Methods, systems and computer program products for characterizing structures based on interferometric phase data

A computer program product for identifying variations in an index of refraction of a sample from optical interferometric data comprising:

• a non-transitory computer readable medium having computer readable program code embodied therein, the computer readable program code comprising:
• computer readable program code configured to obtain a plurality of broadband interferometric complex optical profiles of a sample as a function of depth in an axial direction, each of the plurality of interferometric complex optical profiles comprising a reference signal propagated through a reference path and a sample signal reflected from a sample reflector in the axial direction, wherein the complex optical profiles include magnitude data and phase data as a function of depth;
• computer readable program code configured to select at least one axial position corresponding to at least a portion of the structure;
• computer readable program code configured to determine phase variations between phase data of the plurality of interferometric complex optical profiles at the selected axial position;
• and
• computer readable program code configured to identify a variation in an index of refraction of the sample based on the phase variations of the phase data at the selected axial position.