Laser Beam Position-Dependent PSD-Based Calibrated Self-Vibration Compensated Noncontact Vibration Measurement System

This paper explores the notion and efficacy of harnessing the advantages of position sensitive detector (PSD) in the paradigm of noncontact vibration measurements. The study peruses an innovative foray into the domain of calibrated vibration measurement systems, wherein a first-of-its-kind strategy has been explored to nullify the self-vibration effect of the PSD platform by incorporating a micro-elctromechanical system digital accelerometer. The self-vibration compensated system has been designed and experimentally validated through NI-CompactRIO. The proposed system has been calibrated with a single axis Brüel&Kjær piezoelectric accelerometer. The system was observed to yield a maximum absolute error of 0.34 Hz in the measuring frequency range of 20–600 Hz. Furthermore, the system was observed to effectively measure displacement in the range of 2.32–
$1300~\mu \text{m}$
with a maximum relative error of 2.7% across the span of gain settings varied at designated set of frequencies tested. Successive measurements yielded good repeatability characterized by a maximum standard deviation of
$1 ~\mu \text{m}$
. A commendable system linearity was also achieved for its intended range of measurement as characterized by a correlation coefficient of 99.8%. The accuracy and robustness of the noncontact PSD system coupled with its inherent simplicity of system integration establishes itself as a potent and cost-effective tool in the realm of vibration measurements of highly sensitive systems susceptible to microvibrations (<1 kHz) compared to its more expensive prevalent noncontact laser Doppler vibrometer counterparts. The developed system also exhibits pivotal significance in critical application areas where human involvement is not advisable.