Figure 5. Dependence of focusing intensity (Im), spot size (FWHM) along the x direction in the focal plane, depth of focus (DoF), and focal length (f) on the etch depth. The solid and dot curves respond to the cases of light incident from the FZP’s substrate and structure sides, respectively

From

The Focusing Characteristics on the Binary Phase Sub-wavelength Fresnel Zone Plate

Taikei Suyama

International Journal of Physics. 2019, 7(3), 86-90 doi:10.12691/ijp-7-3-3