We study potentials of a new wide-aperture crystalline calomel-made acousto-optical cell. Characterizing this cell is non-trivial due to the chosen regime based on an advanced non-collinear two-phonon light scattering. Recently revealed important features of this phenomenon are essentially exploited in the new cell and investigated in more detail. These features can be observed simpler in tetragonal crystals, e.g. calomel, exhibiting specific acousto-optical nonlinearity caused by the acoustic waves of finite amplitude. This parametric nonlinearity manifests itself at low acoustic powers in calomel possessing linear acoustic attenuation. The formerly identified additional degree of freedom, unique to this regime, is exploited for designing the cell with an eye to doubling the resolution due to two-phonon processes. We clarify the role of varying the central acoustic frequency and acoustic attenuation using that degree of freedom. Then, the efficiency of calomel is exploited to expand the cell’s bandwidth at the cost of its efficiency. Proof-of-principle experiments confirm the developed approaches and illustrate their applicability to innovative technique of optical spectrum analysis with the improved resolution. The achieved spectral resolution 0.205 Å at 405 nm and the resolving power 19,800 are the best to our knowledge for acousto-optical spectrometers dedicated to space or airborne operations.