Optik und Mechatronik
Refine
Year of publication
Document Type
- Conference Proceeding (51)
- Article (35)
- Master's Thesis (8)
- Bachelor Thesis (6)
- Book (2)
- Patent (2)
- Doctoral Thesis (1)
- Report (1)
Language
- English (106) (remove)
Keywords
- Myopia (2)
- Blinking (1)
- Blinzeln (1)
- Choroidal thickness (1)
- Comparison metrics (1)
- Defocus (1)
- Diffusion (1)
- Edge Detection (1)
- Eye Tracking, Vigilanz, Aufmerksamkeit, visuelle Exploration, Perimetrie (1)
- Eye tracking (1)
Institute
- Optik und Mechatronik (106)
Identification and quantitative segmentation of individual blood vessels in mice visualized with preclinical imaging techniques is a tedious, manual or semiautomated task that can require weeks of reviewing hundreds of levels of individual data sets. Preclinical imaging, such as micro-magnetic resonance imaging (μMRI) can produce tomographic datasets of murine vasculature across length scales and organs, which is of outmost importance to study tumor progression, angiogenesis, or vascular risk factors for diseases such as Alzheimer’s. Training a neural network capable of accurate segmentation results requires a sufficiently large amount of labelled data, which takes a long time to compile. Recently, several reasonably automated approaches have emerged in the preclinical context but still require significant manual input and are less accurate than the deep learning approach presented in this paper—quantified by the Dice score. In this work, the implementation of a shallow, three-dimensional U-Net architecture for the segmentation of vessels in murine brains is presented, which is (1) open-source, (2) can be achieved with a small dataset (in this work only 8 μMRI imaging stacks of mouse brains were available), and (3) requires only a small subset of labelled training data. The presented model is evaluated together with two post-processing methodologies using a cross-validation, which results in an average Dice score of 61.34% in its best setup. The results show, that the methodology is able to detect blood vessels faster and more reliably compared to state-of-the-art vesselness filters with an average Dice score of 43.88% for the used dataset.
The use of computers spread among the population, both for work and leisure purposes. This poses an increased risk factor for dry eye disease, a multifactorial disease influencing the surface of the eye. With the recent increasing usage of head-mounted displays, it is critical to determine whether or not they have the same impact on the tear film as conventional screens.
Feedback management in hearing aids and its challenges have been there for over 60 years. The basic principles of feedback management are still in use to prevent the hearing aids from oscillation. This work focusses on the feedback management in custom style hearing aids by comparing four different Invisible-In-the-Canal (IIC) hearing aids. Four test set-ups were created to find valid and reli-able methods and set-ups to test custom hearing aids for their feedback management. The goal was to find out if they could provide 1) stable gain, 2) good sound quality, 3) indicate specific frequencies audible feedback occurs and 4) to test the clinical robustness through subjective experience rating. The principle was: matched gain – matched acoustics.
Purpose: The aim is to be able to advise patients on the choice of sports and exercises regarding the effects on the intraocular pressure.
Methods: The search engines Google Scholar and PubMed were used to search for suitable studies. The studies were summarized, and the most important data were collected in one table for each study. The effect on the IOP was extracted or, if not given in the article, calculated by the difference of means of the IOP after or during exercise, and the baseline IOP before, whenever these values were available.
Findings: A total of 47 studies out of the years 1990 to 2020 that investigated the influence on the IOP of the most popular sports actively practiced in Germany were reviewed and summarized: twelve for running, sixteen for fitness/ weight training, one for swimming/diving, twelve for cycling, four for hiking, and two for yoga.
Conclusions: Throughout all studies and sports it was seen that physical fitness stabilized the IOP. Higher
intensity of exercise led to higher fluctuations of the IOP. Moderate endurance training keeps the IOP fluctuations low and may lead to a lower baseline IOP if practiced on a regular base. Fitness and weight training lead to fluctuations of the IOP in a pronounced manner when performed at moderate and high intensity. Therefore, only a moderate training can be recommended if there is need to keep the IOP stable. Isometric exercise is not recommended as it provokes a rise of the IOP even when performed with light loads. The Valsalva Maneuver should always be avoided as it leads to additional fluctuations of the IOP. Also, the IOP behaved more stable during resistance training when higher fitness was present.
Subsea shut-off device
(2021)
Improved light scattering characterization by BSDF of automotive interior and 3D printed materials
(2021)
Preliminary study: Polishing force measurement by viscosity - the return of ketchup polishing
(2021)
Novel myopia control spectacle lenses induce peripheral contrast reduction via optical diffusion. It is suggested, that the contrast reduction alters retinal processes in the low-level neural circuity, leading to an inhibition of eye growth. The purpose of this thesis is to evaluate the influence of full-field contrast reduction on low-level neural processing of the retina, described by the edge contrast sensitivity.
This research project is of particular importance since there is a lack of adequate data on pediatric eye and vision disorders in Russia, particularly in the Volga region. In the present study, we estimate the prevalence of vision disorders among school-aged children who participated in a vision screening program in Samara, Russia. The relationship between learning-related visual dysfunctions is explored in depth, such to illustrate the connection between vision and learning. Hence, a key feature in this study is the inclusion of binocular vision disorders among the conditions tested.
The direct ophthalmoscope is a retinal screening tool that has been in existence and development for more than 150 years, yet, the rapid influence of technological evolution in screening tools, has left the direct ophthalmoscope untouched. The main purpose of this master thesis is to determine if the direct ophthalmoscope has reached its maximum potential of development and, additionally, to determine if a further development, including a more electronic input, would be feasible.