New physical details inherent in the non-collinear two-phonon Bragg light scattering controlled by ultra-high frequency elastic waves of finite amplitude are studied in wide-aperture crystals exhibiting moderate linear acoustic losses. Recently, it had been demonstrated that Bragg regime of light scattering exhibits the specific acousto-optical nonlinearity with a set of unit-level maxima. Now, additionally to our previous analysis, we present an advanced analytical description of this phenomenon in the amplitude and frequency domains; and what is more, we orient it mainly at the second unit-level maximum. This nonlinearity together with the linear acoustic losses in an acousto-optical cell produces a new effect of nonlinear apodization. The light beam, leaving the cell, can suppress side lobes and grow the dynamic range within potential optical spectrum analysis. After that we characterize comprehensively an acousto-optical cell, made of calomel and working within the second maximum of two-phonon light scattering, as a dispersive optical component. Finally, the results of our proof-of-principal experiments with the calomel-made cell, operating in the chosen regime, are presented and discussed.