Q-spoiling

For our problem the breakin gof the caustics removes the bound on the fluctuations in sin χ and allows the classical escape process and Q-spoiling of the WG modes.

Source: wiktionary

Second, as mentioned above, hidden modes with low φ (i.e., low mode order) can become observable with small amounts of Q-spoiling.

Source: wiktionary

The significant Q-spoiling observed is in part due to the refractive loss in the contact area between the QW sample and the sphere since the QW sample has an index of refraction greater than that of the fused silica microsphere and is also in part due to the scattering loss occurring in the contact area.

Source: wiktionary