A method for measuring acceleration based on the use of the fast-discrete Fourier transform algorithm is proposed. The simulation of the spectrum of the self-mixing signal at the uniformly accelerated motion of the reflector is carried out. The relationship of low-frequency and high-frequency components of the self-mixing signal spectrum with the object acceleration value is shown. The measurement of uniformly accelerated motion of an object on the spectrum of a self-mixing signal is experimentally realized. The accelerated motion of the reflector was carried out using a signal generator built into the laboratory station of the Ni ELVIS virtual instruments. The results of measuring the motion of piezoceramics with the acceleration given by the quadratic law of voltage change on it are presented. The results of calculation of acceleration on the spectrum of the self-mixing signal for 26 μm/s2 are presented. The resolution of the proposed method was estimated by measuring the frequencies of neighboring spectral components and amounted to 500 nm/s2.
Laser self-mixing interferometry of absolute distances is represented by the method of frequency modulation of supply current of the laser diode (FMCW technique). The advantages of the triangular wave modulation method in combination with the use of the frequency of the self-mixing signal spectrum have been shown. The advantages of the harmonic wave modulation method in combination with the use of the some various amplitudes of the self-mixing signal spectrum have been shown were shown also. The advantages of the harmonic wave modulation method in combination with the use of different amplitudes of the spectrum of self-mixing signals are shown. The equipment includes a frequency-modulated semiconductor self-mixing laser diode RLD-650 on quantum-size structures with a diffraction-limited single spatial mode with a wavelength of 654 nm. The results of computer simulation showed that the accuracy of determining the distance at the harmonic wave modulation decreases with increasing the distance to the measured object. But at small distances, its value is much smaller than at the triangular wave modulation of laser radiation.