High-resolution up-conversion imaging in the 10- <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mtext fontfamily="times">μ</mml:mtext> <mml:mrow> <mml:mi mathvariant="normal">m</mml:mi> </mml:mrow> </mml:math> band un

The long-wavelength infrared band exhibits significant utility in thermal signature acquisition, molecular spectral analysis, and other applications. The up-conversion detection technique enables effective signal transduction into the detection bandwidth of silicon-based photodetectors, facilitating high-sensitivity photodetection. We demonstrate high-resolution up-conversion imaging for incoherent thermal targets in the $10$-$\text{\ensuremath{\mu}}\mathrm{m}$ spectral regime. Furthermore, this work presents a derivation of analytical models characterizing depth of field and astigmatic aberration in up-conversion imaging systems, which show good agreement between theoretical and experimental results. The results demonstrate generalization to various up-conversion imaging systems, providing critical insights for their design and optimization.