Direction of arrival estimation and self-calibration techniques using an array of acoustic vector sensors: Theory, algorithms and applications

Microphones are the most popular devices used to convert sound into electrical signals. However, with the advent of sensor technology, transducers capable of measuring vector quantities are opening up many new possibilities. One such device is an acoustic vector sensor (AVS), which measures both acoustic pressure and particle velocity, and has...

New methods and applications of ptychography

This thesis addresses new methods and applications of ptychography which is a scanning Coherent Diffraction Imaging(CDI) method for reconstructing a complex valued object function from intensity measurements recorded in the Fraunhofer or Fresnel diffr- action region. The technique provides a solution to the so-called 'phase problem' and is found...

Theoretical Minimum Uncertainty of Single-Molecule Localizations Using a Single-Photon Avalanche Diode Array

Optical microscopes are fundamentally limited to a resolution of several hundreds of nanometers by the diffraction of light. Single-molecule localization microscopy (SMLM) circumvents this limit by sparsely exciting fluorescent molecules at different time instances. Single molecules can subsequently be localized with improved precision over the...

Physics and technology of time-of-flight PET detectors

The imaging performance of clinical positron emission tomography (PET) systems has evolved impressively during the last ∼15 years. A main driver of these improvements has been the introduction of time-of-flight (TOF) detectors with high spatial resolution and detection efficiency, initially based on photomultiplier tubes, later silicon...

Parameter retrieval of small particles in dark-field Fourier ptychography and a rectangle in real-space ptychography

We present a parameter retrieval method which incorporates prior knowledge about the object into ptychography. The proposed method is applied to two applications: (1) parameter retrieval of small particles from Fourier ptychographic dark field measurements; (2) parameter retrieval of a rectangular structure with real-space ptychography. The...

Imaging sensor data modelling and evaluation based on optical composite characteristics: Investigation of data quality for inline inspection

Automated Fibre Placement is a common manufacturing technique for composite parts in the aero-space industry. Therefore, a visual part inspection is required which often covers up to 50% of the actual production time. Moreover, the inspection quality of this manual step fluctuates significantly. A camera-based automated inline inspection is...

Optimal Sensor Placement for Calibration-Involved Radio Astronomy Imaging Applications

In radio astronomy (RA), one of the key tasks is the estimation of the celestial source powers, i.e. imaging. To maximize the performance, it is crucial to optimize the receiver locations before the construction of a telescope array. However, although system calibration is an integral and crucial process of imaging, it has rarely been addressed...

Sparse Signal Bands Selection for Precise Time-based Ranging in Terrestrial Positioning

Time-based ranging accuracy is inversely proportional to the signal bandwidth. A larger the signal bandwidth leads to a higher accuracy of time delay estimation, but more complex hardware is needed. Alternatively, we explore the idea of using multiple narrow signal bands (e.g., 10 MHz of each) to create a large virtual signal bandwidth, which...

Accurate estimation of the attenuation coefficient from axial point spread function corrected OCT scans of a single layer phantom

The attenuation coefficient (AC) is a property related to the microstructure of tissue on a wavelength scale that can be estimated from optical coherence tomography (OCT) data. Since the OCT signal sensitivity is affected by the finite spectrometer/detector resolution called roll-off and the shape of the focused beam in the sample arm,...

Radar networks performance analysis and topology optimization

The ultimate goal of any sensing system is to build situation awareness. Existing<br/>solutions for a single radar node that have to assure extended areas of coverage with<br/>high resolution measurements (in range, cross-range, and Doppler) are physically<br/>cumbersome (large antenna size) and typically require large operational resources ...

Directional maximum likelihood self-estimation of the path-loss exponent

The path-loss exponent (PLE) is a key parameter in wireless propagation channels. Therefore, obtaining the knowledge of the PLE is rather significant for assisting wireless communications and networking to achieve a better performance. Most existing methods for estimating the PLE not only require nodes with known locations but also assume an...

Single emitter localization analysis in the presence of background

Localization microscopy for imaging at the nano-scale relies on the quality of fitting the emitter positions from the measured light spots. The type and magnitude of the noise in the detection process, the background light level and the Point Spread Function model that is used in the fit are of paramount importance for the precision and accuracy...