Method and system of determining field dependent aberrations

A method of determining field-dependent aberrations in an image field of an optical imaging system based on a measuring operation determining aberration data for a plurality of field points in the image field, the method comprising:

• defining a target grid comprising a plurality of target field points in the image field, wherein each target field point of the plurality of field points is a field point for which a level of aberration is to be determined;
• defining a measuring grid comprising a first subset of target field points of the plurality of target field points comprising all field points for which a level of aberration is to be determined in a measuring operation;
• performing the measuring operation, the measuring operation comprising measuring aberrations at all field points of the measuring grid to generate measured aberration data;
• defining an auxiliary grid comprising a second subset of target field points of the plurality of target field points comprising selected target field points of the plurality of field points not included in the measuring grid for which a level of aberration is to be determined in an aberration data generating operation;
• and
• performing the aberration data generating operation, wherein the aberration data generating operation is configured to generate aberration data for target field points of the auxiliary grid based on
• (i) knowledge of the optical imaging system and
• (ii) potential system-specific sources of aberrations.