of the nanotopography of large wafers

Ingolf Weingaertner, Matthias Wurm, Ralf Geckeler, Clemens Elster, Michael Schulz, Eugen Dumitrescu, Stefan Krey, Josef Heinisch

Proceedings Volume 4779, (2002) https://doi.org/10.1117/12.451713

KEYWORDS: Semiconducting wafers, Measurement devices, Spatial frequencies, Distance measurement, Interferometers, Reconstruction algorithms, Algorithm development, Sensors, Wafer-level optics, Deflectometry

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The measurement of the topography or the nanotopography of large wafers up to 450 mm in diameter with satisfactory lateral resolution and nanometer uncertainty is still an unsolved problem. The topography of wafers covers a relatively large measurement range as wafers have surfaces with a so-called "slightly unflat" topography which mostly exceeds the measurement capabilities of interferometers. For the ultraprecise and traceable measurement of the slope and topography of slightly unflat optical surfaces, a novel scanning deflectometry principle has been developed. An uncertainty of the topography in the nanometer range will be achieved, as this principle minimizes error influences and allows a highly precise calibration of the angle measuring device. The main goal is to use this principle for the ultraprecise measurement of the nanotopography of large wafers. The measurement principle is based on the analysis of differences of reflection angles obtained at surface points which are separated by large lateral shears. It does not rely on external reference surfaces of matched topography and in first and second order is independent of any stage errors and the whole-body motion of the specimen. The measurands are directly traced back to the base units of angle and length. The specific idea of wafer measurement is to combine rotational and linear scanning with the measurement of slope difference vectors and to arrive at an unambiguous solution for the topography and nanotopography. The equations with the slope difference vectors are solved to reconstruct the slope vectors, as newly developed mathematical algorithms allow the surface slope to be reconstructed from slope differences for two different shears. This is reached by applying natural extensions and shearing transfer functions by a mathematically exact method over the whole surface area. Further the differential equations for the slope vectors are solved to unambiguously reconstruct the topography. With this method it is possible to achieve nanometer uncertainty and at the same time a high lateral resolution, short measurement times and the possibility of mastering the large measurement range necessary for slightly unflat wafer surfaces.

Showing 5 of 11 publications

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