Realization and metrological characterization of a compact high-resolution pendulum tiltmeter

This work describes the design, realization, and testing of a novel compact tiltmeter model, which is based on a simple free pendulum and optical detection. Two equal prototypes were built and metrologically characterized against each other. Various mechanical and electronic noise sources were first analyzed theoretically, in order to identify the expected contributions to resolution and long-term stability. The stability of the prototypes was then measured and characterized with the Allan variance as a function of averaging time. Experimental results confirm the theory. The best measured resolution is 300 prad and is obtained with an averaging time of 300 s. The dynamic range is ±300 μrad. Such values are suitable for the needs which stimulated the development of the device; however, improvements are possible and directions for the realization of a better version are indicated.