### Romanov V.G.

## Inverse phaseless problems that use vawe interference

INVERSE PHASELESS PROBLEMS THAT USE THE VAWE INTERFERENCE

V.G. Romanov

We consider the inverse problems for diﬀerential equations with complex-valued solutions in which the modulus of a solution to the direct problem on some special sets is a given information in order to determine coeﬃcients of this equation; the phase of this solution is assumed unknown. Earlier, in similar problems the modulus of the part of a solution that corresponds to the ﬁeld scattered on inhomogeneities in a wide range of frequencies was assumed given. But this is physically much more diﬃcult to measure the modulus of a scattered ﬁeld than that of the full ﬁeld. In this connection the question arises how to state inverse problems with the full-ﬁeld measurements as an information. The present talk is devoted to the study of this question. We propose to take two plane waves moving in opposite directions as an initiating ﬁeld and to measure the modulus of a full-ﬁeld solution relating to interference of the incident waves. We consider also the problems of recovering the potential for the Schrodinger equation and the permittivity coeﬃcient of the Maxwell system of equations corresponding to time-periodic electromagnetic oscillations. For these problems we establish uniqueness theorems for solutions. The problems are reduced to solving some well-known problems.

The work was supported by the Russian Foundation for Basic Research (Grant 17–01–00120).

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