A precise method for analyzing Bessel-like beams generated by broadband waves

The current study proposes spectrum analysis, which is a novel analytical method proposed for the first time, for analyzing Bessel-like beams generated by broadband wave. The main idea is to decompose the consecutive spectrum into an incoherent superposition of a series of different wavelengths. Integrating spheres play a significant role in spectrum analysis and a series of wavelengths matched with relative intensity can be read according to the spectrum measured by an integral ball. Moreover, the Sellmeier dispersion equation, which indicates that the refractive index can be matched with wavelength, is also employed. Combining with the Fresnel diffraction integral formula, the distribution of fields behind an axicon is obtained. Two broadband sources, including a light-emitting diode (LED) with a narrow band and a halogen lamp with a broad band, are used to generate a Bessel-like beam. The experimental results fit well with the theoretical analysis.