绿光LED产生无衍射Bessel光束

Non-diffraction bessel-like beam generated by green LED source

采用单色LED光源得到较理想的近似无衍射Bessel光束.文中从LED光源的时空相干性出发分析用单色LED灯珠产生Bessel光束的可能性,利用光阑提高光场的空间相干性得于实现.设计实验光学系统,让LED光源发出的光经过一套光学系统后透过轴棱锥,得到了近似Bessel光束,光束中心亮斑大小及最大无衍射距离均与理论计算所得相符,证明用LED光源也能够产生较理想的近似Bessel光束.最后讨论了光阑孔径对所产生Bessel光束质量的影响,发现光阑孔径增大时所得Bessel光束强度变大但截面光强明暗对比度下降.

Ideal Bessel-like beam was generated by monochromatic LED source for the first time. In this paper, the possibility of using monochromatic LED source to generate quite ideal Bessel-like beam was discussed from the angle of spatial and temporal coherence, then we knew it＇s possible if a diaphragm was involved to increase spatial coherence. Optical system was designed： light wave emitted from LED passed axicon after the optical system, and then Bessel-like beam was obtained, the size of center bright spots and non-diffraction distance wa：; accord well with the results which obtained from theoretical calculations, it demonstrated LED source could used to generate quite ideal Bessel-like beam. At last we discussed how the diaphragm＇s diameter affected the quality of Bessel beam, and found that the light intensity increased but contrast ratio of section intensity declined as the diaphragm＇s diameter enlarged.