P044-0017
Micro Fabricated Optical Seismometer "FROSTY"

Friday, 11 December 2020
Poster
Dominique Fourguette1, Jaime Da Silva2, Volkan Otugen2, Elie Ramon Salameh3 and Greg Ritter4, (1)Michigan Aerospace Corporation, Ann Arbor, MI, United States, (2)Southern Methodist University, Dallas, TX, United States, (3)Southern Methodist University, Mechanical Engineering, Dallas, TX, United States, (4)Michigan Aerospace Corporation, Ann Arbor, United States
Abstract:
As part of NASA’s COLDTech program, a micro-fabricated optical seismometer prototype was developed for measuring seismicity on Europa and other icy bodies. In this paper, we describe the seismometer concept, the development of the prototype and test results.

The seismometer uses optical fibers and waveguides to communicate between the sensor and the attending electronics and laser diode. As such, the electronics can be located in a temperature-controlled section of the lander at a considerable distance from the sensor. A light bridge can be used to isolate the electronics from the sensor on the ground. The size of the seismometer is estimated to be less than one cubic centimeter, and that of the electronics less than 20 cubic centimeters, the mass to be less than 0.2 kg, and the power requirements to be less than 90 mW with COTS opto-electronic components (3 axis). The signal processing consists of analyzing the transmission signal of the resonator and requires small computing resources (Raspberry 4 for instance).

The seismometer sensing element is an optical whispering gallery mode (WGM) resonator. WGM resonances are observed as sharp dips in the transmission spectrum at the output of the waveguide[1]. The optical resonator is a small dielectric cavity with circular shape (such as a disk, ring or a racetrack). The WGM (also known as morphology dependent resonances, MDR[2]) are the optical modes of the resonator and are extremely sensitive to changes in the morphology of the resonator. Therefore, any minute change in the resonator morphology caused by a perturbation of an external physical condition can be determined precisely by observing WGM shifts in the transmission spectrum. Details of the seismometer prototype developed during this project, as well as the next generation configuration and model results, will be presented.

[1] Ioppolo T., Ayaz U.K. and Ötügen M.V., “High-resolution force sensor based on morphology dependent optical resonances of polymeric spheres,” J. Appl. Phys. 105 013535 (2009)

[2] Benner, R.E., Hill, S.C., “Morphology-dependent Resonances,” in Optical effects Associated with Small Particles, P.W. Barber and R.K. Chang, Eds., Advanced Series in Applied Physics, World Scientific (1988)

<< Previous Abstract | Next Abstract >>