People try to recover true 2D brightness distribution information through incomplete information at radio wavelength band. So the quality of generated images is treasured. People always try to gain the best result by low cost. So a problem about how to get the best image with an interferometric array at the limited cost has been concerned by radio astronomers. Generally speaking, two problems should be considered in interferometric array configuration. The first is that how to assess an interferometric array or what is a ‘good’ array. The second is that how to design or optimize arrays with a given assessment criterion or how to get a ‘good’ array. Bonton indicated ‘For two dimensional arrays, there is no exact solution, and it is even difficult to specify an optimization criterion’ in 1999. However, we hold the opinion that how to assess an array is a fundamental problem for array configurations. It determines the goal and direction of designing and optimizing. Both design and optimization are only applications of assessment criterion. Also they are just superstructures of assessment criterion. Image quality assessment technology is introduced to assess interferometric arrays. Including the existing assessments of interferometric array, four categories of array assessment methods are concluded: assessing the UV coverage directly, assessing the UV coverage related to observing objects, assessing the imaging quality related to observing objects and assessing the imaging quality directly. A specific method in each category is proposed. All assessments are used to design or optimize interferometric arrays, especially the early-stage study of Solar Low Frequency Array.
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