SBIR-STTR Award

The demands of next generation missile systems call for both a smaller overall weights and form factor and better performance for assured position, navigation, and timing. Commercially available MEMS based IMUs offer attractive SWaP-C specifications but suffer from a lack of precision and accumulate too much error over time. Interferometer-based optical pickoffs are a promising solution to the noise limits of current sensors and may lead to high-performance MEMS accelerometers. EngeniusMicro, LLC has previously demonstrated promising fabrication technology to realize optical pickoff for MEMS accelerometers. In this proposal we propose to develop fabrication processes to meet critical dimension requirements and tolerances necessary and to realize a high-yield, high-throughput manufacturing process for optical pickoff accelerometers. We aim to address key challenges in making self-aligned optical components; precise placement and orientation of reflectors, and precise control over reflector geometry. Our new design features a fabrication process created to optimize the reflector and self-alignment structures with minimal manual alignment and handling. We will capture the dynamics and repeatability of the fabrication with a DOE study to understand process control requirements. After defining the systematic and stochastic effects driving fabrication, we will implement a design-based approach to create a released MEMS accelerometer with a self-aligned optical pickoff.

Sensitivity enhancement of optical inertial sensors has shown to be possible by using anomalous dispersion media. Although the scale factor and signal to noise ratio can be greatly improved by exploiting anomalous dispersion the signal extinction is a major issue. Our previous effort demonstrated critical components to achieve millimeter scale optical cavities with anomalous dispersive gas media, and these efforts confirmed that shorter path lengths enabled enhancement with greatly reduced absorption. Our previous efforts also demonstrated critical components and processes to align and assemble microscale optical components to exploit the anomalous dispersion effect. This Phase II proposal will develop compact and robust implementation of a micro optical cavity an anomalous dispersive gas media and develop a mm-scale inertial sensor to utilize this technology. The goal is not only to demonstrate the benefits of anomalous dispersion for inertial sensors, but also create a robust, passively-aligned microfabricated cavity, eliminating much of the complexity inhibiting production and manufacturability. Several technologies are leveraged to accomplish this including spherical and 45° micromirrors, kinematic constraints using V-groves, and precise bonding at the die level. The dispersive media cell design will leverage dispensers that eliminate the need for highly specialized high-vacuum equipment and ensure the quality of the media cell. The integration of a microoptical cavity with dispersive media will enable shorter path lengths and less attenuation in the optical path.