406
5 Laser Specklometer, Speckle-Optical Diagnostics and Laser …
Fig. 5.21 PSD of vibrator oscillation with 30 Hz frequency and amplitudes: a 1.5 μm; b 3 μm,
c 6 μm obtained with the first illuminating–receiving head. Reprinted from [87] with permission
Dependence of spectral density of the scattered radiation on vibrator oscillations
on the frequency of 30 Hz with the amplitudes of 1.5, 3 and 6 μm is presented in
Fig. 5.22. The dependence was obtained with the laser specklometer.
It is worth mentioning that if the oscillation amplitude of the surface under study
increases then the amplitude of the main spectrum harmonic increases monotonously;
i.e., it adequately transmits information about changes of amplitude of vibration.
Determination of vibration amplitude was conducted at different levels of the
output signal of generator 12 (see Fig. 5.17), which corresponds to the determined
ideal values A V of vibration amplitude of the surface under study. It was determined
through registration and calculation using the laser specklometer of amplitude of the
first spectral harmonic A 1 in intensity fluctuation spectrum of dynamic speckle-field
obtained by means of time averaging of a random signal over 16 realizations of this
spectrum. The value of vibration amplitude measured with the certified laser Doppler
vibrometer was taken for the ideal value A V of the vibration amplitude.
5 Laser Specklometer, Speckle-Optical Diagnostics and Laser …
Fig. 5.21 PSD of vibrator oscillation with 30 Hz frequency and amplitudes: a 1.5 μm; b 3 μm,
c 6 μm obtained with the first illuminating–receiving head. Reprinted from [87] with permission
Dependence of spectral density of the scattered radiation on vibrator oscillations
on the frequency of 30 Hz with the amplitudes of 1.5, 3 and 6 μm is presented in
Fig. 5.22. The dependence was obtained with the laser specklometer.
It is worth mentioning that if the oscillation amplitude of the surface under study
increases then the amplitude of the main spectrum harmonic increases monotonously;
i.e., it adequately transmits information about changes of amplitude of vibration.
Determination of vibration amplitude was conducted at different levels of the
output signal of generator 12 (see Fig. 5.17), which corresponds to the determined
ideal values A V of vibration amplitude of the surface under study. It was determined
through registration and calculation using the laser specklometer of amplitude of the
first spectral harmonic A 1 in intensity fluctuation spectrum of dynamic speckle-field
obtained by means of time averaging of a random signal over 16 realizations of this
spectrum. The value of vibration amplitude measured with the certified laser Doppler
vibrometer was taken for the ideal value A V of the vibration amplitude.