This Thesis proposes phase modulating interferometry as an alternative to phase stepping and phase-shifting interferometry for use in the shape and displacement characterization of microelectromechanical systems (MEMS) [Creath, 1988; de Groot, 1995a; Furlong and Pryputniewicz, 2003]. A phase modulating interferometer is developed theoretically with the use of a stroboscopic illumination source and implemented on a Linnik configured interferometer using a software control package developed in the LabVIEWâ„¢ programming environment. Optimization of the amplitude and phase of the sinusoidal modulation source is accomplished through the investigation and minimization of errors created by additive noise effects on the recovered optical phase. A spatial resolution of 2.762 µm over a 2.97x2.37 mm field of view has been demonstrated with 4x magnification objectives within the developed interferometer. The measurement resolution lays within the design tolerance of a 500Ã… ±2.5% thick NIST traceable gold film and within 0.2 nm of data acquired under low modulation frequency phase stepping interferometry on the same physical system. The environmental stability of the phase modulating interferometer is contrasted to the phase stepping interferometer, exhibiting a mean wrapped phase drift of 40.1 mrad versus 91 mrad under similar modulation frequencies. Shape and displacement characterization of failed µHexFlex devices from MIT's Precision Compliant Systems Laboratory is presented under phase modulating and phase stepping interferometry. Shape characterization indicates a central stage displacement of up to 7.6 µm. With a linear displacement rate of 0.75 Ã…/mV under time variant load conditions as compared to a nominal rate of 1.0 Ã…/mV in an undamaged structure [Chen and Culpepper, 2006].

The power and energy optimization of a device can lead to a reduced cost, smaller area, better temperature performance, and higher lifetime. Furthermore, in systems that have limited power budget, it allows running simultaneously more functionalities or using features that require higher power demand.Therefore, both from the user and the company perspective, the value of a product increases as the energy optimization improves. For nighttime surveillance video recording, it is common to use infrared illumination to light the targetscene, which draws a significant portion of the total camera energy consumption. This master thesis examines and discusses how stroboscopic infrared illumination can enhance the energy efficiency in videorecording cameras with rolling shutter image sensors. This report analyzes LED driver circuits, recommends methodologies, and sorts the most relevant parameters to help to dimension and design the illumination system for a light-strobing system. A promising field of use for this technique has been found to be the license-plate recognition (LPR) scenario, for which this thesis dedicates a chapter in this document. This project has been developed at AXIS Communications, where a prototype has been built for one of their network security cameras. The prototype has been tested for LPR for both strobing light systems and conventional IR lighting systems. The results obtained prove that the energy efficiency of the illumination system can be improved more than 95% when stroboscopic illumination is used. / Effektförbrukning och energioptimering av en produkt kan leda till lägre kostnad, mindre storlek, bättre temperaturprestanda och högre livslängd. I system med begränsad effektbudget möjliggör detta dessutom aktivering av fler funktioner samtidigt, eller användning av funktioner med högre strömförbrukning. Därmed gör energioptimering att produktens värde ökar både för användaren och för företaget som tillverkar den. För videoinspelning med övervakningskamera nattetid är det vanligt att använda infraröd belysning för att belysa scenen, vilket ofta förbrukar en betydande del av kamerans totala effektbudget. Detta examensarbete undersöker och diskuterar hur blixtrande (Eng. strobed) infraröd belysning kan förbättra energieffektiviteten vid videoinspelning med bildsensorer med rullande slutare. I denna rapport analyseras LED-drivkretsarna, metodik rekommenderas samt att de mest relevanta parametrarna för att dimensionera och designa ett belysningssystem baserad på strobed IR-belysning sorteras ut. Ett lovande användningsområde för denna teknik har visat sig vara LPR-scenariot (License Plate Recognition), vilket diskuteras i ett eget kapitel i denna rapport. Projektet har genomförts på AXIS Communications, där en prototyp har byggts baserat på en av dess nätverkskameror. Prototypen har utvärderats LPR-sammanhang med både strobed och konventionellt IR belysningssystem. De erhållna resultaten visar att energieffektiviteten hos belysningssystemet kan förbättras med mer än 95% när blixtrande belysning används.