Fig. 4From: Broadband Metallic Planar Microlenses in an Array: the Focusing Coupling Effect a The line-scanning profiles of light intensity across the focal spots of the 2 × 2 microlens array with the spacing of a = 0, 2, 4 μm, accompanied by the result of the isolated microlens. The coupling point E for the case of a = 0 μm can be clearly observed. b The derived focal length and FWHM of the focal spots as the spacing changes. The blue and green dashed lines represent the focal length and FWHM of the isolated microlensBack to article page