Speckle reduction using phase plate array and lens array

In this paper,a solution for speckle reduction using phase plate array(PPA)and lens array(LA)in a motionless way is proposed.The specially designed PPA is composed of sub-phase plates,which are constituted by phase patterns formed by Hadamard sub-matrices.Each component of the proposed optical system should satisfy the stated relationships.The incident laser beam will be incoherent after passing through PPA,and superpose on the screen under the action of LA and main lens.Speckle reduction can be achieved by the averaging of the incoherent speckle patterns.Because of abandoning the mechanical movement,it will be suitable for laser displays and images.

Design of 2D-Bootlace Lens with Five Focal Feed for Multiple Beam Forming

Utility of microwave bootlace lens is well established. For broadband and wide scanning network, it is required to op-timize and use features of this lens for better communication and scanning device. This report presents the design of a compact 2D bootlace lens with five focal feed for multiple beam forming. This design will help in reducing phase error and will provide power efficiency and better resolution during target tracking. This design will provide better aperture efficiency and scanning angle.

Liquid crystal Fresnel lens display

A novel see-through display with a liquid crystal lens array was proposed.A liquid crystal Fresnel lens display（LCFLD） with a holographic screen was demonstrated.The proposed display system has high efficiency,simple fabrication,and low manufacturing cost due to the absence of a polarizer and color filter.

A multi-photon(7×7)-focus 3D laser printer based on a 3D-printed diffractive optical element and a 3D-printed multi-lens array

One of the challenges in the field of multi-photon 3D laser printing lies in further increasing the print speed in terms of voxels/s.Here,we present a setup based on a 7×7 focus array(rather than 3×3 in our previous work)and using a focus velocity of about 1 m/s(rather than 0.5 m/s in our previous work)at the diffraction limit(40×/NA1.4 microscope objective lens).Combined,this advance leads to a ten times increased print speed of about 108 voxels/s.We demonstrate polymer printing of a chiral metamaterial containing more than 1.7×10^(12) voxels as well as millions of printed microparticles for potential pharmaceutical applications.The critical high-quality micro-optical components of the setup,namely a diffractive optical element generating the 7×7 beamlets and a 7×7 lens array,are manufactured by using a commercial two-photon grayscale 3D laser printer.

A compact and high-power silicon-wafer solar strip-cells-array module integrated with an array concentrator

A compact, low-cost and high-output-power silicon-wafer solar strip-cells-array module （SCAM） wus experimentally demonstrated. The proposed SCAM consisted mainly of a silicon-wafer strip-cell sparse array and low-concentration- ratio array concentrator based on an epoxy resin polymer （ERP） cylindrical piano-convex lens. A polymer replication process based on a polydimethylsiloxane mold was used to fabricate the ERP lens array concentrator. The results show that 46.94% of the silicon-wafer cell was saved in the designed SCAM. Moreover, the output power of the SCAM with a low concentration ratio of 8 suns was improved by 8.6%, compared with a whole piece of a conventional silicon-wafer solar cell with the same area as the module. The proposed method encapsulating solar cells provides a means to reduce the usage of silicon cells in modules as well as improving the output power of modules.

Cross-lenticular lens array for full parallax 3-D display with crosstalk reduction

As a 3-D display technology,stereoscopic imaging with lenticular lens sheet can only offer viewers the horizontal parallax.To reconstruct the 3-D image with parallax in both horizontal and vertical directions,the full parallax technique with micro-lens array was proposed.But due to the fabrication constraints and cost concerns of the micro-lens array,application of the full parallax technique is restricted in practice.In this paper we revisited the lenticular sheet method and cross-lenticular lens array formed by two lenticular sheets overlapped orthogonally.By analyzing the optical properties of this cross-lenticular lens array,we found that it has reasonable imaging qualities as a conventional micro-lens array.Besides,due to the poor optical property of the outskirt area of the cross-lenticular lens,the cross-lenticular lens array has better crosstalk suppression capability than the conventional one.Based on the analysis,in this paper,we used the proposed lens array to reconstruct a 3-D image and verified its practicability.The cross-lenticular lens array was found feasible to take the full parallax technique into commercial applications,with comparable advantages in terms of low-cost and easy fabrication over a large area.

The Computer Analysis of the Excimer Laser Beam Intensity Uniformization by Rotational Lens Array

The excimer laser has important applications in many fields. Because of its non-uniform intensity distribution there are some limits in applications. This paper introduces rotational lens array to improve intensity distributions. The intensity variation is reduced to 1 percent by computer simulation.

Electrical Responses and Stable Behavior of Polyaniline-polyurethane Concave Lens Array Film in Electrolyte

We present a synthetic methodology of polyaniline-polyurethane（PANI-PU） copolymer using interfacial in situ polymerization. PANI-PU copolymer was obtained through in situ polymerization of aniline precursor and the concave lens array film was molded by water drops. The fabrication of unique structured film was obtained through a solvent evaporation self-formed system. The detailed nanostructures of the film were illustrated by scanning electron microscopy（SEM） images, which showed homogeneous structure in a close-packed hexagonal arrangement. The di- mension of well-structured hexagon ranged from 10.8 ~tm to 12.9 lxm. Sensitive electrical responses of the concave lens array film resulted in the changes of swelling/shrinkage ratio in electrolyte under various conditions. Dimen- sional control of the film was achieved via adjusting a series of parameters including time, voltage, concentration and type of electrolyte. The electrical responses resulted rearranged molecular chain caused by redox reaction via powered PANI. Most importantly, the film maintained its response characteristics after 16 cycles. The high stability of film could be directly attributed to PU doping, which could help the PANI enhancing the mechanical strength and chemical solubility in solution.

A novel fabrication technique for three-dimensional concave nanolens arrays

A novel facile technique is proposed for fabricating three-dimensional(3D)concave nanolens arrays on a silicon substrate.The technique leverages an inherent characteristic of the polymethyl methacrylate(PMMA)resist during inductively coupled plasma(ICP)etching.The tendency for plasma ions to accumulate at the edge of the PMMA resist helps create a local electric field that causes the ions to etch the sidewall of the PMMA resist.This process progressively increases the uncovered area,resulting in a graded etched depth or a concave structure in the substrate.In addition,using a given ICP etching recipe,the time required for a PMMA resist to be removed by sidewall etching is determined by its width.The use of PMMA resist of different widths enables one to achieve structures of varying etched depths and thus a 3D lens array.Optical characteristics of the fabricated nanolens were simulated using the FDTD(Finite-difference time-domain)method,and focal lengths ranging from 150 nm to 420 nm were obtained.This type of nanolens is very useful in ultraviolet optical devices and CMOS image sensors.

Rapid fabrication of mini droplet lens array with tunable focal length

A rapid and cost-effective method for fabricating mini lens arrays is proposed. The lenses are made of silicone oil droplets and filled inside a polydimethylsiloxane(PDMS) elastomer. The lens arrays of different initial focal lengths and apertures can be fabricated by using the droplets of different volumes. Due to good elastic behavior of PDMS, the droplet lenses can be flexibly deformed, and the focal length and numerical aperture can be tuned by applying an external force on the PDMS elastomer. Furthermore, an apparatus for focal length tuning is designed and employed in the imaging system.

Theoretical analysis of lens array for uniform irradiation on target in multimode fiber lasers

We propose and demonstrate a scheme to smooth and shape the on-target patterns in multimode fiber lasers, which includes expanding-collimating system and lens array （LA）. A smooth pattern with flat-top and sharp-edge profiles can be obtained with the irradiation nonuniformity decreasing significantly. We analyze the effects of the parameters such as defocus distance, the tilt angles, the number of the incident fiber lasers, and the diffraction-weakened LA on the uniformity irradiation of target by numerical simulations.

Integral imaging-based tabletop light field 3D display with large viewing angle

Light field 3D display technology is considered a revolutionary technology to address the critical visual fatigue issues in the existing 3D displays.Tabletop light field 3D display provides a brand-new display form that satisfies multi-user shared viewing and collaborative works,and it is poised to become a potential alternative to the traditional wall and portable display forms.However,a large radial viewing angle and correct radial perspective and parallax are still out of reach for most current tabletop light field 3D displays due to the limited amount of spatial information.To address the viewing angle and perspective issues,a novel integral imaging-based tabletop light field 3D display with a simple flat-panel structure is proposed and developed by applying a compound lens array,two spliced 8K liquid crystal display panels,and a light shaping diffuser screen.The compound lens array is designed to be composed of multiple three-piece compound lens units by employing a reverse design scheme,which greatly extends the radial viewing angle in the case of a limited amount of spatial information and balances other important 3D display parameters.The proposed display has a radial viewing angle of 68.7°in a large display size of 43.5 inches,which is larger than the conventional tabletop light field 3D displays.The radial perspective and parallax are correct,and high-resolution 3D images can be reproduced in large radial viewing positions.We envision that this proposed display opens up possibility for redefining the display forms of consumer electronics.

Achromatic on-chip focusing of graphene plasmons for spatial inversions of broadband digital optical signals

On-chip focusing of plasmons in graded-index lenses is important for imaging,lithography,signal processing,and optical interconnects at the deep subwavelength nanoscale.However,owing to the inherent strong wavelength dispersion of plasmonic materials,the on-chip focusing of plasmons suffers from severe chromatic aberrations.With the well-established planar dielectric grating,a graded-index waveguide array lens(GIWAL)is proposed to support the excitation and propagation of acoustic graphene plasmon polaritons(AGPPs)and to achieve the achromatic on-chip focusing of the AGPPs with a focus as small as about 2%of the operating wavelength in the frequency band from 10 to 20 THz,benefiting from the wavelength-independent index profile of the GIWAL.An analytical theory is provided to understand the on-chip focusing of the AGPPs and other beam evolution behaviors,such as self-focusing,self-collimation,and pendulum effects of Gaussian beams as well as spatial inversions of digital optical signals.Furthermore,the possibility of the GIWAL to invert spatially broadband digital optical signals is demonstrated,indicating the potential value of the GIWAL in broadband digital communication and signal processing.

Development of an upgraded motional Stark effect diagnostic system on EAST tokamak

A new multi-channel motional Stark effect(MSE)diagnostic system has been developed on the upgraded EAST tokamak,which was installed on the port C to observe a tangential neutral beam.A telecentric imaging lens was deployed to ensure uniform illumination from the core to the boundary.A square fiber head which contained 23 fiber bundles was mounted to this imaging lens;each fiber bundle contained 19 fibers and two of them were assigned to CXRS and BES spectrometer,respectively.The angle tuning method was used for matching the Doppler shift of theσcomponent’s wavelength which was caused by the beam voltage.At the present stage,the MSE system only contains ten channels that would be extended to 23 channels in the future,covering a measurement range from R=1.8 to R=2.27 m with a temporal resolution of 10 ms and a spatial resolution of3 cm.The polarization angle-constrained q profiles and current density profiles were reconstructed with EFIT equilibrium reconstructions.In the sawtooth discharges,the q=1 surface position was validated by the ECE signals,which further verified the rationality of the MSE measurement.

Influence of Parameters in the Design of a Faceted Structure for Incoherent Beam Shaping

A reflective faceted structure is proposed to reshaping an incoherent light beam into two focalized spots-To obtain the desired irradiance distribution on a detector,custom optimization function is written,and the two dimensional tilt angles of each facet are optimized automatically in a pure non-sequential mode in Zemax OpticStudio 16.The result is also confirmed inside LightTools&2 from Synopsys.For measuring the quality of the optimization result in the case of two spots focalization,four factors including efficiency on the detector,uniformity,the root mean square error and the correlation coefficient are calculated.These four factors are used to evaluate the influence of several parameters on the irradiance distribution.These parameters include the incidence angle,the divergence angle,the facet size,the source type and the resolution of the facet angular positions.Finally,an analysis of those parameters is made and the performance of this type of component is demonstrated.

Information Encryption Based on Using Arbitrary Two-Step Phase-Shift Interferometry

A deterministic phase-encoded encryption system is proposed. A lenticular lens array (LLA) sheet with a particular LPI (lenticular per inch) number is chosen as a modulator (key) instead of the random phase molator. The suggested encryption scheme is based on arbitrary two-step phase-shift interferometry (PSI), using an unknown phase step. The encryption and decryption principle is based on an LLA in arbitrary unknown two-step PSI. Right key holograms can be used to theoretically show that the object wavefront is the only one left in the hologram plane and that all accompanying undesired terms are eliminated. The encrypted image can therefore be numerically and successfully decrypted with the right key in the image plane. The number of degrees of freedom of the encryption scheme increases with the distance from the object and the LLA to the CCD, and also with the unknown phase-step and the LLA LPI number. Computer simulations are performed to verify the encryption and decryption principles without a key, with the wrong key and with the right key. Optical experiments are also performed to validate them.

Experiments and analysis of gold disk targets irradiated by smoothing beams of Xingguang Ⅱ facilities with 350 nm wavelength

Gold disk targets were irradiated using focusing and beam smoothing methods on Xingguang (XG-Ⅱ) laser facilities with 350 nm wavelength,0.6 ns pulse width and 20-80 Joules energies. Laser absorption,light scattering and X-ray conversion were experimentally investigated. The experimental results showed that laser ab-sorption and scattered light were about 90% and 10%,respectively,under focusing irradiation,but the laser absorption increased 5%-10% and the scattered light about 1% under the condition of beam smoothing. Compared with the case of fo-cusing irradiation,the laser absorption was effectively improved and the scattered light remarkably dropped under uniform irradiation; then due to the decrease in laser intensity,X-ray conversion increased. This is highly advantageous to the in-ertial confinement fusion. However,X-ray conversion mechanism basically did not change and X-ray conversion efficiency under beam smoothing and focusing irra-diation was basically the same.