In this paper, we upconvert images provided by 1.5 μm collimated continuous wave lasers illuminating resolution targets and small objects. Using a 2.7 nm wide pump spectrum at 1064 nm, we resolve 56x64 spatial elements whereas we obtained only 16x19 spatial elements with a narrow spectrum pump laser at 1064 nm with the same beam diameter and 8x8 spatial elements with a 0.5 mm thick crystal. These results are compatible with long range target recognition. A laboratory scale experiment of active imaging of diffusive objects is shown as an illustration.
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Romain Demur, Arnaud Grisard, Eric Lallier, Luc Leviandier, Loïc Morvan, Nicolas Treps, Claude Fabre, "Increasing image resolution in near-infrared to visible upconversion detection for long-range active imaging," Proc. SPIE 10677, Unconventional Optical Imaging, 1067703 (24 May 2018);