@article{VollmerMoellmann2019, author = {Vollmer, Michael and M{\"o}llmann, Klaus-Peter}, title = {Manche m{\"o}gen's kochend heiß}, series = {Physik in unserer Zeit}, volume = {50}, journal = {Physik in unserer Zeit}, number = {1}, publisher = {Wiley-VCH}, doi = {10.1002/piuz.201901533}, pages = {46 -- 47}, year = {2019}, language = {de} } @book{Vollmer2019, author = {Vollmer, Michael}, title = {Atmosph{\"a}rische Optik f{\"u}r Einsteiger, Lichtspiele in der Luft}, publisher = {Springer Spektrum}, address = {Berlin / Heidelberg}, isbn = {978-3-662-58362-3}, doi = {10.1007/978-3-662-58362-3}, publisher = {Technische Hochschule Brandenburg}, pages = {377}, year = {2019}, language = {de} } @article{VollmerMoellmann2018, author = {Vollmer, Michael and M{\"o}llmann, Klaus-Peter}, title = {Die Qual der Wahl an Weihnachten}, series = {Physik in unserer Zeit}, volume = {49}, journal = {Physik in unserer Zeit}, number = {6}, doi = {10.1002/piuz.201801528}, pages = {306 -- 306}, year = {2018}, language = {de} } @article{VollmerMoellmann2018, author = {Vollmer, Michael and M{\"o}llmann, Klaus-Peter}, title = {Infrared cameras as accessories to smartphones: facts you need to know}, series = {Physics Education}, volume = {53}, journal = {Physics Education}, number = {6}, doi = {10.1088/1361-6552/aae277}, pages = {065019 -- 065019}, year = {2018}, language = {en} } @article{VollmerMoellmann2018, author = {Vollmer, Michael and M{\"o}llmann, Klaus-Peter}, title = {Und sie dreht sich doch …}, series = {Physik in unserer Zeit}, volume = {49}, journal = {Physik in unserer Zeit}, number = {5}, doi = {10.1002/piuz.201801525}, pages = {254 -- 254}, year = {2018}, language = {de} } @article{VollmerMoellmann2018, author = {Vollmer, Michael and M{\"o}llmann, Klaus-Peter}, title = {Slow Speed - Fast Motion. Funktion und Technik von Zeitrafferkameras}, series = {Physik in unserer Zeit}, volume = {49}, journal = {Physik in unserer Zeit}, number = {4}, doi = {10.1002/piuz.201801507}, pages = {190 -- 193}, year = {2018}, language = {de} } @article{VollmerMoellmann2018, author = {Vollmer, Michael and M{\"o}llmann, Klaus-Peter}, title = {Von Eisw{\"u}rfeln und gefrorenen Seen}, series = {Physik in unserer Zeit}, volume = {49}, journal = {Physik in unserer Zeit}, number = {4}, doi = {10.1002/piuz.201801518}, pages = {201 -- 202}, year = {2018}, language = {de} } @article{VollmerMoellmann2018, author = {Vollmer, Michael and M{\"o}llmann, Klaus-Peter}, title = {Direct speed of sound measurement within the atmosphere during a national holiday in New Zealand}, series = {Physics Education}, volume = {53}, journal = {Physics Education}, number = {3}, doi = {10.1088/1361-6552/aab6ce}, pages = {033007 -- 033007}, year = {2018}, language = {de} } @article{VollmerMoellmann2018, author = {Vollmer, Michael and M{\"o}llmann, Klaus-Peter}, title = {Time-lapse videos for physics education: specific examples}, series = {Physics Education}, volume = {53}, journal = {Physics Education}, number = {3}, doi = {10.1088/1361-6552/aab6cf}, pages = {033007 -- 033007}, year = {2018}, language = {en} } @article{VollmerShawNugentetal.2019, author = {Vollmer, Michael and Shaw, Joseph A. and Nugent, Paul and Harris, Wilson}, title = {Heiße Quellen im W{\"a}rmebild. Yellowstone-Park im Infraroten}, series = {Physik in unserer Zeit}, volume = {50}, journal = {Physik in unserer Zeit}, number = {5}, publisher = {Wiley-VCH}, doi = {10.1002/piuz.201901539}, pages = {244 -- 250}, year = {2019}, language = {de} } @article{VollmerMoellmann2019, author = {Vollmer, Michael and M{\"o}llmann, Klaus-Peter}, title = {Alles kalter Kaffee? Rasante Physik}, series = {Physik in unserer Zeit}, volume = {50}, journal = {Physik in unserer Zeit}, number = {5}, publisher = {Wiley-VCH}, doi = {10.1002/piuz.201901553}, pages = {252 -- 253}, year = {2019}, language = {de} } @inproceedings{VollmerShaw2019, author = {Vollmer, Michael and Shaw, Joseph A.}, title = {Near infrared photography of atmospheric optical phenomena}, series = {Fifteenth Conference on Education and Training in Optics and Photonics: ETOP 2019}, booktitle = {Fifteenth Conference on Education and Training in Optics and Photonics: ETOP 2019}, address = {Quebec City, Quebec, Canada}, doi = {10.1117/12.2523165}, pages = {111431P-1 -- 111431P-6}, year = {2019}, language = {en} } @inproceedings{VollmerShaw2019, author = {Vollmer, Michael and Shaw, Joseph A.}, title = {Extended visual range: an observation during a total solar eclipse}, series = {Fifteenth Conference on Education and Training in Optics and Photonics: ETOP 2019}, booktitle = {Fifteenth Conference on Education and Training in Optics and Photonics: ETOP 2019}, address = {Quebec City, Quebec, Canada}, doi = {10.1117/12.2523167}, pages = {111431Q-1 -- 111431Q-6}, year = {2019}, language = {en} } @article{VollmerMoellmann2018, author = {Vollmer, Michael and M{\"o}llmann, Klaus-Peter}, title = {Slow speed—fast motion: time-lapse recordings in physics education}, series = {Physics Education}, volume = {53}, journal = {Physics Education}, number = {3}, doi = {10.1088/1361-6552/aaa954}, pages = {035019 -- 035019}, year = {2018}, language = {en} } @article{MoellmannRegehlyVollmer2020, author = {M{\"o}llmann, Klaus-Peter and Regehly, Martin and Vollmer, Michael}, title = {Spectroscopy and microscopy analysis of semiconductor lasers in student laboratories}, series = {European Journal of Physics}, volume = {41}, journal = {European Journal of Physics}, number = {2}, publisher = {Institute of Physics Publishing (IOP); European Physical Society}, doi = {10.1088/1361-6404/ab5075}, pages = {025302}, year = {2020}, language = {en} } @article{VollmerShaw2018, author = {Vollmer, Michael and Shaw, Joseph A.}, title = {Extended visual range during solar eclipses}, series = {Applied Optics}, volume = {57}, journal = {Applied Optics}, number = {12}, doi = {10.1364/AO.57.003250}, pages = {3250 -- 3259}, year = {2018}, language = {en} } @article{Vollmer2009, author = {Vollmer, Michael}, title = {Asymmetrische Polarlichter}, series = {Physik in unserer Zeit}, volume = {40}, journal = {Physik in unserer Zeit}, number = {6}, doi = {10.1002/piuz.200990107}, pages = {275 -- 275}, year = {2009}, language = {de} } @article{VollmerMoellmann2020, author = {Vollmer, Michael and M{\"o}llmann, Klaus-Peter}, title = {Unsichtbares sichtbar gemacht: Infrarotkameras f{\"u}r Smartphones}, series = {Physik in unserer Zeit}, volume = {51}, journal = {Physik in unserer Zeit}, number = {1}, publisher = {Wiley-VCH}, doi = {https://doi.org/10.1002/piuz.201901551}, pages = {29 -- 35}, year = {2020}, language = {de} } @article{VollmerMoellmann2020, author = {Vollmer, Michael and M{\"o}llmann, Klaus-Peter}, title = {Wenn Licht die Biege macht}, series = {Physik in unserer Zeit}, volume = {51}, journal = {Physik in unserer Zeit}, number = {1}, publisher = {Wiley-VCH}, doi = {https://doi.org/10.1002/piuz.202001569}, pages = {46 -- 47}, year = {2020}, language = {de} } @article{Vollmer2021, author = {Vollmer, Michael}, title = {Gefrierende Gew{\"a}sser}, series = {Physik in unserer Zeit}, volume = {52}, journal = {Physik in unserer Zeit}, number = {1}, publisher = {Wiley-Blackwell}, doi = {10.1002/piuz.202001589}, pages = {19 -- 25}, year = {2021}, language = {de} } @article{VollmerMoellmann2020, author = {Vollmer, Michael and M{\"o}llmann, Klaus-Peter}, title = {Fata Morgana im Wasserbecken}, series = {Physik in unserer Zeit}, volume = {51}, journal = {Physik in unserer Zeit}, number = {2}, publisher = {Wiley-Blackwell}, doi = {10.1002/piuz.202001575}, pages = {98 -- 99}, year = {2020}, language = {de} } @inproceedings{RichardsHuebnerVollmer2018, author = {Richards, A. and H{\"u}bner, M. and Vollmer, Michael}, title = {Measurements of SWIR backgrounds using the swux unit of measure}, series = {Infrared Imaging Systems: Design, Analysis, Modeling, and Testing XXIX : 17-18 April 2018, Orlando, Florida, United States}, booktitle = {Infrared Imaging Systems: Design, Analysis, Modeling, and Testing XXIX : 17-18 April 2018, Orlando, Florida, United States}, editor = {Holst, Gerald C.}, publisher = {SPIE}, address = {Bellingham, Washington, USA}, doi = {10.1117/12.2305282}, year = {2018}, language = {en} } @article{VollmerMustard2019, author = {Vollmer, Michael and Mustard, Alexander}, title = {Blue - the color of (pure) water}, series = {Physics Education}, journal = {Physics Education}, number = {Ausgabe: 4/ Band: 54}, publisher = {IOP Publishing}, issn = {0031-9120 (print) 1361-6552 (online)}, doi = {10.1088/1361-6552/ab130a}, year = {2019}, abstract = {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.}, language = {en} } @article{Vollmer2019, author = {Vollmer, Michael}, title = {The freezing of lakes in winter}, series = {European Journal of Physics}, journal = {European Journal of Physics}, number = {Ausgabe: 3/ Band: 40}, publisher = {IOP Publishing}, issn = {1367-2630}, doi = {10.1088/1361-6404/ab07f8}, year = {2019}, abstract = {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.}, language = {en} } @article{Vollmer2023, author = {Vollmer, Michael}, title = {Die Grenzen des Auges}, series = {Physik Journal}, journal = {Physik Journal}, number = {3}, pages = {28 -- 33}, year = {2023}, abstract = {Mithilfe geeigneter Hilfsmittel lassen sich die Wahrnehmungsgrenzen des Auges {\"u}berwinden. Menschliche Augen weisen r{\"a}umliche, zeitliche und spektrale Begrenzungen auf, welche die Wahrnehmung einschr{\"a}nken. Geeignete optische Ger{\"a}te und Kameras helfen, diese zu {\"u}berwinden und eine große Vielfalt an physikalischen Ph{\"a}nomenen f{\"u}r die Lehre zu erschließen. Die Angaben zu den Anteilen an aufgenommener Information durch die menschlichen Sinnesorgane schwanken meist zwischen etwa 81 und 87 Prozent f{\"u}r die Augen, 10 bis 11 Prozent f{\"u}r die Ohren und dem Rest f{\"u}r schmecken, riechen und tasten. Das Produktmarketing macht sich dies gezielt zunutze. Offensichtlich ist f{\"u}r alle subjektiven Wahrnehmungen unserer Umwelt das Auge sehr wichtig; in Bezug auf r{\"a}umliche und zeitliche Aufl{\"o}sung sowie spektrale Empfindlichkeit ist es jedoch eingeschr{\"a}nkt. Die dadurch entstehenden Wahrnehmungsgrenzen f{\"u}r physikalische Vorg{\"a}nge und Objekte lassen sich durch geeignete optische Ger{\"a}te mit - das Auge ersetzenden - Sensoren in Kamerasystemen {\"u}berwinden (Abb. 1). Dies erh{\"o}ht die Zahl beobachtbarer technischer und nat{\"u}rlicher Ph{\"a}nomene 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 einf{\"u}hrenden Vorlesungen an Hochschulen bereichern und den Einstieg in verwandte Gebiete wie die Infrarotastronomie vorbereiten. (...)}, language = {de} } @article{Vollmer2022, author = {Vollmer, Michael}, title = {The evolution of IR imaging: What's next?}, series = {Laser Focus World Magazine}, journal = {Laser Focus World Magazine}, publisher = {endeavor business media}, pages = {23 -- 26}, year = {2022}, abstract = {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.}, language = {de} } @incollection{Vollmer2022, author = {Vollmer, Michael}, title = {Fundamentals of Thermal Imaging}, series = {Thermal Cameras in Science Education}, booktitle = {Thermal Cameras in Science Education}, editor = {Haglund, Jesper and Jeppsson, Fredrik and Sch{\"o}nborn, Konrad J.}, publisher = {Springer}, address = {Cham}, doi = {10.1007/978-3-030-85288-7_2}, pages = {7 -- 25}, year = {2022}, abstract = {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.}, language = {en} } @incollection{Vollmer2022, author = {Vollmer, Michael}, title = {Infrared Cameras as Smartphone Accessory: Qualitative Visualization or Quantitative Measurement?}, series = {Thermal Cameras in Science Education}, booktitle = {Thermal Cameras in Science Education}, editor = {Haglund, Jesper and Jeppsson, Fredrik and Sch{\"o}nborn, Konrad J.}, publisher = {Springer}, address = {Cham}, doi = {10.1007/978-3-030-85288-7_9}, pages = {129 -- 145}, year = {2022}, abstract = {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.}, language = {en} } @incollection{Vollmer2022, author = {Vollmer, Michael}, title = {Physics of the Electromagnetic Spectrum}, series = {Electromagnetic Technologies in Food Science}, booktitle = {Electromagnetic Technologies in Food Science}, editor = {G{\´o}mez-L{\´o}pez, Vicente M. and Bhat, Rajeev}, publisher = {Wiley}, address = {Chichester, UK}, doi = {10.1002/9781119759522.ch1}, pages = {1 -- 32}, year = {2022}, abstract = {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.}, language = {en} } @article{Vollmer2023, author = {Vollmer, Michael}, title = {So weit das Auge tr{\"a}gt}, series = {Physik in unserer Zeit}, volume = {54}, journal = {Physik in unserer Zeit}, number = {5}, publisher = {Wiley}, issn = {1521-3943}, doi = {10.1002/piuz.202301675}, pages = {222 -- 230}, year = {2023}, abstract = {Sichtweiten in der Atmosph{\"a}re reichen von wenigen Metern im Nebel bis zu einigen hundert Kilometern bei extrem guten Fernsichtbedingungen. Die zugrundeliegende Physik geht vom Wahrnehmungskontrast aus. Dieser {\"a}ndert sich mit der Entfernung entlang der Sichtlinie zwischen Objekt und Auge aufgrund von Lichtstreuung und Absorption an den Bestandteilen der Atmosph{\"a}re. Dazu kommt bei der Fernsicht die Refraktion, die es erlaubt, auch {\"u}ber den durch die Kugelform der Erde geometrisch bedingten Horizont hinaus zu sehen.}, language = {de} } @article{VollmerEberhardt2024, author = {Vollmer, Michael and Eberhardt, Wolfgang}, title = {Ein einfaches Modell f{\"u}r die Vorhersage von CO2 Konzentrationen in der Atmosph{\"a}re in Abh{\"a}ngigkeit von globalen CO2 Emissionen}, series = {PhyDid B, Didaktik der Physik, Beitr{\"a}ge zur DPG-Fr{\"u}hjahrstagung}, volume = {1}, journal = {PhyDid B, Didaktik der Physik, Beitr{\"a}ge zur DPG-Fr{\"u}hjahrstagung}, number = {1}, publisher = {FU Berlin}, organization = {Fachverband Didaktik der Physik}, issn = {2191-379X}, pages = {379 -- 388}, year = {2024}, abstract = {Es wird das vielleicht einfachst m{\"o}gliche Modell vorgestellt, mit dem zeitabh{\"a}ngige CO2 Konzent-rationen c(t) in der Atmosph{\"a}re ausgehend von verschiedenen globalen Emissionsszenarien f{\"u}r CO2berechnet werden. Dazu wird eine einzelne inhomogene lineare Differenzialgleichung 1. Ordnung hergeleitet, deren Parameter sich aus den quantitativen Daten des global carbon project sowie Mauna Loa Daten f{\"u}r CO2 Konzentrationen errechnen. Das Modell wird erstens getestet am Zeitraum 1960 bis 2020 mit vergleichsweise guter quantitativer {\"U}bereinstimmung zu Messdaten. Zweitens wird f{\"u}r zwei typische IPCC Emissions-Szenarien ein Vergleich der Modellvorhersagen mit denen der kom-plexen IPCC Earth-System-Klimamodelle diskutiert mit qualitativer {\"U}bereinstimmung des zeitli-chen Verlaufs. Drittens werden Ergebnisse einiger ausgew{\"a}hlter neuer Emissionsszenarien pr{\"a}sen-tiert. Ungeachtet einiger Abweichungen zu komplexeren Klimamodellen zeichnet sich unser Mo-dell durch zwei wichtige Vorteile f{\"u}r die Lehre aus. Zum einen ist es sehr einfach f{\"u}r Studierende und begabte Sch{\"u}ler nutzbar, da die erforderliche L{\"o}sung der Differentialgleichung bereits mit han-dels{\"u}blicher Tabellenkalkulationssoftware wie z.B. Excel programmiert werden kann. Dadurch ge-stattet es zum anderen auch sehr einfach, den zeitlichen Verlauf von Emissionsszenarien zu ver{\"a}n-dern und innerhalb weniger Sekunden Ver{\"a}nderungen aufgrund ge{\"a}nderter Eingaben zu berechnen. Insofern eignet sich das Modell sehr gut als Einstieg in das Thema Klimamodellierung in einf{\"u}hren-den Hochschulvorlesungen zum Themenbereich Kohlenstoffkreislauf und Klimawandel. In der Schule kann es gegen Ende der Sekundarstufe 2 beispielsweise im Projektunterricht zum Themen-komplex Nachhaltigkeit in Physik und/oder Mathematik eingesetzt werden}, language = {de} } @article{VollmerEberhardt2024, author = {Vollmer, Michael and Eberhardt, Wolfgang}, title = {A simple model for the prediction of CO2 concentrations in the atmosphere, depending on global CO2 emissions}, series = {European Journal of Physics}, volume = {45}, journal = {European Journal of Physics}, number = {2}, doi = {10.1088/1361-6404/ad230d}, year = {2024}, abstract = {We present a very simple model for estimating time dependent atmospheric CO2 concentrations c(t) from global carbon emission scenarios, serving as single input data. We derive a single linear differential equation of 1st order, based on parameters which are estimated from quantitative data of the global carbon project and Mauna Loa data for CO2 concentrations. The model is tested first by comparing it to the 1960-2021 period with reasonably good quantitative agreement and, second to two of the typical current IPCC scenarios with good qualitative agreement. Finally, some new emission scenarios are modelled. Despite several drawbacks concerning absolute quantitative predictions, there are two important advantages of the model. First, it can be easily executed by students already with simple programmable spreadsheet programs such as Excel. Second input emission scenarios can be changed easily and expected changes are immediately seen for discussion during undergraduate and graduate courses on the carbon cycle and climate change.}, language = {en} } @article{Vollmer2024, author = {Vollmer, Michael}, title = {Limitations of the eye and how to overcome them}, series = {Journal of Physics: Conference Series}, volume = {2750}, journal = {Journal of Physics: Conference Series}, number = {1}, doi = {10.1088/1742-6596/2750/1/012001}, pages = {1 -- 10}, year = {2024}, abstract = {Human eyes have spatial, temporal, and spectral limitations which impose constraints on our perception. With appropriate optical devices and cameras, the limitations can be easily overcome. As a consequence, a huge variety of physical phenomena can be made accessible for teaching.}, language = {en} } @article{Vollmer2025, author = {Vollmer, Michael}, title = {Nachtsicht ins All mit dem bloßen Auge: Sag mir, wie weit die Sterne steh'n}, series = {Physik in unserer Zeit}, volume = {2025}, journal = {Physik in unserer Zeit}, publisher = {Wiley}, doi = {10.1002/piuz.202501751}, pages = {2 -- 10}, year = {2025}, language = {de} } @article{Vollmer2025, author = {Vollmer, Michael}, title = {Naked eye celestial objects and phenomena: how far can we see at night?}, series = {European Journal of Physics}, volume = {46}, journal = {European Journal of Physics}, number = {3}, publisher = {IOP Science}, doi = {10.1088/1361-6404/adbf74}, pages = {18}, year = {2025}, abstract = {How far can we see with the naked eye at night? Many celestial objects like stars and galaxies as well as transient phenomena such as comets and supernovae can be observed in the night sky. We discuss the furthest distances of such objects and phenomena observable with the naked eye during the night-time for Earth-bound observers. The physics of night-time visual ranges differs from that of daytime observations because human vision shifts from cones to rods. In addition, mostly point sources are observed due to the large distances involved. Whether celestial objects and phenomena can be detected depends on the contrast of their radiation and the background sky luminance. We present a concise overview of how far we can see at night by first discussing the effects of the Earth's atmosphere. This includes attenuation of transmitted radiation as well as its role as a source of background radiation. Disregarding the attenuation of light due to interstellar and intergalactic dust, simple maximum night-time visual range estimates are based on the inverse square law, which can be easily verified by laboratory and demonstration experiments. From the respective calculations, we find that individual stars within the Milky Way galaxy of up to 15 000 light years are observable. Even further away are observable galaxies with several billion stars. The Andromeda galaxy can be observed with the naked eye at a distance of around 2.5 million light years. Similarly, the observability of supernovae also allows a visual range beyond the Milky Way galaxy. Finally, gamma ray bursts as the most energetic events in the universe are discussed concerning naked eye observations.}, language = {en} } @article{Vollmer2025, author = {Vollmer, Michael}, title = {How far can we see at day?}, series = {European Journal of Physics}, volume = {46}, journal = {European Journal of Physics}, number = {3}, publisher = {IOP Science}, doi = {10.1088/1361-6404/adc4a0}, pages = {17}, year = {2025}, abstract = {We discuss the farthest objects on Earth observable for the unaided, healthy naked eye during the daytime, i.e., the maximum visual range for observers on Earth. Visual range depends first on the properties of the material between observer and object and its interaction processes with radiation, but second also on our visual perception system. After a rough comparison of ranges in water, glass, and the atmosphere, we focus on the physical basis of visual range for the latter. As a contrast phenomenon, visual range refers to allowed light paths within the atmosphere. It results from the interplay of geometry, refraction, and light scattering. We present a concise overview of this field by qualitative descriptions and quantitative estimates as well as classroom demonstration experiments. The starting point is the common geometrical visual ranges, followed by extensions due to refraction and limitations due to contrast, which depend on scattering and absorption processes within the atmosphere. The quantitative discussion of scattering is very helpful to easily understand the huge ranges in nature from meters in dense fog to hundreds of kilometers in clear atmospheres. Extreme visual ranges from about 300 km to above 500 km require optimal atmospheric conditions, cleverly chosen locations and times, and a sophisticated topography analysis. Even longer visual ranges are possible when looking through the vertical atmosphere. From the ISS, daytime ranges well above 1000 km are possible.}, language = {en} } @article{Vollmer2026, author = {Vollmer, Michael}, title = {How many stars appear colored to the naked eye?}, series = {Applied Optics}, volume = {65}, journal = {Applied Optics}, number = {9}, publisher = {Optica Publishing Group}, doi = {10.1364/AO.580635}, pages = {C27 -- C37}, year = {2026}, abstract = {Naked eye studies of the clear night sky reveal that a certain percentage of all observable stars can be perceived as having color. Subjective estimates differ widely, ranging from just a few to a maximum of above two hundred. Explanations are based on the emission spectra of the stars, which are modified by interstellar dust clouds, the Earth atmosphere, and mostly the inverse square law. Color changes occur not only for variation of the star's angular elevation above the horizon, but as well for decreasing nighttime sky brightness due to the transition from photopic via mesopic to scotopic vision. The maximum number of stars showing color to the naked eye depends on star illuminances on Earth and the background sky luminance. The limit of observing color is found to correspond to apparent visual magnitudes around , defining the number of colored stars. This also means that naked eye perception of stars with color is only possible for a certain star distance range, which is well below the maximum naked eye visual range of stars.}, language = {en} } @incollection{Vollmer2025, author = {Vollmer, Michael}, title = {Elektromagnetische Wellen - Grundlagen und ausgew{\"a}hlte Anwendungen}, series = {Schwingungen und Wellen in Alltagskontexten}, booktitle = {Schwingungen und Wellen in Alltagskontexten}, edition = {1}, publisher = {Springer}, doi = {10.1007/978-3-662-70949-8_3}, pages = {35 -- 48}, year = {2025}, abstract = {Schwingungen und Wellen zeigen sich in vielen Alltagsph{\"a}nomenen der Physik, d. h. in der Lebenswelt von Sch{\"u}lerinnen und Sch{\"u}lern. Dazu z{\"a}hlen in der Mechanik Beispiele wie Schaukeln, Seilwellen oder Wasserwellen am Strand, in der Akustik Schallwellen durch beliebige Ger{\"a}usche oder stehende Wellen in Musikinstrumenten und im Elektromagnetismus die allgegenw{\"a}rtigen elektromagnetischen Wellen. Letztere haben vielf{\"a}ltigste Anwendungen, z. B. Erhitzen mit Mikrowellenger{\"a}ten, Kommunizieren mit Smartphones, Daten{\"u}bertragung mit Lichtleitern oder Fotografieren mit Kameras, ganz zu schweigen von medizinischen Anwendungen der Endoskopie, des R{\"o}ntgens oder laserbasierten chirurgischen Eingriffen. Viele dieser Anwendungen haben ein enormes Motivationspotenzial in der Lehre, weshalb das Thema fest in Lehrpl{\"a}nen der Sekundarstufen verankert ist. Im Folgenden werden zun{\"a}chst allgemeine Grundlagen und Gemeinsamkeiten der Beschreibung beliebiger Wellen diskutiert, bevor das Hauptaugenmerk auf elektromagnetische Wellen und ausgew{\"a}hlte Anwendungen gelegt wird.}, language = {de} } @article{Vollmer2024, author = {Vollmer, Michael}, title = {Optical Phenomena in the Atmosphere}, series = {Encyclopedia of Atmospheric Sciences}, journal = {Encyclopedia of Atmospheric Sciences}, number = {2}, edition = {3}, publisher = {academic press}, doi = {10.1016/B978-0-323-96026-7.00177-6}, pages = {285 -- 306}, year = {2024}, abstract = {Following a brief description of the atmosphere and spectra of the Sun as dominant daytime light source, the most common optical phenomena within the troposphere are discussed, which are due to scattering of radiation with the constituents of the atmosphere. At first mirages, rainbows, coronas, iridescence, glories and halos are explained. Then light scattering phenomena which give rise to sunset colors, blue and colorful skies are presented as well as related phenomena like blue mountains, white clouds, green flashes and visual ranges. The review ends with a short survey of other less easily observable optical phenomena of the atmosphere and a very detailed bibliography.}, language = {en} } @book{Vollmer2024, author = {Vollmer, Michael}, title = {Optik und ihre Ph{\"a}nomene}, edition = {3}, publisher = {Springer}, isbn = {978-3-662-69308-7}, doi = {10.1007/978-3-662-69309-4}, publisher = {Technische Hochschule Brandenburg}, pages = {XXIII, 607}, year = {2024}, abstract = {Dieses Lehr-, Lern-, Fach- und Sachbuch pr{\"a}sentiert die Grundlagen der Optik in Theorie und ausf{\"u}hrlich beschriebenem Experiment sowie vielf{\"a}ltige faszinierende optische Ph{\"a}nomene. Ob in Vorlesungen, Seminaren, f{\"u}r Projektarbeiten, Schulunterricht oder Selbststudium - dieses Buch ist eine wertvolle Ressource f{\"u}r alle, die sich f{\"u}r Optik interessieren. Durch die große Zahl zitierter Originalarbeiten schl{\"a}gt es nicht nur die Br{\"u}cke zur Lehre sondern auch zur Forschung.}, language = {de} }