Fig. 1: Experimental demonstration of JPD pixel super-resolution.
From: Pixel super-resolution with spatially entangled photons
a Experimental setup. Light emitted by a diode laser (405 nm) illuminates β-barium borate (BBO) crystal with a thickness of 0.5 mm to produce spatially entangled pairs of photons by type I SPDC. Long-pass and band-pass filters at 810 ± 5 nm (BPF) positioned after the crystal remove pump photons. A two-lens system f1−f2 images the crystal surface onto an object t, that is itself imaged onto the EMCCD camera by another two-lens system f3−f4. t is a grid-shaped amplitude object. Photon correlation width in the image plane is estimated as σ ≈ 13 μm and camera pixel pitch is Δ = 32 μm. b Intensity image, (c) JPD diagonal image and (d) sum-coordinate projection of the JPD. e Intensity image obtained using a camera with half pixel pitch i.e. 16μm. All images show the same spatial region of the object containing 10 grating periods. Coordinates are in pixels. f Spectra of the intensity image (solid red), diagonal image (dashed black), JPD sum-coordinate image (dashed blue) and intensity image acquired with a 16 μm-pixel-pitch camera (dashed red) obtained by performing a discrete Fourier transform to the corresponding image and averaging over the x-axis. g System modulation transfer function (MTF) obtained using the slanted-edge technique with an intensity image (solid red), a diagonal image (dashed black), a JPD sum-coordinate image (dashed blue) and an intensity image acquired using a 16 μm-pixel-pitch camera (dashed red). All frequency values are normalized to the same reference frequency k0 = 1/Δ.
