Mid-IR nonlinear pinhole camera captures 3D images without lenses down to low light 1.5 photons per synchronized ultrafast pulse

https://www.eurekalert.org/news-releases/1097545

"chirped-period crystal accepts IR from many directions/ converts to visible, upconversion detection suppresses noise enabling low light conditions... 0.20 mm pinhole radius produces sharp details in image targets: 11 to 19 cm away, across all distances at 3.07 μm mid-IR confirming large depth range, up to 35 cm away demonstrating large depth of field, µm-level axial precision... relatively complex/ bulky laser setup should, with further research, become far more compact/ easier to deploy"