Estimation of readout signal fluctuation in multi-layer index modulation

In micro-reflector optical disc systems, multi-layer index modulation distribution causes wavefront fluctuation in the light beam passing through the recorded layers. Generally, the Marechal's criterion 0.07lambdarms is widely used as a figure of merit for wavefront quality of a light beam for readout. However, due to the fine structure of the wavefront fluctuation by the recorded marks, the decay of readout signal is less comparing to the general case.