METHOD TO DETERMINE AMPLITUDE OF NANOVIBRATIONS BY SIGNAL OF LASER AUTODYNE

摘要

FIELD: measurement equipment.;SUBSTANCE: method to measure amplitude of nanovibrations ξ, consists in the fact that an object is illuminated with laser radiation, they convert radiation reflected from it into an electric (autodyne) signal, the signal is decomposed into a spectral row, and they measure the value of amplitude of the harmonic S_x at the frequency of object oscillation Ω. At the same time additional mechanical vibrations are imposed onto the object at the frequency Ω₁ with minimum amplitude, they measure the maximum value of the harmonic S_1max, at the frequency Ω₁ as the amplitude of additional mechanical oscillations increases, they increase the amplitude of additional mechanical oscillations until there are interference maxima and minima appear on the autodyne signal on the dedicated interval of time between points that correspond to extreme positions of object displacement, they calculate the ratio of time of decay t_dec of the autodyne signal to the time of its increase t_inc in the dedicated interval of time. In the case when the value t_dec/t_inc is more than 1, they calculate t_inc/t_dec, on the basis of the dependence t_dec/t_inc(C) or t_inc/t_dec(C) they determine the level of the external optical feedback C, they calculate S_x/S_1max, according to the dependence S₁/S_1max(ξ, S) with the previously determined C they find ξ.;EFFECT: higher accuracy of measurement of amplitudes of nanovibrations.;17 dwg, 1 tbl