Forum Bildverarbeitung 2012

Bildverarbeitung spielt in vielen Bereichen der Technik zur effizienten und objektiven Informationserfassung eine Schlüsselrolle und hat sich in vielen Anwendungen einen unverzichtbaren Platz erobert. Von besonderer Bedeutung ist dabei eine zielführende Verarbeitung der erfassten Bildsignale. Das "Forum Bildverarbeitung 2012" greift diese hochaktuellen Entwicklungen sowohl hinsichtlich der theoretischen Grundlagen, Beschreibungsansätze und Werkzeuge als auch relevanter Anwendungen auf

Three-Dimensional Imaging of Cold Atoms in a Magneto-Optical Trap with a Light Field Microscope

Imaging of trapped atoms in three dimensions utilizing a light field microscope is demonstrated in this work. Such a system is of interest in the development of atom interferometer accelerometers in dynamic systems where strictly defined focal planes may be impractical. A light field microscope was constructed utilizing a Lytro® Development Kit micro-lens array and sensor. It was used to image fluorescing rubidium atoms in a magneto-optical trap. The three-dimensional (3D) volume of the atoms is reconstructed using a modeled point spread function (PSF), taking into consideration the low magnification (1.25) of the system which changed typical assumptions in the optics model for the PSF. The 3D reconstruction is analyzed with respect to a standard off-axis fluorescence image. Optical axis separation between two atom clouds is measured to a 100µm accuracy in a 3mm deep volume, with a 16µm in-focus standard resolution and a 3.9mm by 3.9mm field of view. Optical axis spreading is observed in the reconstruction and discussed. Absorption imaging with the light field microscope is also analyzed. The 3D images can be used to determine properties of the atom cloud with a single camera and single atom image which will be needed to create atom interferometers capable of inertial navigation

Luminescence in Lithium Borates

Spectrometry methods are used to identify and characterize point defects in single crystals of lithium tetraborate (Li2B4O7) and lithium triborate (LiB3O5) doped with silver or copper, and explore the role of these point defects in luminescence. New defects are identified in Ag-doped including: lithium vacancy substitutional-silver-ion defect-pairs (hole trap); isolated lithium vacancies (hole trap); isolated oxygen vacancies (electron trap); interstitial-silver-ion substitutional-silver-ion defect pairs (electron trap); isolated interstitial silver ions (electron trap); and interstitial-silver-ion lithium-vacancy defect pairs (electron trap). Defect models are proposed, and adjustments made to defect models known defects. Defects in Ag-doped LiB3O5 and Cu-doped LiB3O5 are identified including: two species of interstitial-silver-ions (electron traps); isolated-substitutional-silver-ion (hole trap); lithium vacancy substitutional-silver-ion defect pairs (hole trap); interstitial-silver-ion substitutional-silver-ion defect pairs (electron trap); a species of interstitial-copper-ion (electron trap); isolated-substitutional-copper-ion (hole trap); and lithium vacancy substitutional-copper-ion defect pairs (hole trap). Based on this assessment, Ag-doped LiB3O5 is a promising TL and OSL dosimetry material while Cu-doped LiB3O5 is not

The Optimal Axial Interval in Estimating Depth from Defocus

We analyze the effect of perturbations on the estimation of Depth from Defocus (DFD) implemented by changing the focus setting (e.g., axially moving the sensor). The analysis yields the optimal change of focus setting, and the spatial frequencies for which estimation is most robust. For stable estimation at all spatial frequencies, the change in focus setting should be less than twice the depth of field. For the most robust estimation in the highest spatial frequencies the axial interval should be equal to the depth of field. 1. Introduction In recent years, range imaging based on the limited depth of field (DOF) of lenses has been gaining popularity. Depth from Defocus (DFD) is an elegant method since it enables depth estimation based on only two images of the scene, taken from the same viewpoint. The defocus blur is made different in the two images by changing the internal settings of the imaging system. The effect of those changes on the defocus blur can be modeled either empirica..