An Inertial Uni-Axial Interferometer-Based Accelerometer for Harsh Environments

For high-impact devices, subsequent vibrations have as much influence on the deterioration of the mechanical structure as the impact itself. To mitigate the consequences of both impacts and resulting vibrations, it is crucial to accurately understand the peak acceleration and vibration frequencies that originate in the structure. In this article, a radiation tolerant opto-mechanical sensor based on an absolute measurement inertial accelerometer is presented. This method of measurement is chosen due to the viability of placing the readout electronics far from the highly radioactive environment that the sensor may be installed in. The designed accelerometer consists of a fixed aluminum frame with a built-in membrane that acts as a leaf spring. In the same membrane, a retro-reflector is attached which acts as a seismic mass. The retro-reflector reflects the light beam coming from the collimator lens placed on the frame. To prove its viability, the device has been tested under different conditions. First, the device is calibrated and validated using a high-frequency exciter. Second, a high-acceleration testbench is used to compare its output signal with a commercial accelerometer and verify its proper operation as well as its expected lifetime. The experimental results showed an average sensitivity of ${9} \times {10}^{-{4}}$ g/pm with reading measurements of up to 5000 g and a working bandwidth located between 50 and 800 Hz.