Autodyne interferometry for range-finding under laser radiation wavelength modulation

Signals of Autodyne Sensors with Sinusoidal Frequency Modulation

“…Result analysis of the performed research shows that the frequency of the signal converted by the autodyne in the whole range of distances to the target object exactly corresponds to the frequency of signal obtained in the case of the homodyne system [1][2][3][4], [9][10][11]. It is proved that at small distances to the reflected object when τ << T a the obtained analysis results conform to results of previous investigations [24][25][26][27]. When C FB is commensurable with unity, substantial distortions of autodyne signals and appearance of higher harmonic components in the signal spectrum are observed.…”

“…They have general character and physical interpretation on the basis of the stepping method known from the theory of retarded systems. Thus, the obtained results, in our opinion, can be also used for signal calculation of AS made on the basis of semiconductor laser modules [25][26][27].…”

“…The analysis of timing and spectral diagrams in Figs 2(а) and 3(а) shows that results presented in the current paper for the case of r n = 0 completely correspond to the results of earlier FM AS signal research described in [24][25][26][27]. In these publications, the signal analysis was performed only for the first approximation of retarded impact functions when τ << T a .…”

“…These papers deal with different mathematical models of autodynes and various representations of impact functions of the proper reflected radiation on the autodyne oscillator. However, at present the equation solution for the developed FM AS model is obtained only for the first approximation of the retarded impact function, which is true under the following condition: τ << T a where τ is the delay time of the reflected radiation; T a is the period of the low frequency autodyne signal [24][25][26][27]. This inequation may be violated in practice.…”

“…Among the above mentioned modulation types, the frequency modulation (FM) has become the most popular [1,[23][24][25][26]. As in the usual SRR of the homodyne type, the linear and sinusoidal FM in AS found the widest application.…”