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DTSTAMP:20261021T123201Z
LAST-MODIFIED:20160727T191043Z
DTSTART:20160804T143000Z
DTEND:20160804T153000Z
UID:event1626@bu.edu
URL:http://physics.bu.edu/internal/events/show/1626
SUMMARY:Statics and Dynamics of Electrothermal Micromirrors
DESCRIPTION:Featuring Jessica Morrison\n\nPart of the PhD Final Oral Exams.
	\n\nExamining Committee: David Bishop\, Thomas D.C. Little\, Shyamsunder Er
	ramilli\, Robert Carey\, David Campbell\n\nAbstract:\n\nAdaptive and smart 
	systems are growing in popularity as we shift toward personalization as a c
	ulture. With progressive demands on energy efficiency\, it is increasingly 
	important to focus on the utilization of energy in a novel way. This thesis
	 investigates a microelectromechanical system (MEMS) mirror with th
	e express intent to provide flexibility in solid state lighting (SSL). By 
	coupling the micromirror to an optical source\, the reflected light may be
	 reshaped and directed so as to optimize the overall illumination profile.
	 In addition\, the light may be redirected in order to provide improved sig
	nal strength in visible light communications (VLC) with negligible impact o
	n energy demands.\n\nWith flexibility and full analog control in mind\, th
	e design of a fully integrated tip-tilt-piston micromirror with an addition
	al variable focus degree of freedom is outlined. Electrothermal actuators a
	re used to both steer the light and tune the focal length. A detailed discu
	ssion of the underlying physics behind composite beams and thermal actuator
	s is addressed. This leads directly into an overview of the two main mirror
	 components\, namely the segmented mirror and the deflection actuators.\n\
	nAn in-depth characterization of the dynamics of the mirror is discussed in
	cluding the linearity of the thermal response. Frequency domain analysis of
	 such a system provides insight into tunable mechanical properties such as 
	the resonant frequency and quality factor. The degenerate resonant modes ca
	n be separated significantly. It is shown that the frequency response may 
	be tuned by straining specific actuators and that it follows a predictable
	 pattern. As a result\, the system can be scanned at increasingly large ang
	les. In other words\, coupled mechanical modes allow variable damping and a
	mplification. A means to determine the level of coupling is examined and t
	he mode shape variations are tracked as a function of the tuning parameters
	.\n\nFinally\, the applications of such a device are explored and tested. S
	uch applications include signal-to-noise ratio (SNR) enhancements in VLC of
	 up to 40 dB and color tunable steerable lights using laser diodes. A brief
	 discussion of the implications of dynamic illumination and tunable systems
	 is juxtaposed with demonstrated integration of an electrothermal micromirr
	or and an all digital driver.\n\n![Jessica](/resources/event-image/1626/852
	256c_original)
LOCATION:PHO 901\, 8 Saint Mary's Street\, 02215
STATUS:CONFIRMED
CLASS:PUBLIC
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