\({\text{NA}} = \frac{{0.61\,\lambda }}{{\text{d}}}\)
Where \(\mathrm{d}=\) minimum sparaton between two points to be seen as distinct
\({\text{d}} = \frac{{0.61\,\,\lambda }}{{{\text{NA}}}} = \) \(\frac{{(0.61) \times \left( {5000 \times 10\,{{\text{m}}^{ - 10}}} \right)}}{{1.25}}\) \( = 2.4 \times {10^{ - 7}}{\text{m}}\)
\( = 0.24\,\mu m\)