Nonlinear absorption processes play a significant role in the ultra-short pulse behavior of thin film dielectric optics. The primary mechanisms are typically multiphoton absorption and photon tunneling, resulting in avalanche ionization and damage to the optic. Nonlinear absorption measurements provide an alternative to obtain an LIDT estimate without using destructive methods. By using an LCA-measurement to track the increased absorption of an optic with respect to the irradiation intensity, it may be possible to obtain an estimate of the LIDT. This absorption can be characterized by several theoretical models. Additionally, the effect of imbedded particles in the film are discussed.