Some widely used optical measurement systems require a scan in wavelength or in one spatial dimension to measure the topography in all three dimensions. Novel hyperspectral sensors based on an extended Bayer pattern have a high potential to solve this issue as they can measure three dimensions in a single shot. This paper presents a detailed examination of a hyperspectral sensor including a description of the measurement setup. The evaluated sensor (Ximea MQ022HG-IM-SM5X5-NIR) offers 25 channels based on Fabry–Pérot filters. The setup illuminates the sensor with discrete wavelengths under a specified angle of incidence. This allows characterization of the spatial and angular response of every channel of each macropixel of the tested sensor on the illumination. The results of the characterization form the basis for a spectral reconstruction of the signal, which is essential to obtain an accurate spectral image. It turned out that irregularities of the signal response for the individual filters are present across the whole sensor.
Hyperspectral imaging opens a wide field of applications. It is a well established technique in agriculture, medicine, mineralogy and many other fields. Most commercial hyperspectral sensors are able to record spectral information along one spatial dimension in a single acquisition. For the second spatial dimension a scan is required. Beside those systems there is a novel technique allowing to sense a two dimensional scene and its spectral information within one shot. This increases the speed of hyperspectral imaging, which is interesting for metrology tasks under rough environmental conditions. In this article we present a detailed characterization of such a snapshot sensor for later use in a snapshot full field chromatic confocal system. The sensor (Ximea MQ022HG-IM-SM5X5-NIR) is based on the so called snapshot mosaic technique, which offers 25 bands mapped to one so called macro pixel. The different bands are realized by a spatially repeating pattern of Fabry-P´erot filters. Those filters are monolithically fabricated on the camera chip.
Single-molecule spectroscopy (SMS) at low temperature was used to study the spectral properties, heterogeneities and spectral dynamics of the chlorophyll a (Chl a) molecules responsible for the fluorescence emission of photosystem I (PS I). The fluorescence spectra of single PS I complexes are dominated by several red-shifted Chl a molecules categorized into red pools called C708 and C719. By polarization dependent measurements we demonstrate spectrally separate emissions corresponding to C708 and C719 in single PS I monomers and trimers. Moreover, we compared the results of SMS polarization dependent between monomeric and trimeric PS I complexes and give an estimation for the orientation between these red pools. As a consequence, we get new insight into the energy transfer towards and between the red Chl a molecules in PS I complexes.
Electron and energy transfer in proteins are key processes in bioenergetics. Their understanding on a molecular
level can serve as an important guideline for the design of nanoscale assemblies. Energy transfer between pigment
molecules requires a match between their transition energies for energy emission and absorption. The tuning
of these pigment energies in proteins is achieved by pigment-protein interactions. In general, these interactions
are regarded as static properties determined by the three-dimensional structure of pigment-protein complexes.
Employing single-molecule fluorescence spectroscopy we demonstrate that protein dynamics, even at cryogenic
temperatures, significantly influences the transition energy of pigments and, as a consequence, modulates energy
transfer pathways. This variability of excitation energy transfer pathways introduced by protein dynamics might
be important for the extreme robustness of photosystems.
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