Laser Doppler technology is widely used in precision vibration measurement such as voice acquisition. The fundamental of voice acquisition is to detect the vibration of targets induced by sound wave using a Laser Doppler voice acquisition system, and then demodulate the voice signal from interference signal. Therefore the target’s vibration characteristics will be the principal factor influencing the effect of voice acquisition. In this paper, we focus on the plane structure’s vibration characteristics caused by voice. There are mainly two parts in this paper, simulation and experimental verify. In simulation, the finite element method is used. The Finite Element Analysis method is widely used in material properties analysis, dynamic analysis, and acoustic analysis. Through finite element analysis method, the plane structure models of thick smooth aluminum are established by ANSYS. Then the frequency responses of different constraints are compared. The Laser Doppler voice acquisition system is applied to test and verify the simulation results. The response characteristics of aluminum board under different excitation frequency are measured. The experimental results and simulation results are compared to verify the correctness and reasonableness of simulation. At the same time, this provides theoretical guidance for Laser Doppler voice acquisition system to choose targets and improve voice acquisition performance.
A novel acoustical-vibration signal detection system based on laser Doppler is proposed. The system is based on the
M - Z interferometer optical system, and used more adaptive piezoelectric ceramics modulation and demodulation
system to restore signal. The whole system satisfies the requirements of non-contact, remote, high sensitivity and
anti-interference. It has the advantages of strong stability, compact light path, low cost and easy miniaturization
compared with heterodyne interferometer based on Acoustical Optical Modulator (AOM). At last the influence of the
laser power fluctuations (frequency instability and amplitude instability) on the system is analyzed theoretically.
The characteristic of several night imaging and display technologies on cars are introduced. Compared with the current
night vision technologies on cars, Range-gated technology can eliminate backscattered light and increase the SNR of
system. The theory of range-gated image technology is described. The plan of range-gated system on cars is designed;
the divergence angle of laser can be designed to change automatically, this allows overfilling of the camera field of
view to effectively attenuate the laser when necessary. Safety range of the driver is calculated according to the theory
analysis. Observation distance of the designed system is about 500m which is satisfied with the need of safety driver
Based on the semiconductor laser whose spectral line with width is compressed to be less
than 1.2Mhz, a system was designed to measure and improve the amplitude and frequency of the
real-time microvibration with sinusoidal modulation. real-time microvibration measurement was
executed without alignment problem in the interferometry; and low-frequency disturbance of
environment could be eliminated. Suggestions were also given to consummate the system. The system
also has resistance against the low frequency disturbance of the environment.