Phase masks

In this paper, we introduce a new method for image enhancement of optical systems with radially symmetric phase masks. The optical system with a traditional radial symmetric phase mask would result in a dot point spread function.

8p videadpool 05-05-2023 9 4   Download

The paper has proposed a method for correcting the effect of temperature on the imaging quality of thermal imaging systems by wavefront coding technology. A cubic phase mask was added to the aperture diaphragm of the thermal imaging objective to obtain a temperatureinvariant point spread function (PSF).

11p viwmotors 02-12-2022 17 4   Download

The paper adapted Palley’s (2017) notion of policy lock-in and lock-out via hysteresis to propose an entrenchment spiral as a potential mechanism leading to the current degree of coal and fossil fuel extraction entrenchment in Colombia. The paper concludes that the phase-in of LSCE and FE was facilitated by the combination of masking and securitization strategies used by an incumbency regime closely associated with state capture.

25p huangminghao_1902 27-02-2022 11 2   Download

In this paper, we proposed a simple rational phase mask with two mask parameters to extend the depth of field. A series of performance comparison between the proposed phase mask with the cubic, logarithmic, sinusoidal, and exponential phase mask is presented.

9p viirene2711 01-10-2020 13 2   Download

The surface profile of Fresnel lens during the fabrication process depends on many factors including the thickness, flatness, and pattern clarity of a photoresist (PR) film used as a hard mask for the Si lithography. SU-8 PR with a high viscosity, which is capable of creating large thickness films, can be used as a hard mask in the Fresnel lens fabrication processes. However, it is not easy to achieve a film thickness of about 10 µm with the requirement of a flat surface, free of air bubbles after the baking phases.

5p caygaocaolon6 22-07-2020 46 2   Download

In this paper, an advanced logarithmic phase mask is proposed and its performance is investigated. The essential performance characteristics of phase masks are shown, including the defocused modulation transfer functions (MTF), integral area of the MTF, Hilbert space angle, non-axial Strehl ratio, and decoded images. The results have demonstrated that our phase mask is highly beneficial to extend the depth of field of hybrid optical systems. The advantages of the proposed phase mask in comparison to some other masks are also pointed out.

9p thuyliebe 08-10-2018 27 0   Download