“…In equation 1, p is the period of fringe that results from interference of two beams, and λ is the wavelength of the laser, θ is the incidence angle, and n is the refractive index. Therefore, if θ reaches 90 degrees, up to half of the laser wavelength can be fabricated, and if n is higher, more small patterns can be made, but this is used only in special cases, and if normal laser interference lithography processes in the atmosphere, so n is 1 and θ is used between 0 and 90 degrees [6].…”