High resolution optical inertial sensor

High resolution optical inertial sensor

Inertial sensors [1] are widely used in the fields of seismology, exploration, controlling engineering, national defense, etc. However, traditional inertial sensors suffer from three major limitations: they have a limited resolution, they cannot distinguish between translation and rotation [2], and they are sensitive to the ambient noise (temperature, pressure, humidity, magnetic field, radiation…).

To address the limitations, we are developing interfeometric inertial sensors. The 1st generation was a compact and low-cost optical inertial sensor named NOSE [3].

The objective of this project is to improve the sensor resolution in a wider dynamic range. Meanwhile, the material and structure of the mechanical system will be studied to decrease the thermal noise and tilt-horizontal coupling. The figure below shows the new prototype, currently under development at PML. The figure also compares the sensitivity of this instrument with first choice instruments.

The picture below shows two other prototypes of optical inertial sensors recently developed at PML. On the left, the inertial mass motion is sensed by using a Bragg grating combined with a negative stiffness [5]. On the right, the inertial mass motion is sensed with an optical encoder, combined with a parallelogram mechanism for the guiding of the reflector [6].

References:

  1. Collette, C., Janssens, S., Fernandez‐Carmona, P., Artoos, K., Guinchard, M., Hauviller, C., & Preumont, A. (2012). Inertial Sensors for Low‐Frequency Seismic Vibration Measurement. Bulletin of the seismological society of America, 102(4), 1289-1300.
  2. Matichard, F., & Evans, M. (2015). Tilt‐free low‐noise seismometry. Bulletin of the Seismological Society of America, 105(2A), 497-510.
  3. COLLETTE C., NASSIF F., AMAR J., DEPOUHON C. and GORZA S.-P., Prototype of interferometric absolute motion sensor, Sensors and Actuators A: Physical, 2015, vol.224, 72-77.
  4. WATCHI J., DING B., MATICHARD F., COLLETTE C., Development of a high-resolution optical inertial sensor for sub-Hz seismic isolation, ISMA conference, September 2016 (Leuven, Belgium).
  5. COLLETTE C., FRANCQUI F., FUEYO L., Transducer with variable stiffness, No. EP15196716, 2015
  6. HELLEGOUARCH S. et al. Linear encoder based low frequency inertial sensor. International Journal of Optomechatronics. 10(3-4), 120-129, 2016.