Fresnel phase plate

Fig. 2.19 Various types of DOE lenses, a Fresnel zone plate b Fresnel phase plate c Fresnel phase plate with soft edges d binary multilevel phase FZP e blazed Fresnel lens f Fresnel lens (continual kinoform lens, equivalent to a binary DOE lens with an infinite number of levels)...

In reality, the Fresnel phase plates are often with gradually changing edges, Fig. 2.19c. 

The diffraction efficiency of a multilevel Fresnel phase plate (the ratio between the incident and the transmitted optical power pj is calculated as [136]... 

Fig. 2 Laser written micro-optical components, a Optical microscopic image of a Y coupler drawn in pure fused silica, which guides 514.5-nm light from an argon-ion laser. The scattered radiation from the coupled argon-ion light is observed in the photograph. The vertical direction is magnified with respect to the horizontal direction for clarity, b Phase contrast microscopic image of one of the two X-couplers that make up a Mach-Zehnder interferometer, c Optical microscopic image of a Fresnel zone plate...

Figure 5. Schematic arrangement for hologram formation with an electron biprism. A plane wave illuminates the specimen placed off-axis. After the object lens a wire is placed between two earthed plates. The wire is the electron optical analog of a Fresnel biprism and causes the unperturbed and perturbed waves forming the electron hologram to interfere. The object phase-shift causes a displacement in the hologram fringes, and is thus observable.

Ren et al. reported the fabrication of a Fresnel lens using a photomask with zone plate patterns [9]. The LC monomer in the zones cured with more UV intensity would lead to smaller LC droplets. Conversely, the zones with weaker UV exposure would result in larger nanoscale droplets. When a uniform voltage was applied to the zone plate, the refractive index (or phase) of the... 

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