  Deviation from perfect conical dispersion in Dirac materials, such as the
presence of mass or tilting, enhances control and directionality of electronic
transport. To identify these signatures, we analyze the thermal derivative
spectra of optical reflectivity in doped massive tilted Dirac systems. The
density of states and chemical potential are determined as preliminary steps to
calculate the optical conductivity tensor at finite temperature using thermal
convolution. Changes in reflection caused by temperature variations enable
clear identification of critical frequencies in the optical response. By
measuring these spectral features in the thermoderivative spectrum, energy gaps
and band structure tilting can be determined. A comparison is presented between
the spectra of various low-energy Dirac Hamiltonians. Our findings suggest that
thermal difference spectroscopy holds promise as a valuable technique for
probing interband transitions of 2D Dirac fermions
