Extremely large telescopes (ELTs) are expected to be one of the most promising astronomical observation instruments when it comes to observing exoplanets. During observations, however, Earth’s atmosphere introduces optical distortion, which needs to be corrected. For this reason, a wavefront sensor (WFS) will be developed that comprises a 100 ⇥ 100 array of kinetic inductance detectors (KID), superconductor-based photodetectors. The main advantage of KIDs in an array is their ability to be multiplexed on a single read out line by designing each KID to operate at a different frequency. The signal of an individual KID can essentially be described as a dip in the transmission signal of the readout signal. Upon the fabrication of these KID arrays, however, these dips may have shifted as so-called frequency scatter (or f-scatter), which severely disorders the readout signal. The f-scatter cannot be determined based solely on the readout signal as it contains no information about which KID each individual signal originates from. This paper manages to provide a solution in the form of an experimental method in which the KID array is scanned along the x- and y-axis to produce a spatial map. To realize this, an optical setup was designed and constructed, based on a single-lens system with a magnification of M = 1.22. By implementing a CCD camera, the KID array could be live imaged to align the setup accordingly. Thanks to numerous other alignment measures, the setup was able to scan the entire KID array along the x- and y-axis in 45 scans per axis. Based on the difference in transmission, a 45x45 spatial map was constructed, which was manually scaled down to 20x20. This 20x20 spatial map presented the location of KIDs on the fabricated detector array based on their measured operating frequency. By comparing this with the spatial map of the KID array design, the standard deviation in the fractional frequency deviation was determined, σ_δf/f = 5.92 · 10^-3. This result shows the experimental method is able to effectively unveil the severity of the f-scatter in the studied 20x20 KID array. Despite the potency of the presented method, the biggest giveaway of its flaws is a reduced pixel yield on the 20x20 spatial map from 400 to 374 pixels. The developed data analysis is able recognize multiple complications, which can be mitigated by optimizing readout parameters to improve the quality of the signal. Additionally, one-to-one imaging is far too restricting for advanced scanning techniques due to its fixed M. Appropriate suggestions for improving the lens systems would be implementing the Cooke triplet or a two-lens system that utilizes the principle of virtual imaging.

Sustainable energy technologies are ever-increasing in popularity, not only among companies but also among consumers. Photovoltaic, or PV, cells are amongst the most well known in this field. This project was set up for designing a PV-powered UAV that is able to generate an albedo map of an area equal or bigger than the campus of the TU Delft in a single run. PV cells, however, are highly susceptible to changes in weather conditions and have a range of voltages at which these cells can supply power. Besides that, unnecessary losses occur if the so-called ’Maximum Power Point’ (MPP) is not tracked. In this thesis, a boost converter is proposed for the aforementioned system to implement the maximum power point tracking and supply the, by the PV system produced, power as efficiently as possible to the UAV power system.

A gas-cell-based calibration setup was designed to evaluate the wideband response of sub-millimeter spectrometers like DESHIMA (DEep Spectroscopic High-redshift MApper). The use of low pressure gas emission spectra allowed for accurate calibration of the absolute frequency response, and to test the detectability of faint emission spectra with long integration times. This is important to understand and evaluate systematic errors and noise profiles of sub-millimeter astronomical spectrometers before their telescope campaigns. The setup consisted of a low pressure (~mbar) gas at room temperature in a high vacuum (<10-3 mbar) chamber in front of a 77K N2 background. A double-winged rotating chopper was used for signal modulation of the on- and off-source paths to reduce the low-frequency noise profile. The setup has been able to successfully detect the emission spectra of nitrous oxide at 30 mbar and methanol at 1 mbar in the frequency range of 332 to 377 GHz with the prototype DESHIMA spectrometer. Our models showed that lower pressures should be detectable over similar averaging times. The standing spectrum showed to be too irregular for detecting spectral lines in a single measurement. A second measurement was required to subtract the standing features, which extended the total time required beyond the current system stability. Detailed analysis into optical resonances has shown the importance of anti-reflective (AR) coatings on the main optical interfaces to improve the detectability of the emission spectra. We adapted sub-wavelength pyramid gratings milled into TOPAS windows to reduce a standing wave in the output spectrum of the gas cell setup. Stability of the setup was shown for observation times of up to ~103 seconds before environmental noises became dominant. Extensive stability testing has shown the impact of key components in the setup. A two-stage post-processing algorithm was developed to successfully reduce instabilities in the data by removing linear drifts and by removing the common profile over simultaneous read-out data.

At the center of every galaxy there is a super-massive black hole of a million or more solar masses. In most galaxies the presence of this black hole can only be detected through its gravitational attraction, which affects the motion of nearby stars. However, in about 10% of the galaxies the super-massive black hole is the engine of one of the most luminous phenomena in the universe: an active galactic nucleus (AGN). In the local universe there are two types of AGN: ‘Radiative-mode’ and ‘Jet-mode’ AGN. In this thesis I show that these two AGN types are hosted by different galaxies and have different infrared properties. ‘Radiative-mode’ AGN are the ‘classical’ AGN which are bright emitters across the entire electromagnetic spectrum. They are thought to be powered by a super-massive black hole accreting matter at a high rate. I show that ‘radiative-mode’ AGN are predominantly found in intermediate mass galaxies with blue and green optical colors. These colors are indicative of active or recently terminated star formation and a young stellar population. Due to the presence of torus of hot dust near the black hole, galaxies with a ‘radiative-mode’ AGN typically show an excess of mid-infrared emission. ‘Jet-mode’ AGN lack the bright optical emission and excess infrared emission of ‘jet-mode’ AGN and can only be identified by means of their radio jet – a stream of relativistic particles that can reach far outside the AGN’s host galaxy. This absence of electromagnetic radiation and prominence of the radio jet is thought to be the result of the low accretion rate of the super-massive black hole driving this AGN type. I show that ‘jet-mode’ AGN have a strong preference for the most massive galaxies, which typically have little star formation. The presence or absence of a dusty torus and the resulting difference in broadband mid-infrared emission could be a powerful tool to separate ‘radiative-mode’ and ‘jet-mode’ AGN without using spectroscopy. Unfortunately, the inherent scatter in the mid-infrared emission of galaxies due to dust heated by stars is too large to separate the two populations reliably. Far-infrared observations could help resolve this, by constraining the mid-infrared contribution of dust heated by stars. However, current far-infrared surveys do not have the depth or the area to give the number statistics required to calibrate this procedure. In this thesis I have investigated the properties of microwave kinetic inductance detectors. These detectors will enable the far-infrared instruments with 10.000 pixels as a result of their inherent potential for frequency domain multiplexing. This is a huge leap from the 100 pixel far-infrared instruments currently on telescopes. I have shown that microwave kinetic inductance detectors made from NbTiN and Al can satisfy all the requirements to enable a new generation of large format far-infrared cameras, which are required to constrain the far-infrared emission of many galaxies.@en

Magnetic Kinetic Inductance Detectors (MKIDs) are very good radiation detectors which are even capable of single photon detection in the near-infra red and higher frequency range. MKIDs are currently used to detect exoplanets and the goal is to also retrieve information of the atmosphere of exoplanets. However, MKIDs don’t have the photon absorption efficiency and resolving power to do this yet. In this thesis we look at the single photon pulses of a new superconducting material, beta phased tantalum (β-Ta), since this material shows promising properties for MKIDs. The single photon pulse shapes of this material are not yet fully understood. Therefore we will create models for the quasiparticle dynamics in β-ta to try and further our understanding of the single photon pulses in this material. From the Rothwarf-Taylor equations we derive multiple models. These are then tested on the data. We first try the double exponential model which does not work. Then we look at the 1/t model and this model does seem to work better. We propose a different response time of the system. Fitting a new response time we get a very good fit to the single photon pulses. The main hypothesis is that there is an extra relaxation time for the quasiparticles as they need to distribute themselves throughout the superconductor. We see that the fitted response time is wavelength dependent which would support the hypothesis. We conclude that the 1/t model with an adjusted response time explains the single photon pule shapes the best.

Magnetic Kinetic Inductance Detectors (MKIDs) are very good radiation detectors which are even capable of single photon detection in the near-infra red and higher frequency range. MKIDs are currently used to detect exoplanets and the goal is to also retrieve information of the atmosphere of exoplanets. However, MKIDs don’t have the photon absorption efficiency and resolving power to do this yet. In this thesis we look at the single photon pulses of a new superconducting material, beta phased tantalum (β-Ta), since this material shows promising properties for MKIDs. The single photon pulse shapes of this material are not yet fully understood. Therefore we will create models for the quasiparticle dynamics in β-ta to try and further our understanding of the single photon pulses in this material. From the Rothwarf-Taylor equations we derive multiple models. These are then tested on the data. We first try the double exponential model which does not work. Then we look at the 1/t model and this model does seem to work better. We propose a different response time of the system. Fitting a new response time we get a very good fit to the single photon pulses. The main hypothesis is that there is an extra relaxation time for the quasiparticles as they need to distribute themselves throughout the superconductor. We see that the fitted response time is wavelength dependent which would support the hypothesis. We conclude that the 1/t model with an adjusted response time explains the single photon pule shapes the best.