Spatial resolution element
= Spatial resolution element
{title2=$\Delta\vartheta\sim\lambda/D$}
A <spatial resolution element> is one independently resolved angular or spatial scale under a specified resolution criterion. For an ideal telescope of <diameter> $D$, its angular scale is of order $\lambda/D$ and its angular area of order $(\lambda/D)^2$. A <photodetector> <detector pixel> or <spaxel> can be smaller than a resolution element without adding independent spatial information.