Deformation of laser reflection surface in primary calibration of accelerometers

Abstract In international comparisons of single-ended (SE) accelerometer calibrations, a significant issue has been the relative motion between the laser measurement position and the reference surface of the accelerometer. One cause of this relative motion is deformation of the adapter to which the accelerometer is attached. In this study, to quantify and elucidate the mechanism of this adapter deformation, multipoint vibration measurements were conducted using multiple adapters with different load masses, Young’s moduli, and thicknesses. The results demonstrated that the magnitude of the deformation is proportional to the square of the vibration frequency, proportional to the load mass, inversely proportional to the Young’s modulus, and inversely correlated with the thickness. These findings indicate that the quasi-static deformation induced by the inertial force of the accelerometer is the primary cause of adapter deformation. For a stainless steel adapter combined with a Brüel & Kjær type 8305-001 accelerometer, a radial deformation factor of (−1 to −1.7)%/mm was measured at 20 kHz. These findings contribute to ensuring international equivalence in the primary calibration of SE accelerometers.