The images of the silicon test object has been carried out. An image for in-line hard X-ray hologram is presented. The transmission of a hologram image for hard X-ray radiation using Fresnel phase zone plate has been investigated.
We propose that viewing angle expansion of the holographic image can be realized by using high-order diffraction beams caused by the pixel structure sampling the hologram data. The diffractive beam propagating to new optical axis direction plays a role in a modulated carrier similar to a carrier signal of the off-axis holography, which makes new viewing zone of the reconstruction image. The reconstructed image in the Fresnel hologram is deformed along new viewing direction, whereas the Fourier hologram enables to retrieve three-dimensional image with other perspective. High resolution hologram…
We present a three-Charge-Coupled-Device (three-CCD) camera constructed upon multiplexed volume holographic gratings. Three incoherent gratings are written on the same holographic plate to guide the incident light into the three monochromatic channels, where images of red, green and blue light are recorded separately by CCD cameras. The reconstructed chromatic image from the monochromatic images shows superior qualities over the images taken by a single CCD camera.
The enhanced-NA Fresnel hologram reconstructs a holographic image at a viewing angle larger than the diffraction angle of a hologram pixel. The image space is limited by the bandwidth of a digital hologram. In this study, we investigate the property of image formation in the extended image space beyond a diffraction zone. A numerical simulation using the phase Fresnel hologram is carried out to observe an extension of image space and the effect of this on the changes in the angular field of view. The phase Fresnel hologram, synthesized by restricting the angular view range to a diffraction ang…
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
The new type of multilevel Fresnel zone plate, consisting of stacked layers with bi-level zone profile has been investigated. The conditions of layers acting as single multilevel Fresnel zone plate have been discussed by numerical simulation. The criteria for layers alignment have been presented. Considered approach of zone plate fabrication allows achieving high level focusing efficiency from one side and decreasing zone profile etching deep from the other.
In this paper, we present the design, fabrication and optical characterization of computer-generated holograms (CGH) encoding information for light beams carrying orbital angular momentum (OAM). Through the use of a numerical code, based on an iterative Fourier transform algorithm, a phase-only diffractive optical element (PH-DOE) specifically designed for OAM illumination has been computed, fabricated and tested. In order to shape the incident beam into a helicoidal phase profile and generate light carrying phase singularities, a method based on transmission through high-order spiral phase pl…
We present a reconstruction technique for simultaneous retrieval of absorption and phase shifting properties of an object recorded by in-line holography. The routine is experimentally tested by applying it to optical holograms of a pure phase respectively amplitude object of micrometer dimensions that has been machined into a glass-plate using a focused ion beam. The method has also been applied to previously published electron holograms of single DNA molecules.
Fresnel zone plates are diffractive elements that are essential to form images in many scientific and technological areas, especially where refractive optics is not available. One of the main shortcomings of Fresnel zone plates, which limit their utility with broadband sources, is their high chromatic aberration. Recently presented, Fractal Zone Plates (FZPs) are diffractive lenses characterized by an extended focal depth with a fractal structure. This behaviour predicts an improved performance of FZPs as image forming devices with an extended depth of field and a reduced chromatic aberration.…
Strict requirements were imposed on the sizes of testing sample in the previously suggested scheme of hard X-ray Fourier-transform holography based on a two-block Fresnel zone plate interferometer with common optical axis. The failure of these requirements leads to appearance of noise in the reconstructed image. In this work, the mechanism of noise formation, as well as possibility of its suppression are considered.
The construction of fractal generalized zone plates (FraGZPs) from a set of periodic diffractive optical elements with circular symmetry is proposed. This allows us to increase the number of foci of a conventional fractal zone plate (FraZP), keeping the self-similarity property within the axial irradiance. The focusing properties of these fractal diffractive optical elements for points not only along but also in the close vicinity of the optical axis are investigated. In both cases analytical expressions for the irradiance are derived. Numerical simulations of the energetic efficiency of FraGZ…
Extraordinary optical transmission and good focusing properties of a two-dimensional scattering structure is presented. The structure is made of Fresnel zone plates periodically arranged along two orthogonal directions. Each plate consists of two ring-shaped waveguides supporting modes that match the symmetry of a circularly polarized incident plane wave. High field concentration at the focal plane is obtained with short transverse and long longitudinal foci diameters. Optical vortex excitation in a paraxial region of the transmitted field is also observed and analysed in terms of cross-polari…
Ultrathin optical limiters are needed to protect light sensitive components in miniaturized optical systems. However, it has proven challenging to achieve a sufficiently low optical limiting threshold. In this work, we theoretically show that an ultrathin optical limiter with low threshold intensity can be realized using a nonlinear zone plate. The zone plate is embedded with nonlinear saturable absorbing materials that allow the device to focus low intensity light, while high intensity light is transmitted as a plane wave without a focal spot. Based on this proposed mechanism, we use the fini…
Fresnel incoherent correlation holography (FINCH) is a self-interference based super-resolution three-dimensional imaging technique. FINCH in inline configuration requires an active phase modulator and at least three camera shots to reconstruct objects without the twin image and bias terms. In this study, FINCH is realized using a randomly multiplexed bifocal binary Fresnel zone lenses fabricated using electron beam lithography. A modified hologram reconstruction mechanism is presented which introduces the single shot capability in FINCH. A point spread hologram library was recorded using a po…
We created a novel optical security device that integrates multiple computer-generated holograms within a single colour image. Under white light, this "holographic colour print" appears as a colour image, whereas illumination with a red, green, or blue beam from a handheld laser pointer projects up to three different holograms onto a distant screen. In our design, all dielectric layered pixels comprising phase plates (phase control) and structural colour filters (amplitude control) are tiled to form a monolithic print, wherein pixel-level control over the phase and amplitude of light allows us…
Fresnel lens has a long history in optics. This concept at non-optical wavelengths is also applicable. In this paper we report design and fabrication of a half and quarter wave dielectric Fresnel lens made of Plexiglas, and a Fresnel reflector at 11.1 GHz frequency. We made two lenses and one reflector at same frequency and compare their gain and radiation pattern to simulated results. Some methods for better focusing action will be introduced.
Fresnel Zone Plates (FZP) are to date very successful focusing optics for X-rays. Established methods of fabrication are rather complex and based on electron beam lithography (EBL). Here, we show that ion beam lithography (IBL) may advantageously simplify their preparation. A FZP operable from the extreme UV to the limit of the hard X-ray was prepared and tested from 450 eV to 1500 eV. The trapezoidal profile of the FZP favorably activates its 2nd order focus. The FZP with an outermost zone width of 100 nm allows the visualization of features down to 61, 31 and 21 nm in the 1st, 2nd and 3rd or…
We propose a family of zone plates which are produced by the generalized Fibonacci sequences and their axial focusing properties are analyzed in detail. Compared with traditional Fresnel zone plates, the generalized Fibonacci zone plates present two axial foci with equal intensity. Besides, we propose an approach to adjust the axial locations of the two foci by means of different optical path difference, and further give the deterministic ratio of the two focal distances which attributes to their own generalized Fibonacci sequences. The generalized Fibonacci zone plates may allow for new appli…
The standard zone plate assumes that the shortest ray connecting a radiation source and a detection point has a phase of 0 deg thereby defining a reference phase. Here we examine the experimental consequences of varying this reference phase from 0 deg to 360 deg. It is concluded that reference phase is an intrinsic and useful property of zone plates.
To generate hollow chain-like beams the diffraction of the first order Bessel beam by zone plate with two odd open Fresnel zone has been investigated. It has been shown that the capsules size is influenced by the number of the second odd open Fresnel zone and by the zone plate focal length. A hollow chain-like beam has been experimentally generated as a result of the first order Bessel beam diffraction by zone plate with the first and the ninth open Fresnel zones. The orbital angular momentum presence has been proved experimentally. The main features of the beam have been investigated. Suffici…
We present a new family of diffractive lenses whose structure is based on the combination of two concepts: photon sieve and fractal zone plates with variable lacunarity. The focusing properties of different members of this family are examined. It is shown that the sieves provide a smoothing effect on the higher order foci of a conventional lacunar fractal zone plate. However, the characteristic self-similar axial response of the fractal zone plates is always preserved.
Diffractive zone plate optics uses a thin micro-structure pattern to alter the propagation direction of the incoming light wave. It has found important applications in extreme-wavelength imaging where conventional refractive lenses do not exist. The resolution limit of zone plate optics is determined by the smallest width of the outermost zone. In order to improve the achievable resolution, significant efforts have been devoted to the fabrication of very small zone width with ultrahigh placement accuracy. Here, we report the use of a diffractometer setup for bypassing the resolution limit of z…
We presents the results of study of focusing and imaging properties of double-lens system for hard x-ray radiation consisting of two Fresnel zone plates (ZP) made from silicon. We demonstrate for the first time the phenomenon of focusing by two crystal ZP located at significant distance from each other. We investigate by both theoretically and experimentally the peculiarities of intensity distribution at the focal plane during a scan by second ZP normally to the optical axis of the system. We investigate as well the intensity distribution along the optical axis for our double-lens system from …
We optically assess Fresnel zone plates (FZPs) that are designed to guide cold atoms. Imaging of various ring patterns produced by the FZPs gives an average RMS error in the brightest part of the ring of 3% with respect to trap depth. This residue will be due to the imaging system, incident beam shape and FZP manufacturing tolerances. Axial propagation of the potentials is presented experimentally and through numerical simulations, illustrating prospects for atom guiding without requiring light sheets.
A brief, tutorial account is given of the differences between the near and far regions of the elec-tromagnetic field emphasizing the source-dependent behavior of the former and the universal properties of the latter. Field patterns of near-field plates, that is, metasurfaces used for sub-wavelength applications, are discussed in some detail. Examples are given of fields that decay away from the plates in an exponential manner, a ubiquitous feature of many interface problems, and metasurfaces for which the decay is not exponential, but algebraic. It is also shown that a properly designed system…
A transverse computer-generated hologram (CGH) diffracts and provides flexible control of incident light by steering it to any point in the projected image plane - i.e. CGHs are able to direct the light to where it is needed and away from where it is not. In addition, the number of resolvable points in the image projection plane is a function of the CGH's pixel count. Here we report a longitudinal CGH (LCGH), a photonic structure, which swaps the ability to steer light toward fixed spatial points for digital control in the frequency domain. This is of particular interest in the context of tuna…
We have extended Laser Doppler holographic microscopy to transmission geometry. The technique is validated with living fish embryos imaged by a modified upright bio-microcope. By varying the frequency of the holographic reference beam, and the combination of frames used to calculate the hologram, multimodal imaging has been performed. Doppler images of the blood vessels for different Doppler shifts, images where the flow direction is coded in RGB colors or movies showing blood cells individual motion have been obtained as well. The ability to select the Fourier space zone that is used to calcu…
Fibonacci or bifocal terahertz (THz) imaging is demonstrated experimentally employing silicon diffractive zone plate (SDZP) in a continuous wave mode. Images simultaneously recorded in two different planes are exhibited at 0.6 THz frequency with the spatial resolution of wavelength. Multi-focus imaging operation of the Fibonacci lens is compared with a performance of the conventional silicon phase zone plate. Spatial profiles and focal depth features are discussed varying the frequency from 0.3 THz to 0.6 THz. Good agreement between experimental results and simulation data is revealed.
In the visible spectrum vortex beams have found various applications, ranging from optical tweezers to super-resolution imaging. Recently, these beams have been demonstrated using X-rays and electron beams. However, so far, no in-depth discussion has been carried out on the vortex quality, which could become essential for a variety of vortex applications. Here, we investigate the mode conversion efficiency (MCE), vortex structure and stability (in terms of vortex splitting) of the vortex fields generated by spiral zone plates (SZP). We have designed and fabricated SZPs with varying topological…
We propose and demonstrate a single channel interferometer that can be used to study how vortex beams propagate. The interferometer consists of a multifunctional diffractive optical element (MDOE) synthesized by the spatial random multiplexing of a Fresnel zone plate and a spiral Fresnel zone plate with different focal lengths. The MDOE generates two co-propagating beams, such that only the beam carrying orbital angular momentum is modulated by an annular stack of thin scatterers located at the focal plane of the Fresnel zone plate, while the other beam passes through the centre of the annulus…
Scalability in Simulating a Large-Aperture, Fresnel Zone Plate Lens for a Conceptual Space Telescope
Korea Advanced Institute of Science and Technology (KAIST)(韩国科学技术院);Institute of Materials Research and Engineering (IMRE), Agency for Science and Technology and Research (A*STAR)(材料研究与工程研究所,科学与技术研究局)
Diffractive cascades for polychromatic hard X-ray focusing
Research Laboratory of Electronics, MIT(麻省理工学院电子学研究实验室);Department of Electrical Engineering and Computer Science, MIT(麻省理工学院电气与计算机工程系);Department of Mechanical Engineering, MIT(麻省理工学院机械工程系);Edward L. Ginzton Laboratory, Stanford(斯坦福大学爱德华·L·金斯顿实验室)