a control system and method are provided for use in managing optical measurements on target structures . the control system comprises : data input utility for receiving input data indicative of a size of a target structure to be measured and input data indicative of illumination and collection channels of an optical measurement system ; data processing utility for analyzing the input data , and an interplay of point spread functions of the illumination and collection channels , and determining data indicative of optional tailoring of apertures to be used in the optical measurement system for optimizing ensquared energy for measurements on the given target structure , the optimal tailoring composing at least one of the following : an optimal ratio between numerical apertures of the illumination and collection channels ; and an optimal orientation offset of physical apertures in the illumination and collection channels .