Sidelobe reduction of tightly focused radially higher-order Laguerre-Gaussian beams using annular masks.
We report the reduction of sidelobes in tight focusing patterns of radially higher-order Laguerre-Gaussian (LG) beams with nonhelical phase structures. Numerical calculations based on the vectorial Debye theory reveal that a class of annular masks reduces sidelobes in the tight focusing patterns only for radially even-order LG beams. The present scheme produces small focal spots beyond the diffraction limit suitable for application to scanning microscopy, laser fine processing, etc.
Ohtake
Yoshiyuki
Y
Hamamatsu Photonics K K, Central Research Laboratory, Hirakuchi, Hamakita-Ku, Hamamatsu 434-8601, Japan. ohtake@crl.hpk.co.jp
Ando
Taro
T
Inoue
Takashi
T
Matsumoto
Naoya
N
Toyoda
Haruyoshi
H