We present a new family of pupil masks to control the axial component of the intensity distribution in the focal region of tightly focused light fields. The filters, which consist of a circular clear pupil with a single shaded ring, allow to control the width of the central lobe of the axial spot together with the residual sidelobes energy. The filters can be applied to improve the optical sectioning capacity of different scanning microscopes.

An optical beamformer for antenna arrays based on fiber-optical delay lines for feeding subarrays and spatial light modulators to change the radio-frequency phase of independent antenna elements is proposed. The architecture has the potential to control antenna arrays of a large number of elements. Preliminary experimental results to show the feasibility of the concept are provided.Index Terms-Microwave photonics, optical beamforming, spatial light modulator (SLM).

One of the main challenges in three-dimensional microscopy is to overcome the lack of isotropy of the spatial resolution, which results from the axially-elongated shape of the point spread function. Such anisotropy gives rise to images in which significant axially-oriented structures of the sample are not resolved. In this paper we achieve an important improvement in z resolution in two-photon excitation microscopy through spatial modulation of the incident beam. Specifically, we demonstrate that the design and implementation of a simple shaded ring performs quasi-isotropic threedimensional imaging and that the corresponding loss in luminosity can be easily compensated by most available femtosecond lasers. The outcome looks particularly relevant to nano-fabrication and optical manipulation.

A two-pinhole axially superresolving confocal fluorescence imaging system is presented. Based on the concept of subtractive incoherent imaging, the system described here is equipped with a zero-focus complex-transmittance pupil filter in one of the collector paths. The optical sectioning capacity of the system is 25% superior to that of a free-pupil one-pinhole instrument. q

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