The invention relates to a method for the production of 4-benzaldehyd–oximes of general formula, where R1\u2550H, C1-6 alkyl or a CnF2n+1 group; R2\u2550C1-4 alkyl, X=E- or Z-OH; and Y\u2550O\u2014C1-6 alkyl, S\u2014C1-6 alkyl or O\u2014CH2CnF2n+1, where n=1, 2 or 3, which produces the target compounds of formula with high yield and selectivity. The thickness of each of the lenses constituting the lens array is adjusted such that the step difference at the boundaries between the lenses falls within a predetermined step difference. According to the invention the system configuration can be made simple, and wide LO and IF frequency bandwidths can be provided.