To develop effective disruption mitigation scenarios for future high-current tokamaks, it is essential to have measurements of plasma state with high spatial and temporal resolution in existing devices. Density is an important quantity for hydrogenic shattered pellet injection (SPI) studies where high electron density can suppress runaway electron beam formation by increased collisional drag and dilution cooling. At ASDEX Upgrade the line-integrated electron density has been measured by the DCN-laser interferometer (probing at 195 μm) and a two-colour CO2/HeNe-laser interferometer (probing at 10.6 μm) but neither have been able to reliably measure density during disruption studies. The DCN interferometer suffers beam refraction due to the strong density gradients and the CO2 interferometer suffers vibrational noise. Both interferometers are subject to "fringe jump" ambiguities of the phase angle, resulting in incomplete density tracking. Unlike these Mach-Zehnder-class interferometers, a dispersion interferometer operate with a single beam path where nonlinear crystals generate second-harmonic co-linear probing beams for true measurements of plasma dispersion free of vibrational noise. Dispersion interferometers have been installed at stellarators and tokamaks, such as W7-X (Brunner et al 2018} and EAST (Liu et al 2024). We present the implementation of a dispersion interferometer at ASDEX Upgrade using a fundamental and second-harmonic wavelength of 10.6 μm and 5.3 μm, respectively. The reduced wavelength becomes more resilient to beam refraction due to large density gradients perpendicular to the line of sight. Furthermore, at a shorter wavelength we have a density-to-phase relationship of $7.43 \cdot 10^{19}$ per 2π rad, larger than typical flattop density, meaning fringe jumps should be fewer and easier to correct for. From scenarios of SPI into healthy and unhealthy plasmas with varying D2/Ne mixtures and pellet shattering dynamics we have a large quantity of highly time-resolved measurements showing reproducible dynamics between similar pellet types. The diagnostic offers a rich field of new datasets for future model validation.