Fig. 5: Cross-correlation operation.
From: Single-layer spatial analog meta-processor for imaging processing
a The input image consisting of the square #1 with l11 = l12 = 60 mm and the square #2 with l21 = l22 = 25 mm at f1 = 100 mm. b The reference image of the square #1. c The phase profile (left) and the amplitude distribution (right) on the 60 × 80 Huygens’ metasurface as the physical block of the reference square #1. d Theoretical calculations (left), numerical simulations (middle) and experimental results (right) of the normalized electric field intensity distribution at the output focal length f2 = 100 mm and 10 GHz working frequency for pattern recognition of the square #1. e The cross-correlation operation between the input two-square sequence and the reference image containing one, two or three rectangular patterns with w1 = 70 mm (named as ①,②,③ respectively). Besides, The normalized intensity of output electric field along x-axis are demonstrated at focal length f1 = f2 = 600 mm and 10 GHz working frequency for sequence alignment.
