Simplified model for design of tailored circularly symmetric quasi-Bessel beams

Due to its extended focal length and self-healing properties, Bessel beams are suitable for a variety of applications in science and technology. However, an ideal Bessel beam would carry an infinite amount of energy; hence, experimentally, only very good approximations known as quasi-Bessel beams (QBB) can be realized. QBB has several fundamental advantages over a Gaussian. Of particular interest is control over the intensity axial distribution and focal width of the generated beam, which can be tailored for specific application needs. There are numerous examples of this presented in the literature; however, the models are often complex and hard to generalize. Here, we combine existing physics into a simplified, intuitive, and easily implemented model for designing a circularly symmetric, yet axially tailored, QBB, illustrated with an axial top-hat beam as a specific example