Arbitrary focusing lens by holographic metasurface

In this paper, an ultrathin metalens has been proposed based on a holographic metasurface that consists of elongated apertures in 40 nm gold film, which exhibit intriguing properties such as on-and off-axis focusing and also can concentrate light into multiple, discrete spots for circularly polarized incident lights. First, the spatial transmission phase distributions of the designed metalens with arbitrary focusing can be obtained by computergenerated holography. Then, the discrete phase distributions can be continuously encoded by subwavelength nanoapertures with spatially varying orientations in gold film. The simulation results show that our designed metalens can work efficiently for different types of focusing. Finally, our metasurface shows superior broadband characteristics between 670 and 810 nm, and the corresponding focal lengths of the designed lenses also can be efficiently modulated with the incident lights at different wavelengths.

Focusing Properties of Partially Coherent Controllable Dark-Hollow Beams through a Thin Lens

Analytical propagation formulas are derived for partially coherent controllable dark-hollow beams （CDHBs） through a thin lens based on the generalized Huygens-Fresnel integral. The expressions of the position for maximum irradiance on-axis and the relative focal shift are evaluated by the analytical propagation formulas. Our numerical results show that both the relative focal shift and the effective beam width of focused partially coherent CDHBs are mainly determined by the initial transverse coherence width 6g and the Fresnel number Nw, which are also affected by the changes of both the dark-size adjusting parameter p and the order N of CDHBs.

Design and fabrication of one-dimensional focusing X-ray compound lens with A1 material

A method based on Fourier spectrum analysis for predicting the performances of the X-ray compound lenses is briefly introduced, the theoretical result obtained is the same as that of Fresnel-Kirchhoff approach. A kind of technique named moulding is developed for fabricating the one-dimensional (1D) compound X-ray lens with Al material and the fabrication process is presented. In addition, a two-time coating method is used to improve the numerical apertures of the compound lenses. Furthermore, the focusing performance of the Al compound X-ray lens under the high energy X-rays is measured.

A method based on diffraction theory for predicting 3D focusing performance of compound refractive X-ray lenses

A method based on the diffraction theory for estimating the three-dimensional (3D) focusing performance of the compound refractive X-ray lenses is presented in this paper. As a special application, the 3D X-ray intensity distribution near the focus is derived for a plano-concave compound refractive X-ray lens. Moreover, the computer codes are developed and some results of 3D focusing performance for a compound refractive X-ray lens with Si material are shown and discussed.

A theoretical method based on Fourier spectrum analysis for the focusing performances of the X-ray compound refractive lenses

It is important to predict the intensity distribution in focusing plane for designing the X-ray compound refractive lenses. On the basis of analyzing the structure of X-ray compound lenses and comparing it with Praunhofer diffraction system, it is concluded that the X-ray focusing system can be regarded as a kind of Praunhofer diffraction system. Therefore, a method based on Fourier spectrum analysis is presented to predict the intensity distribution in the focusing plane for the X-ray lenses. A brief analysis on the relationship between the parameters of X-ray lenses and their focusing performance is also given in this paper.

Design of double-zone aspheric diffractive intraocular lens with extended depth of focus

A double-zone aspheric diffractive intraocular lens （IOL） was designed and manufactured aiming to regain a continuous range of clear vision for pseudophakic presbyopia. After obtaining the IOL structure parameters through optimization based on an aphakic model eye, its imaging performances were analyzed in the model eye. The modulation transfer function at 50 cycles/mm remained above 0.29 within ±5° field of view for object distance ranging from 6 to 0.66 m. In addition, the imaging qualities are robust for pupil changes, polychromatic light, and different corneal asphericities. The manufactured IOL exhibits the abilitv to extend depth of focus.

Tuning the fields focused by a high NA lens using spirally polarized beams(Invited Paper)

We show the power of spirally polarized doughnut beams as a tool for tuning the field distribution in the focus of a high numerical aperture （NA） lens. Different and relevant states of polarization as well as field distributions can be created by the simple turning of a λ/2 retardation wave plate placed in the excitation path of a micro- scope. The realization of such a versatile excitation source can provide an essential tool for nanotechnology investigations and biomedical experiments.