Vibration Analysis and Measurement for Quartz Tuning Fork under Laser Irradiation

The trace explosive detection in airline security is still difficult.The principle of detecting the photo-acoustic signals produced by quartz tuning fork is analyzed,then the optical path is simplified with the propose to reduce the energy loss of laser.After the analysis of the amplitude of the quartz tuning fork and the signals produced by the quartz tuning fork,an experimental system is established and the amplitude-frequency characteristic curve of the quartz tuning fork irradiated by laser is acquired.In addition,the influence of the location of laser spot on the amplitude of the quartz tuning fork is measured.And it shows that the amplitude of the quartz tuning fork reaches the maximum when the laser spot is about 0.2mm above the bottom of the prongs of the quartz tuning fork,laser spot moves up along the prongs,the amplitude decreases gradually,and the fact that the amplitude of the quartz tuning fork is proportional to the laser energy is verified.It is expected to apply to standoff photo-acoustic spectroscopy detection.