Fig. 3: Static imaging and depth estimation of the ACEcam.

a Combined image of a laser spot from nine angles (from −90^o to 90^o in both the x and y directions at a step of 22.5^o). b Image of the logo of The Hong Kong Polytechnic University. c, d Depth estimation using the linear relationship between the point spread parameter σ and the reciprocal of the object distance u⁻¹. In (c), example images at four different distances u₁ = 3 mm, u₂ = 5 mm, u₂ = 7 mm, and u₄ = 9 mm are shown in the dotted box. In the image acquired at each distance, the grey values along four parallel lines (shown here in pink) in the x direction are analysed to calculate the mean value and the errors shown in (d). D_L is the distance between a point on the pink line and the upper boundary of an image. In (d), the inset shows the relative grey value distribution along one sample pink line in c. A low error range signifies a high reliability of ACEcam^’s depth estimation. e, Images of the letters ‘HK’ captured at three different polar angles relative to the centre of the camera: −50^o (top), 0^o (centre) and 50^o (bottom). f Schematic of an experimental setup to verify the nearly infinite depth of field of ACEcam. Objects A (circle) and B (triangle) are placed at angular positions of −40^o and 40^o. g Images of the circle and triangle patterns when the distance of the circle image is fixed at D_A = 2 mm and the distance of the triangle image varies from D_B = 2, 8 to 14 mm