TY - JOUR A1 - Vollmer, Michael T1 - Gefrierende Gewässer JF - Physik in unserer Zeit KW - Gefrieren von Seen KW - Eiswachstumsmodell KW - Konvektion KW - Strahlung KW - Stefan-Boltzmann-Gesetz KW - Wärmeleitfähigkeit KW - optische Eisdickenmessung Y1 - 2021 U6 - https://doi.org/10.1002/piuz.202001589 VL - 52 IS - 1 SP - 19 EP - 25 PB - Wiley-Blackwell ER - TY - JOUR A1 - Vollmer, Michael A1 - Möllmann, Klaus-Peter T1 - Fata Morgana im Wasserbecken JF - Physik in unserer Zeit KW - Fata Morgana KW - Luftspiegelung Y1 - 2020 U6 - https://doi.org/10.1002/piuz.202001575 VL - 51 IS - 2 SP - 98 EP - 99 PB - Wiley-Blackwell ER - TY - CHAP A1 - Richards, A. A1 - Hübner, M. A1 - Vollmer, Michael ED - Holst, Gerald C. T1 - Measurements of SWIR backgrounds using the swux unit of measure T2 - Infrared Imaging Systems: Design, Analysis, Modeling, and Testing XXIX : 17-18 April 2018, Orlando, Florida, United States T3 - Proceedings of SPIE - 10625 KW - Short wave infrared radiation KW - Sensors KW - Light sources and illumination KW - Cameras KW - Sun KW - Calibration Y1 - 2018 U6 - https://doi.org/10.1117/12.2305282 PB - SPIE CY - Bellingham, Washington, USA ER - TY - JOUR A1 - Vollmer, Michael A1 - Mustard, Alexander T1 - Blue - the color of (pure) water JF - Physics Education N2 - Water can exhibit many different colors due to a variety of physical properties. Here, we focus on some observable colors within very pure freshwater. We only treat the absorption of light due to electronic and ro-vibrational excitations and scattering due to refractive index fluctuations of the water and the respective consequences for the appearance of colors. Y1 - 2019 UR - https://iopscience.iop.org/article/10.1088/1361-6552/ab130a U6 - https://doi.org/10.1088/1361-6552/ab130a SN - 0031-9120 (print) 1361-6552 (online) IS - Ausgabe: 4/ Band: 54 PB - IOP Publishing ER - TY - JOUR A1 - Vollmer, Michael T1 - The freezing of lakes in winter JF - European Journal of Physics N2 - Freezing of lakes is described using a simplified one-dimensional model, which gives ice thickness, ice growth rates, and ice surface temperature as a function of time. Model data for a specific lake with known meteorological conditions are compared to estimated ice thickness using a simple optical method. Finally, more advanced potential students projects are briefly discussed and results of a numerical solution are compared to the simplified model. Y1 - 2019 UR - https://iopscience.iop.org/article/10.1088/1361-6404/ab07f8 U6 - https://doi.org/10.1088/1361-6404/ab07f8 SN - 1367-2630 IS - Ausgabe: 3/ Band: 40 PB - IOP Publishing ER - TY - JOUR A1 - Vollmer, Michael T1 - Die Grenzen des Auges JF - Physik Journal N2 - Mithilfe geeigneter Hilfsmittel lassen sich die Wahrnehmungsgrenzen des Auges überwinden. Menschliche Augen weisen räumliche, zeitliche und spektrale Begrenzungen auf, welche die Wahrnehmung einschränken. Geeignete optische Geräte und Kameras helfen, diese zu überwinden und eine große Vielfalt an physikalischen Phänomenen für die Lehre zu erschließen. Die Angaben zu den Anteilen an aufgenommener Information durch die menschlichen Sinnesorgane schwanken meist zwischen etwa 81 und 87 Prozent für die Augen, 10 bis 11 Prozent für die Ohren und dem Rest für schmecken, riechen und tasten. Das Produktmarketing macht sich dies gezielt zunutze. Offensichtlich ist für alle subjektiven Wahrnehmungen unserer Umwelt das Auge sehr wichtig; in Bezug auf räumliche und zeitliche Auflösung sowie spektrale Empfindlichkeit ist es jedoch eingeschränkt. Die dadurch entstehenden Wahrnehmungsgrenzen für physikalische Vorgänge und Objekte lassen sich durch geeignete optische Geräte mit – das Auge ersetzenden – Sensoren in Kamerasystemen überwinden (Abb. 1). Dies erhöht die Zahl beobachtbarer technischer und natürlicher Phänomene und den daraus gewonnenen Informationsgehalt deutlich. Da entsprechende Kameras relativ preiswert sind und sich damit viele einfache Experimente erfolgreich demonstrieren lassen, kann ein gezielter Einsatz die Lehre der Physik an Schulen und in einführenden Vorlesungen an Hochschulen bereichern und den Einstieg in verwandte Gebiete wie die Infrarotastronomie vorbereiten. (...) Y1 - 2023 IS - 3 SP - 28 EP - 33 ER - TY - JOUR A1 - Vollmer, Michael T1 - The evolution of IR imaging: What’s next? JF - Laser Focus World Magazine N2 - The vast majority of all human sensory inputs occur through our eyes. Light from direct sources or scattered light from objects enters our eyes and is focused onto the retina. The resulting signals are interpreted by the brain, which leads to the perception of the image of the observed objects. Although quite efficient for our daily life, many technological applications require sensor properties beyond the characteristics of our eyes. A major limitation regarding microscopic objects is spatial resolution, which is overcome by microscopes. Time resolution can be dealt with using either time-lapse or high-speed cameras. Finally, eyes only detect visible radiation within the wavelength range from about 380 nm to 780 nm. Changing the detected spectral range of electromagnetic radiation can dramatically enhance our vision. Shorter wavelengths such as x-rays are valuable tools for medical imaging, while ultraviolet (UV) imaging is used for forensics. Longer-wavelength thermal radiation used for imaging is often defined within spectral ranges, characterized by the photoelectric detector materials used and the respective atmospheric windows. Y1 - 2022 UR - https://www.laserfocusworld.com/detectors-imaging/article/14233175/the-evolution-of-ir-imaging-whats-next SP - 23 EP - 26 PB - endeavor business media ER - TY - CHAP A1 - Vollmer, Michael ED - Haglund, Jesper ED - Jeppsson, Fredrik ED - Schönborn, Konrad J. T1 - Fundamentals of Thermal Imaging T2 - Thermal Cameras in Science Education N2 - The quantitative explanation of thermal radiation in 1900 by Max Planck started a development, which today has resulted in modern infrared technologies with thermal imaging cameras. The present work briefly describes the fundamentals of infrared imaging, based on the fact, that every object at a temperature T > 0 K emits thermal radiation. Its amount is only governed by temperature and the material quantity emissivity. Factors that define types and properties of commercial IR cameras, such as temperature range in nature and industry, the atmospheric windows for IR radiation as well as available optics and detectors are discussed. A short summary of typical specifications of IR cameras and interpretation of recorded images is given. Y1 - 2022 U6 - https://doi.org/10.1007/978-3-030-85288-7_2 SP - 7 EP - 25 PB - Springer CY - Cham ER - TY - CHAP A1 - Vollmer, Michael ED - Haglund, Jesper ED - Jeppsson, Fredrik ED - Schönborn, Konrad J. T1 - Infrared Cameras as Smartphone Accessory: Qualitative Visualization or Quantitative Measurement? T2 - Thermal Cameras in Science Education N2 - Recently, infrared cameras have become available as smartphone accessories. Being less expensive than regular infrared cameras they are readily affordable and widespread use in the future is expected. Available commercial models are compared and examples for meaningful use and interpretation of respective qualitative images is given. The respective arguments also directly apply to other commonly used low-grade IR cameras with similar pixel resolution and frame rates. It is assumed that users know about the typical problems due to, e.g., thermal reflections. Rather than discussing those, focus is on the danger of wrong interpretations, in particular with regard to the low frame rate, the often implemented image processing within the cameras, the imposed restrictions on necessary input parameters, and the extremely limited spatial resolution and respective errors in potential quantitative analyses. Y1 - 2022 U6 - https://doi.org/10.1007/978-3-030-85288-7_9 SP - 129 EP - 145 PB - Springer CY - Cham ER - TY - CHAP A1 - Vollmer, Michael ED - Gómez-López, Vicente M. ED - Bhat, Rajeev T1 - Physics of the Electromagnetic Spectrum T2 - Electromagnetic Technologies in Food Science N2 - Electromagnetic (EM) waves, spanning about 15 orders of magnitude of wavelength (or frequency or energy) from radio waves via microwaves, infrared radiation, visible light, ultraviolet radiation, and X-rays to the highly energetic γ-rays, are utilized in food processing. In order to explain all uses of these waves in the food industry, the chapter begins with a general discussion of properties of waves and their description with wavelength frequency, speed of propagation, and also energy transport. Using visible light as starting point, electromagnetic waves in other wavelength regimes are discussed. The interaction of EM radiation with matter reveals that the wave description alone is insufficient to explain all observed phenomena. Understanding the attenuation of EM radiation in matter requires knowledge of the particle properties of electromagnetic waves, most easily summarized by the concept of photons which carry energy as well as momentum. This wave–particle duality does apply not only to EM waves, i.e. photons, but also to the particles which build up matter, in particular electrons, which also need to be described as waves. This leads to respective quantum mechanical explanations of the microscopic structure of matter in the form of atoms, molecules, and nuclei. Knowledge of their structure is a prerequisite to understand, first, the generation of EM radiation and, second, also its interaction with matter. As a result, it will become obvious that there are mostly three different usages of EM radiation in the food industry: preserving, characterizing, and heating. Y1 - 2022 U6 - https://doi.org/10.1002/9781119759522.ch1 SP - 1 EP - 32 PB - Wiley CY - Chichester, UK ER -