## What is/are Amplitude Masks?

Amplitude Masks - Osuch, "Harmonic analysis of fiber Bragg gratings written using apodized phase and amplitude masks", Opt.^{[1]}With fractal amplitude masks of the Sierpinski carpet and Sierpinski triangle, we theoretically and experimentally present the diffraction properties and applications of spatially structured optical fields, including the vector optical field, vortex optical field, and vortex vector optical field.

^{[2]}For large pitches, amplitude masks are shown to give the best resolution; whereas, for small pitches, phase masks are superior because the required exposure time is shorter.

^{[3]}After developing the theoretical basis of SODI, we demonstrate the second-order resolution improvement experimentally using phase masks and binary amplitude masks with only 8 frames.

^{[4]}As a proof of concept, we demonstrate multiwavelength holograms, multiwavelength waveplates, and polarization-insensitive 3D holograms based on phase and amplitude masks.

^{[5]}Both, one-dimensional (1D) and two-dimensional (2D) Bessel-like beams with different topology of 2D beam cross-sections are formed from Gaussian laser beams using the amplitude masks with rectangular and annular apertures.

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