Mr. Christian Ulrich Profile

Christian Ulrich

at Fraunhofer-ICT

SPIE Involvement:

Author

Publications (5)

Proceedings Article | 20 June 2024 Presentation + Paper

Multiplexed dual-core QCL-based sensor for real-time standoff-spectroscopy in crime scene investigations

Marko Haertelt, Yuri Flores, Markus Schwarzenberg, Andre Merten, Christian Ulrich, Frank Schnürer

Proceedings Volume 12999, 129990K (2024) https://doi.org/10.1117/12.3022543

KEYWORDS: Sensors, Quantum cascade lasers, Microopto electromechanical systems, Backscatter, Multiplexing, Explosives, Infrared sensors, Forensic science, Biological samples, Spectroscopy

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Proceedings Article | 7 June 2024 Presentation + Paper

Laser-based infrared sensor for fast and non-contact detection and identification of forensic traces in crime scene investigations

Marko Haertelt, Yuri Flores, Christian Ulrich, Frank Schnürer

Proceedings Volume 13056, 1305605 (2024) https://doi.org/10.1117/12.3014160

KEYWORDS: Quantum cascade lasers, Forensic science, Explosives, Microopto electromechanical systems, Biological samples, Infrared sensors, Sensors, Semiconductor lasers

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Proceedings Article | 12 September 2021 Poster + Paper

Final results of NATO SET-237 "Printed Standards for Stand-off Detection“ and future developments

F. Schnürer, C. Ulrich, R. Chirico, R. Moon, J. Guicheteau, K. Hung

Proceedings Volume 11869, 118690M (2021) https://doi.org/10.1117/12.2599274

KEYWORDS: Particles, Printing, Standards development, Explosives, Image processing, Statistical analysis, Sensors, Printed circuit board testing, Photomicroscopy, Inkjet technology

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The North Atlantic Treaty Organization (NATO) SET-237 Task Group (TG) was formed in January 2016 to develop and recommend to NATO a reference standard methodology (or methodologies) for fabricating quantifiable surface standards for the evaluation of stand-off active and passive optical systems. The purpose of this task group, which was led by the DEVCOM-Chemical Biological Center, was to utilise different printing technologies to produce explosives test standards for the evaluation of effective standoff threat detection capabilities for force protection, IED detection and threat diagnostics. The TG also developed the procedures to characterize the samples (crystalline phase of material, morphology) and to estimate accuracy and precision information like surface coverage, particle size distribution, areal density, etc. of the prepared samples. Fraunhofer ICT was one of the organizations fabricating quantifiable surface standards using a Nanoplotter NP 2.1 from GeSim GmbH, Germany, a piezo-based drop on demand printer. In collaboration with DEVCOM-CBC, Fraunhofer ICT and ENEA, an ImageJ Standard Operating Procedures (SOP) for calculating particle statistics was established. ENEA acted as an “independent laboratory” characterising the coupons produced by the other partners to develop standard protocols to be included in the certificate of analysis of the coupons produced with ink-jet printers. A NATO field trial was organised by ENEA at its test site in Frascati (Rome) in 2019 to assess the printed samples against multiple field instruments for the test standard’s ability to meet the NATO SET-237 mission requirements. The poster will present samples prepared with Inkjet printer as well as protocols for their evaluation together with a new plug-in for the software ImageJ to process micrographs of the samples. The results of the work done in this TG will be utilised to support the work within the NATO-SPS project DEXTER and the EU Horizon 2020 project RISEN.

Proceedings Article | 7 October 2019 Paper

Standardized characterization of inkjet-printed explosive trace samples

Frank Schnürer, Christian Ulrich, Roberto Chirico, Stefano Di Frischia, Raphael Moon, Kevin Hung

Proceedings Volume 11166, 111660W (2019) https://doi.org/10.1117/12.2533029

KEYWORDS: Particles, Image processing, Explosives, Printing, Standards development, Image segmentation, Statistical analysis, Inkjet technology, Microscopes, Image quality

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Detection systems for explosives have to be tested and validated with realistic samples. However, at present, well defined and characterized and homogeneous test materials for the development and validation of trace detection systems are still missing. Drop-on-demand and inkjet printing technology has become a promising method of producing standardized chemically contaminated test materials with high precision, accuracy, scalability, and flexibility to allow for the inexpensive, high throughput production. Especially for the preparation of samples for optical stand-off technologies the drop-on-demand technique leads to samples of higher quality. Test samples with contaminations ranging from nanograms to micrograms have been prepared and analysed over several weeks of storage. The influence of plot parameters on the morphology and durability of printed samples of various common explosives have been investigated on different substrates. Our results show that this technique leads to samples of higher quality compared to already existing preparation methods of reference samples. For the evaluation of deposition uniformity, quantity and reproducibility samples on several different surfaces, with different solvents and areal density distributions were prepared and analysed. HPLC measurements were used to quantitatively evaluate the durability of printed samples. The morphology of the test samples has been characterized by optical microscopy and confocal Raman-microscopy. This poster focuses on the development of a proposed standardized methodology for the characterization of particulate trace explosive samples of all types. Micrographs were processed with ImageJ (National Institutes of Health), an open source image processing program designed for scientific multidimensional images, which has already been applied to the shape analysis of particles in various research areas and for different materials. The main problem is to find the right threshold to apply to segment the image into features of interest (particles) and background. It is certainly a goal of digital image processing to establish protocols that eliminate variability, but currently it is not possible to use only one threshold with a fixed value for a set of images of samples of various explosives. Manual methods have several limitations like reduced reproducibility, high user bias, tedious and time-consuming fiddling-around finding an "appropriate" cut-off value, etc. The open source software that is in use to process the images provides several methods to automatically apply a threshold. Based on the morphology of the particles and the applied threshold, the obtained results can be really different and, an incorrect selection of the automatic threshold could provide either an overestimation or an underestimation of the parameters to be evaluated, particle size distribution and area coverage.

Proceedings Article | 8 October 2018 Paper

Printed explosives standards for the evaluation of stand-off optical systems

Frank Schnürer, Christian Ulrich, Stefan Müller, Wenka Schweikert

Proceedings Volume 10802, 108020V (2018) https://doi.org/10.1117/12.2325305

KEYWORDS: Printing, Explosives, Inkjet technology, Standards development, Particles, Explosives detection, Statistical analysis

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