Gabor Zone Plate Research Articles

Optical vortices: A methodology for generating single-focus phase singularity with binary square spiral zone plates

<p indent="0mm">Since 1992, the British researcher Allen demonstrated theoretically and experimentally that vortex beams have orbital angular momentum, many novel optical physical phenomena have been discovered through the study of optical vortices, and they have a wide application prospect in optical manipulation, optical communication, photonic chip and other fields. By combining the advantages of square spiral zone plate and Gabor zone plate, a novel binary single focused square spiral zone plate is designed to realize the optical vortex with square symmetry and alleviate the influence of the higher order foci in the propagation direction. The theoretical results are consistent with the experimental results. This finding has potential in the applications of multi-particle manipulation and 3D imaging.

Three-wave radial shearing interferometer.

We propose a simple and compact three-wave radial shearing interferometer (TWRSI). This interferometer is constructed by a Gabor zone plate (GZP) and a charge-coupled device (CCD). The nominal plane wavefront under test is diffracted by the GZP into three orders (i.e., a parallel beam, a converging spherical beam, and a diverging spherical beam) leading to an interference pattern. In the imaging plane, three beams can be considered as being the copies of the incident beam, the compressed beam, and the expanded beam, respectively. A CCD detector located in the vicinity of the GZP records this interference pattern. Wavefront can be reconstructed by a single interferogram. The experiment result shows that the proposed method is correct and accurate. This TWRSI is compact, vibration insensitive, suitable for measurement of continuous and transient wavefront.

Toward binary Gabor zone plate by modulating zones width

In this paper, a novel concept of modulated width zone plate (MWZP) is proposed to realize a binary Gabor zone plate (GZP) with single focus. By modulating the zones width as sinusoidal random distribution, higher-order foci can be effectively suppressed. The physical design is verified with numerical simulation and demonstration experiments in visible light region. The performance of the modulated width zone plate is determined by the number of zones used. It works well only when enough zones are utilized. The zone plate is easy to be fabricated employing nanofabrication technology, since it is composed of complete zones, similar to Fresnel zone plates (FZP). This work offers new opportunities for x-ray spectroscopy and microscopy in physics research.

Multiple beam steering using dynamic zone plates on a micromirror array

Three dimensional laser beam steering has been demonstrated using a single optical device -a DMD micro-mirror array. Laser beam focus position is controlled using dynamically adjustable zone plates. These zone plates take the form of elliptical Fresnel zone plates or other variations such as binary Gabor zone plates. Active beam control can be realised without the need for a pair of galvanometer mirrors and a focusing lens. Writing multiple zone plate patterns to the DMD enables multiple focussed spots to be generated and controlled independently

Investigation of focusing and correcting aberrations with binary amplitude and polarization modulation.

We investigate the focusing and correcting wavefront aberration of an optical wave using binary amplitude and polarization modulation. Focusing is performed by selectively modulating the field in different zones of the pupil to obtain on-axis constructive interference at a given distance. The conventional Soret zone plate (binary amplitude profile) is expanded to a polarization Soret zone plate with twice the focusing efficiency. Binary pixelated devices that approximate the sinusoidal transmission profile of a Gabor zone plate by spatial dithering are also investigated with amplitude and polarization modulation. Wavefront aberrations are corrected by modulation of the field in the pupil plane to prevent destructive interference in the focal plane of an ideal focusing element. Polarization modulation improves the efficiency obtained by amplitude-only modulation, with a gain that depends on the aberration. Experimental results obtained with Cr-on-glass devices for amplitude modulation and liquid crystal devices operating in the Mauguin condition for polarization modulation are in very good agreement with simulations.

Carbon Nanotube Array Based Binary Gabor Zone Plate Lenses

Diffractive zone plates have a wide range of applications from focusing x-ray to extreme UV radiation. The Gabor zone plate, which suppresses the higher-order foci to a pair of conjugate foci, is an attractive alternative to the conventional Fresnel zone plate. In this work, we developed a novel type of Beynon Gabor zone plate based on perfectly absorbing carbon nanotube forest. Lensing performances of 0, 8 and 20 sector Gabor zone plates were experimentally analyzed. Numerical investigations of Beynon Gabor zone plate configurations were in agreement with the experimental results. A high-contrast focal spot having 487 times higher intensity than the average background was obtained.

Zone Plates for X-Ray Focusing (Review)

Various zone plates: amplitude, amplitude-phase, and phase ones (including Fresnel and Gabor zone plates, Laue- and Bragg-Fresnel lenses, photon sieves, and aperiodic zone plates), as well as their properties and X-ray focusing possibilities, are described and analyzed.

High-resolution reconstruction of Fresnel zone plate coded imaging

Zone plate coded imaging is an experimental technique for particle and strong X-ray imaging, which is widely applied to astronomy, nuclear medicine, and laser inertial confinement fusion researches. From conventional perspective, spatial resolution of zone plate depends on the encoding zone plate width of outermost ring r with a size greater than 1.22r. In X-ray region, however, the outermost ring width of Fresnel zone plate is limited by processing technology. Such a limitation makes it impossible to fabricate a sufficiently small zone plate, thus restricting the applications of Fresnel zone plate coded imaging. In this paper, we present a new reconstruction method of zone plate coded imaging by using a higher-order order Gabor zone plate. With the proposed method, higher spatial resolution can be achieved than with the regular methods, thus the spatial resolution is improved by 1/m times the width of outermost ring (where m is a positive integer). Consequently such a breakthrough goes beyond the limits of Rayleigh criterion in general.

Fabrication of self-standing binary Gabor zone plate and its single order diffraction

The Gabor zone plate is an ideal zone plate with single focus spot, which has the potential applications in spectroscopy, X-ray imaging, etc. However, the Gabor zone plate is very difficult to prepare because of its sinusoidal transmission characteristic, thereby restricting its applications. Traditionally, the zone plate is prepared on the transparent substrate such as quartz glass, polyimide, etc. This restricts the applications of Gabor zone plates in the extreme ultraviolet and soft X-ray frequency band due to the strong absorption of quartz and polyimide in such bands.In this work, we report a method of preparing the self-standing binary Gabor zone plate by using the focused ion beam direct writing. By combining the techniques of focused ion beam and chemical wet etching, the binary Gabor zone plate with self-standing and curved structure is fabricated. The main characteristic parameters of the Gabor zone plate are as follows: the diameter of 1400 m, the radius of the first zone 90 m, the outset zone number of 60, and a gold absorber thickness of 500 nm. The focusing properties of the self-standing binary Gabor zone plate are measured at different transfer distances with a 355 nm laser. The experimental results show that the high-order focus is removed with only the first-order focus spot reserved, and the focal distance is 2.28 cm, which is in agreement with the theoretical value of 2.41 cm. The self-standing Gabor zone plate is free from the influence of the substrate. Therefore, this kind of binary Gabor zone plate has potential applications in ultraviolet and soft X-ray regions.

Focusing single-order diffraction transmission grating with a focusing plane perpendicular to the grating surface.

By combining the single-order dispersion properties of quasi-sinusoidal single-order diffraction transmission gratings (QSTG) and the single-foci focusing properties of annulus-sector-shaped-element binary Gabor zone plate (ASZP), we propose a novel focusing single-order diffraction transmission grating (FSDTG). Different from the diffraction patterns of a normal transmission grating (TG), it has a focusing plane perpendicular to the grating surface. Numerical simulations are carried out to verify its diffraction patterns in the framework of Fresnel-Kirchhoff diffraction. Higher-order diffraction components of higher harmonics can be effectively suppressed by the FSDTG we designed. And we find that the focal depth and resolving power are only determined by the structure parameters of our FSDTG by theoretical estimations.

Single-focus x-ray zone plate by stagger arrangement of zones

In this paper a novel single-focus x-ray zone plate is proposed by stagger arrangement of zones, which would be technically easier to manufacture. Theoretical design shows that the transmission function of the plate is a cosine function of radius, like that of a Gabor zone plate. Numerical simulation at the wavelength of 0.275 nm shows that the plate is of single-order focusing, with spatial resolution limit the same as that of the corresponding conventional zone plate, and the first-order diffraction efficiency of 11.5%. The plate can also work for single-order focusing at other x-ray wavelengths.

Realizing a Gabor zone plate with quasi-random distributed hexagon dots

We propose a quasi-random-dot-array binary Gabor zone plate (QBGZP) with focusing properties of single order foci only. These features are verified with simulations and experiments in the visible light region. Moreover, we find that the performance of QBGZP, which is composed of hexagon patterns, is determined by the ratio of hexagon circumcircle diameter to the outermost zone width. The QBGZP offers a potential alternative for focusing and imaging in the soft x-ray and extreme ultraviolet region.

Annulus-sector-element coded Gabor zone plate at the x-ray wavelength

It is proposed in this paper that an x-ray Gabor zone plate can be realized by properly arranging annulus-sector-shaped nanometer structure apertures along each zone. This provides a new coding methodology which can be used to fabricate a binary zone plate with single order foci only. Numerical simulation results show good agreement with the physical design.

准随机点阵二值化Gabor波带片聚焦特性的数值计算

Fresnel zone plate has a dominating focus and a series of high-order foci, it will be influenced by advanced diffraction when used as an imaging device. A Gabor zone plate has only one focus, it has much better diffraction properties. However, it is hard to fabricate. The emergence of quasi-random-dot-array binary Gabor zone plates can solve this problem. In this paper, design of quasi-random-dot-array binary Gabor zone plates is introduced, and diffraction properties of Fresnel zone plate and binary Gabor zone plate are simulated by optimized program. Analyzing and comparing the simulation show that the quasi-random-dot-array binary Gabor zone plate could restrain advanced diffraction．

Improved Zone Plate Coded Imaging Technique by Using FourSpecial Designed Gabor Zone Plates

Direct-current component, high-order artifacts, and side lobe distortionprovide serious drawbacks in the application of Fresnel zone plate codedimaging (ZPCI). The presentation provided here proposes a novel way toresolve all the above-mentioned problems. Four different Gabor zoneplates are suggested to substitute the one Fresnel zone plate used inthe conventional ZPCI. Perfect reconstruction will be obtained whenintegrally analysing the four coded images. Primary numerical simulationprovided here shows good result.

Modified binary Gabor zone plates

We have proposed a novel principle for design of the binary Gabor zone plate (GZP) that can produce the desired focal-plane curves. The modified GZP can be fabricated as easily as the Fresnel zone plate (FZP). The proposed GZP has great flexibility in terms of manipulating the focusing properties. Optical experiments have confirmed the reliability of the GZP in focusing light into the specified area. The investigation on the factors affecting the performance of the GZP is presented. The low cost and easy production of the element show that it can serve an alternative to refractive lens in the short wavelength region where refractive optics is not applicable owing to possible strong absorption.

Computational study of diffraction patterns for near-field Fresnel and Gabor zone plates.

Near-field designs of Fresnel and Gabor zone plates are computationally analyzed by using versions that allow the foci to be brought closer to the plate than in the usual far-field applications. It is found that the Fresnel plate has a dominant primary conjugate pair of foci well inside the far-field region and a more intense primary focus and smaller off-focal-plane sidelobes than the near-field Gabor systems, thus yielding a superior imaging performance.

High-efficiency cosine-approximated binary Gabor zone plate

A cosine-approximated binary Gabor zone plate is proposed. The zone plate is fabricated by standard photographic techniques. It was evaluated by simulation and by experiment to match the focusing behavior of an ideal Gabor zone plate, but it has a focusing efficiency at least 23% higher than that of a binary Gabor zone plate. Duplication of an alphabetic character to form a 4 × 4 array of images with little astigmatism by the proposed zone-plate array is demonstrated.

A switchable liquid crystal binary Gabor lens

Nematic liquid crystal is used in a transparent patterned electrode cell to implement an electrically switchable Gabor lens. The binary Gabor zone plate used produces only a single pair of conjugate foci, unlike the multiple foci associated with Fresnel zone plates. Fabrication of a device is detailed and its focusing ability demonstrated.

Gabor zone plate with binary transmittance values

A methodology is presented for producing a Gabor zone plate by using a binary transmittance function that is both radially and azimuthally distributed on the surface of the plate. The measured optical properties of such a plate are shown to be in agreement with those of the idealized Gabor plate that possesses a radially sinusoidal transmittance function.