In der vorliegenden Arbeit werden optische Schichteigenschaften von Zirren durch räumlich und zeitlich kombinierte flugzeuggetragene Messungen zusammen mit Strahlungstransfersimulationen untersucht. Diese räumlich koordinierten Strahlungs– und Mikrophysikmessungen oberhalb, unterhalb und innerhalb des Zirrus werden mittels eines Forschungsflugzeuges (Learjet 35A) in Kombination mit einem Schleppkörper namens AIRTOSS (AIRcraft TOwed Sensor Shuttle) realisiert. AIRTOSS wird dabei vom Flugzeug aus mittels einer Winde abgelassen und wieder eingeholt. Die maximale Seillänge beträgt 4 km. Im Rahmen des AIRTOSS–ICE–Projekts (Inhomogeneous Cirrus Experiment) wurden während zweier Messkampagnen über der Nord– und Ostsee im Frühjahr und Spätsommer 2013 flugzeuggetragene Beobachtungen der Zirruseigenschaften durchgeführt. Beispielmessungen eines Messfluges werden in dieser Arbeit gezeigt, welche den Nutzen der simultanen Strahlungsmessungen mittels zweier Messplattformen aufzeigen. Aus den Messungen der spektralen Flussdichten oberhalb und unterhalb des Zirrus werden die optischen Schichteigenschaften wie Transmissivität, Reflektivität und Absorptivität und die Albedo der Wolkenschicht ermittelt. Die flugzeuggetragenen Untersuchungen werden durch Sensitivitätsstudien gestützt, basierend auf einem eindimensionalen Strahlungstransfermodell. Dies dient der Charaktierisierung des Einflusses variierender, optischer und mikrophysikalischer Zirruseigenschaften (Eiskristallform, Partikelgröße und optische Dicke) auf die optischen Schichteigenschaften und den solaren Strahlungsantrieb des Zirrus. Weitere Studien zeigen den Einfluss einer darunterliegenden Flüssigwasserwolke auf die Zirruseigenschaften. Eine niedrige Wolkenschicht führt zu Abweichungen der Schichteigenschaften des Zirrus von 85%. Die Nichtberücksichtigung niedriger Wolken unterhalb einer Zirrusschicht führt zu einer deutlichen Überschätzung des Strahlungsantriebs des Zirrus um Faktor 5. / In this thesis cirrus optical layer properties are investigated by truly collocated measurements and supplementary radiative transfer simulations. The close collocation of the radiative and microphysical measurements, above, beneath and inside the cirrus, is obtained by using a research aircraft (Learjet 35A) in tandem with a towed platform called AIRTOSS (AIRcraft TOwed Sensor Shuttle). AIRTOSS can be released from and retracted back to the research aircraft by means of a cable up to a distance of 4 km. Data were collected in two field campaigns above the North and Baltic Sea in spring and late summer 2013 in the framework of the AIRTOSS–ICE (AIRTOSS – Inhomogeneous Cirrus Experiment) project. Exemplary, results from one measuring flight are discussed also to illustrate the benefits of collocated sampling. The spectral optical layer properties of cirrus are derived from simultaneous and vertically collocated measurements of spectral upward and downward solar irradiance above and below the cloud layer and concurrent in situ microphysical sampling of the ice particle size distributions. From the irradiance data the optical layer properties (transmissivity, reflectivity, and absorptivity) and the cloud top albedo of the observed cirrus layer are obtained. These airborne observations are supported by sensitivity studies using one–dimensional radiative transfer modelling to characterize the effect of varying cirrus optical and microphysical properties (ice crystal shape, particle size, and cloud optical thickness) on the cirrus optical layer properties, as well as on the solar cirrus radiative forcing. Further studies show the impact of an underlying low–level liquid water cloud on the mentioned cirrus properties. A low–level cloud causes differences in the layer properties of the cirrus by 85%. If low–level clouds below cirrus are not considered the solar cooling due to the cirrus is significantly overestimated by up to a factor of 5.

Before year 1895, the doctors could only make a probable diagnosis based on what the patient could tell and it was hurt and there was no discernable change to the outside of the body. With X-ray, it was possible to see inside the patient without first cutting it, you can say that the X-ray was the starting point for diagnostic imaging.The further development of X-ray gave CT (Computed Tomography), where X-ray tubes and detectors rotate around the patient while the patient table moves. Besides CT also developed MRI (Magnetic Resonance Imaging), PET (Positron Emission Tomography) and Ultrasound. Common to these methods is that the produced 3D images.In 1990 a completely new approach for diagnostic imaging, OCT (optical coherence tomography), by measuring the phase shift and the intensity of reflected light, it provides real-time and non-destructive measurements (in vivo) a resolution of 1 to 15 microns, much higher than all other standard imaging techniques. You could say that OCT machine can be compared to ultrasound, which uses the reflection of sound waves to interpretation.The first OCT machines were of type TD (Time Domain), these had low resolution and low scanning speed. In 2005 came the SD-OCT, they had higher resolution and scanning speed, SD stands for spectral domain, SD-OCT is sometimes called FD-OCT as Fourier transformed signals and operating in the frequency domain.The development of OCT machines are only in their infancy, resolution, scanning speed and accuracy will increase all the time, this allows new uses and ways to diagnose developed. OCT can be used in such Oncology, MSD (Musculoskeletal disorders), cardiovascular medicine, teeth, nerves, but the largest field is the eye and then the back of the eye called the retina (retina).This thesis is limited to the eye, the purpose is to provide input to those who are likely to purchase an OCT-machine, but also show the measurement data OCT-machines are performing and how to use the OCT-machine more than to see age-related macular degeneration. Another aim is to increase understanding of the physics behind an OCT-machine for ease of understanding the output given.The manufacture/model that have selected for evaluation are Zeiss Cirrus 4000, Topcon 3D OCT-2000 and Heidelberg Spectralis, the reason is that there are only these three on the Swedish market and all are SD-OCT. The way to evaluate OCT-machines is to scan performance and what the various analysis programs can handle. Furthermore, each OCT-machine scans the macula and optic disk on a experimental person/ reference eye, in order to get the output of the precision, or if you want to call it repeatability, which is very important if one wants to follow a solitary disease course.The conclusion of this thesis is to OCT machines are quite similar. When it comes to ease of use when doing scans is the Cirrus is lightened by the use of the extra screen where you always look eye (iris camera), which makes it easy to adjust the sharpness and position of the mouse buttons. Topcon and Heidelberg is not difficult to use but requires more experience of the person making the OCT scans. Most measurement functions in the analysis program is Topcon and Heidelberg and best accuracy/repeatability is Heidelberg, both the macula and RFNL.OCT machine is a good tool to use on the anterior segment, but in the case the precision allows the precision used to monitor RNFL thickness changes in those with glaucoma. / <p>Validerat; 20131029 (global_studentproject_submitter)</p>