Rotary micro-electro-mechanical scanner for chip-level beam steering application

Abstract

Advanced systems, such as optical coherence tomography (OCT), light detection and ranging (LIDAR) and advanced driving assisting systems (ADAS), consist of various modules that are designed to meet stringent specifications. These modules require electronic, mechanical and optical components, which can make the system large, bulky, power hungry and expensive. With the use of micro-and-nano technologies, such modules can be miniaturized without compromising the system performance. Accordingly, the vision of this work is to develop compact and affordable components that can be used in advanced systems by leveraging the benefits of micro-electro-mechanical system (MEMS) technology and batch manufacturing. It can not only enable system miniaturization but also improve system performance in terms of power consumption. Polygon scanners are crucial devices for systems such as OCT and LIDAR that are widely used in biomedical imaging and environment sensing, respectively. Typically, these scanners consist of a metallic polygon mirror mounted on a DC micromotor, providing a range of high-speed operation depending upon the application. Current polygon scanners have a large footprint, consume a large amount of power and are heavy. Moreover, these features of polygon scanners become serious impediments when they are used in resource limited systems, such as LIDAR for navigation systems in drones or unmanned aerial vehicles. Consequently, there is a need for miniaturized polygon scanners that can accomplish similar functionality as conventional polygon scanners but that require less power and occupy a smaller real-estate. This research work is focused on exploiting MEMS technologies in order to realize chip scale versions of rotary polygon scanners through innovation in the integration of MEMS based micro-devices. A miniaturized polygon scanner requires a vertical micromirror mounted on a chip-level high speed rotary platform. Novel techniques to overcome the challenges of polygon scanner miniaturization using MEMS and micro-assembly technologies are presented. A micromotor based on electrostatic actuation was designed and fabricated using the PolyMUMPS process to implement the rotary platform. Various micro-polyhedron of different size for beam deflection were designed and fabricated using the PiezoMUMPS process and a simple integration technique was developed to mount these micro-polyhedrons onto the micromotor. The realized micro-scanner has an overall size of 1 mm3 and consumes power less than 1 milliwatts.

Date	1 Dec 2021
Original language	American English
Awarding Institution	École de technologie supérieure
Supervisor	Frédéric Nabki (Supervisor) & Michaël Ménard (Co-supervisor)