High NA Lens Axicon Research Articles

Tight Focusing of Double-ring-shaped Azimuthally Polarized Beam Using High NA Lens Axicon

Tight Focusing of Double-ring-shaped Azimuthally Polarized Beam Using High NA Lens Axicon

Creation of super-long bright channel using high NA lens axicon with dedicated multibelt binary phase mask

We provide a theoretical approach to use a multibelt binary phase mask in combination with a high numerical aperture lens axicon to achieve a subwavelength focal spot with large uniform focal depth when illuminated by an azimuthally polarized Laguerre–Gaussian beam. The intensity distributions are derived and evaluated based on the vector diffraction theory. Here we report a new method that generates a transversely polarized light beam with sub diffraction beam size (0.384 \(\lambda \)) that propagates without divergence over a long distance (of about 14 \(\lambda \)) in free space. The author expect such investigation is worthwhile for the applications of the optical manipulation, optical microscopy and optical micromachining.

Tight focusing of partially coherent radially polarized beam with high NA lens axicon

Tight focusing of radially polarized partially coherent vortex beam over a high numerical aperture lens axicon system is introduced and its propagation properties are studied based on vectorial Debye theory. The effect of propagation parameters on the intensity distribution, the polarization property and the coherent property of the beam is illustrated analytically and numerically. It is shown that the correlation length and maximal NA angle has a significant influence on the intensity profile.

Focus shaping of tightly focused TEM11 mode cylindrically polarized Laguerre Gaussian beam by diffractive optical element

We study the focus shaping of tightly focused TEM11 mode cylindrically polarized Laguerre Gaussian beam with high numerical aperture lens axicon system is investigated theoretically by vector diffraction theory. The intensity pattern at the focus can be tailored by appropriately adjusting the rotation angle. We show that the high NA lens axicon system can generates a sub wavelength focal spot, focal hole, focal splitting and flat-topped focal shapes with extended depth of focus.

Focal shift in radially polarized beam with high NA lens axicon by using radial cosine phase wavefront

Focal shift in radially polarized beam with radial cosine phase wavefront are investigated theoretically by vector diffraction theory. The wavefront phase distribution is cosine function of radial coordinate. Simulation results show that when the radially polarized beam with radial cosine wavefront phase is focused, the focal pattern differs considerably with frequency parameter in the cosine function term. On increasing C, focus can shift along optical axis and focal pattern changes remarkably. Focus may move in different direction under different condition. Focal shift distance fluctuates on increasing C, and fluctuation amplitude also increases simultaneously. In addition, focal shift direction can also be adjusted by changing frequency parameter in cosine function.

Generation of a strong uniform transversely polarized nondiffracting beam using a high-numerical-aperture lens axicon with a binary phase mask

We present a theoretical approach to generate a nondiffracting beam with extended depth of focus (DOF) and a smaller focal spot along the optical axis, by tight focusing of an azimuthally polarized beam with a circular symmetrical binary phase mask and an interference effect over a high-numerical-aperture (NA) lens axicon system. We find a general azimuthal diffraction integral for the circularly symmetric binary phase mask and examine it in two special cases: a high-NA lens and a high-NA lens axicon. The azimuthally polarized beam remains well behaved in both cases. We verify that the longitudinal component generated by azimuthally polarized illumination produces the narrowest spot size for a wide range of geometries. Finally, we discuss the effects of tight focusing on a dielectric interface and provide some ideas for circumventing the effects of the binary phase mask interface and even utilize them for spot size reduction.

Tight focusing of generalized cylindrical vector beam with high NA lens axicon

Focusing properties of the generalized cylindrical vector beam with high numerical aperture lens axicon system is investigated theoretically by vector diffraction theory. Results show that intensity distribution in the focal region can be tailored considerably by appropriately adjusting the polarization angle. Peak-centered, donut and flat top focal shapes with extended focal depth, potentially useful in optical tweezers, material processing and laser printing can be obtained using this technique.