On the nonlinearity of a tuning fork

Tuning fork experiments at the undergraduate level usually only demonstrate a tuning fork's linear resonance. In this paper, we introduce an experiment that can be used to measure nonlinear frequency response curve of regular fork. Using double-grating Doppler interferometry, achieve measurement precision oscillation amplitude in range microns. With experimental setup, observe behaviors fork, such as softening and jump phenomenon. This provides integrated for intermediate-level students basis senior research projects.