الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 194 |  |  |
| | | from | 194 | | |
Abstract
The MEMS Scanner, or Microscanner, is a component of Micro-Opto-Electro-Mechanical
systems (MOEMS).They are basically small mirrors (in the range of few μm to few mm)
actuated by a MEMS actuator, to reflect a laser beam into a certain point in space. The
movement of such mirrors is modulated as the application requires.
Indeed, microscanners have a large market in today’s industry, as they serve many applications.
from complex display systems, to simple barcode scanners; MEMS scanners offer numerous
solutions to several technological challenges. Additionally, they are a key component in many
biomedical imaging devices, like the Optical coherence tomography (OCT). However to reach
industrial specifications, the fabrication methods must be simplified enough for the final product
to become economically feasible. It also must become integrated with other optical components.
The work of this thesis is to design, implement, and test a MEMS based microscanner that meets
certain specifications. Moreover, it features a cheap fabrication methodology that is compliant
with the Deep Reactive Ion Etching (DRIE) technology. The final device needs also to be
integrated with any other optical module, including the OCT system. This would further reduce
the cost due to its simple fabrication and the corresponding simple alignment-free assembly.
Moreover, the design was done using flat mirrors, which eliminated any optical constrictions on
the nature of the beam used to perform the scan.
The main contribution of this thesis is comprised of:
1- The design and fabrication of a MEMS scanner that is in-plane and self-aligned where the Single Mode Fiber is inserted in a micro-machined fiber groove etched by DRIE.
2- Improvising a novel method to enable the optical characterization of reflected spots from scanners at high speeds while it’s at resonance to draw the shape of this spot periodically.
3- The design and testing of a new probe configuration for a Common Path OCT head that enabled the use of complex optical devices like the scanner creating two and three dimensional images.
Furthermore, and since the out of plane actuator, staggered vertical comb drive, demonstrates a nonlinear behavior, its actuation is limited to resonant actuation only. To solve this issue, an algorithm for optimization of the design was proposed and tested by simulations, to achieve linear actuation. The results were promising and they were published. This allows a linear DC actuation scheme of out of plane actuation, and thus opens the door for many applications for the linear-2D scanner
This thesis consists of seven chapters. The first chapter of this thesis introduces the reader to the work presented, the objectives, and motivations. The second chapter will discuss the applications of MEMS scanners, as well as a survey on the current state of the art found in literature. Additionally, the main theory of the Optical Coherence Tomography (OCT) are explained as a direct application to our work and measurements.
The third chapter will present the concept of the actuator design as well as the spring system. Additionally, the design of the compliant springs used will be explained. It will also present the theory behind the new and novel work in these domains as well as their basic operation. Then the two dimensional scanners will be discussed in the fourth chapter, and the out of plane actuation required to build such scanners are explained.
Chapter five will be focused on the design, simulation, and fabrication of self-aligned in-plane scanners with monolithic compliant structures and flat mirrors. The use of compliant structures allowed for using simple lateral comb-drives to produce rotary actuation, and thus achieve scanning mechanisms that are in-plane and fully integrable with good optical properties and at custom operating frequencies that matches the specifications of the biomedical application chosen. Moreover, a brief theoretical background of the curved mirror scanners used for testing the possibility of using integrated scanners with OCT is provided.
As for the sixth chapter, it presents the experimental measurements of the novel method in building a biomedical probe as a direct application, as well as the novel compliant microscanner structure to confirm the theoretical allegation of such design. The Scanner achieved an optical deflection angle of more than eighty degrees at a resonance frequency of two thousand and six hundred Hz.
Lastly, chapter seven will present the conclusion and future work on the subject of the thesis, namely, MEMS scanners.