A random phase plate is an optical element that is machined from fused silica or optical glass into a structure with a random phase distribution and small height variations. The random height variations of these surface nano-retardations generally follow a Gaussian or uniform distribution and introduce a statistically random phase delay to the incident laser. The central role of the random phase plate is to achieve beam homogenization, uniform scattering, disruption of beam space coherence and wavefront shaping. By destroying the coherence of the beam and diffraction effects, a top-hat light intensity distribution can eventually be generated in the far field or in the focal plane of the lens. It is generally used in laser homogenization, beam decoherence, high quality imaging projection and random scatter generation for laser material processing, laser display, and bio-imaging applications.