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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．

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.

In laser proton acceleration, the inevitable transverse divergence of proton beam restricts its applications in many fields. In this paper, a structured target with a properly wide channel attached to the backside of a foil is proposed, and the interaction of the ultra-short laser pulse with the structured channel target is investigated via two-dimensional particle-in-cell simulation. The simulations show that for the structured channel target, electrons on the front surface are heated by the incident high-intensity laser pulse and then the induced hot electrons transport through the target to the rear surface, building an electrostatic field in the longitudinal direction to accelerate the protons to high energies as the typical target normal sheath acceleration scheme. In the case of the structured channel target, the simulation results indicate that a strong transverse electrostatic field is created by charge separation along the inner surface of the channel while hot electrons propagate along the channel side walls under the guidance of self-induced magnetic and electric fields, which can focus the emitted proton beam transversely, leading to a smaller divergence. By comparing the channel target case with the traditional foil target case under the same conditions, it is found that the divergence angle of the proton beam from the channel target is reduced significantly. Protons with energies above 3 MeV have a divergence angle of 5.3° at the time of 500 fs in the channel target case, while the value is 17.1° in the foil case for a laser intensity of 5.4×1019 W/cm2. Additionally, the effect of the channel target on the maximum proton energy is considered. The simulation results of the energy spectra reveal that the maximum proton cut-off energy of the channel target is about 1 MeV lower than that of the foil target. This small energy loss is due to the refluxing of the cold electrons on the channel walls, which suppresses the increasing of the sheath potential. Therefore, it is concluded that the focusing electric field can work on the proton beam effectively, leading to a better collimation with conserving the proton energy by using the proposed channel target. Especially when the inner diameter of the channel target is comparable to the laser focal spot size, the proton beam can be confined to a small divergence, and a relatively higher laser energy conversion efficiency can be ensured as well.

A semi-analytical theory of the interaction between a relativistic laser pulse and the overdense plasma to generate an attosecond X-ray source is presented.The physical parameters such as plasma oscillation trajectory,surface electric field and magnetic field can be given by this model,and the high-order harmonic spectrum is also calculated accurately from the solution of the plasma surface oscillations,the obtained result is consistent with the result from the PIC simulation program.This model can be valid for arbitrary laser duration,solid densities,and a large set of laser peak intensities (1018-1021 W/cm2).In addition,the model is not applicable for the small laser focal spots (less than ten times the laser wavelength),although two-dimensional effects such as the pulse finite size may significantly change the movement progress of the electrons,the laser spot can be larger than ten times the laser wavelength under the general laboratory conditions. In this model,the laser energy absorption is small,and the electron kinetic pressure is also small.Due to the radiation pressure of the laser pulse,the electrons are pushed into the solid,forming a very steep density profile.As a result,the relevant forces makes the electrons ponderomotive and the longitudinal electric field is caused by the strong electric charge separation effect.This semi-analytical self-consistent theory can give us a reasonable physical description, and the momentum equation and the continuity equation of the electric and magnetic field at the boundary allow us to determine the plasma surface oscillations.The spatiotemporal characteristics of the reflected magnetic and electric field at the boundary can allow us to determine the emitting characteristics of the high order harmonic. Our results show that the radiation of the attosecond X-ray source is dependent on the plasma surface oscillation. The plasma surface oscillates with a duration about twice the laser optical cycle,and the high-order harmonics also emit twice the laser optical cycle,thus an attosecond pulse train driven by the multi-cycle laser pulse can be formed.By using a few-cycle laser field,the smooth high-order harmonics can be obtained,which leads to a single attosecond pulse with high signal-to-noise ratio.In a word,our calculation results show that the time evolution progress of plasma surface can be controlled by changing the carrier envelope phase of the few-cycle laser pulse,and then the radiation progress of the high-order harmonics can be influenced as result of a single attosecond X-ray pulse.

A new terahertz dispersive device designed for single-shot spectral measurements of broadband terahertz pulses is proposed. With two-dimensional quasi-randomly distributed element design, the device exhibits approximately the dispersive property of single-order diffraction in far field. Its far-field diffraction pattern is experimentally verified employing a continuous terahertz source centered at 2.52 THz and a pyroelectric focal-plane-array camera, which is in good agreement with the numerical result. The device provides a new approach for direct single-shot spectral measurements of broadband terahertz waves.

The primary DD proton spectrum is used for diagnosing the fuel-shell areal density ρR of imploded capsules on Shenguang III (SG-III) prototype laser facility for the first time. A charged particle spectrometer (CPS) with a CR39 nuclear track detector is used to measure the DD proton spectrum. The proton spectrum is determined from both the proton track and its size. A typical proton energy peak shift from 3.02 MeV to 2.6 MeV is observed in our experiment, which yields a maximum ρR larger than 6 mg/cm2.

In single-shot, ultrafast time-resolved measurements, the combination of linear chirp pulse and spectrometer is a common way. In this paper, according to the time-frequency mapping relationship of linear chirp pulse and utilizing an imaging spectrometer as a recording system, we design a chirped pulse velocity interferometer for the ultrafast measurement of free surface velocity. Theoretical research on the principle and applicability shows that picosecond resolution is achievable and the velocity sensitivity is easily adjustable, which greatly widens applications of the velocity interferometer. The numerical simulation of the measurement process shows that reconstructed velocity signal is well consistent with the given velocity, further confirming the feasibility of the chirped pulse velocity interferometer.

Quantum-dot-array diffraction grating(QDADG), with an area of 200 μm×200 μm, a line density of 500 line/mm, an aperture size of 800 nm and a gold absorber of 500 nm thick, is successfully fabricated by focused ion beams. The diffraction properties and relative diffraction efficiencies of QDADG are measured at different transfer distance for 442 nm laser. It is shown that the high-order diffraction is removed from the spectra with only the ±1 and 0 order diffraction lines reserved. Moreover, in accordance with the calculated values obtained using the grating equation, variations of space between the 1st order and the 0th order increase gradually with the increase of transfer distance.

The development trend of single-order diffraction grating is introduced. The feasibility of single-order diffraction grating is theoretically demonstrated, and a novel diffractive optical element named quasi-sinusoidal reflection type single-order diffraction grating(QSRG) is proposed. It can suppress higher order diffraction, and improve the signal-noise-ratio (SNR) and accuracy. The experimental results verify this new type of dispersion component, where the higher order diffraction components are efficiently suppressed, which accords well with theoretical prediction. These results are expected to be widely used in the reflection spectrum measurement system.

The quasi-isentropic compression of material with high strain rate can be obtained by the ramp wave loading of plasma jet produced by laser-driven reservoir target. The quasi-isentropic compression experiments of aluminum are carried out on the high power laser facility of SG-III prototype. The smooth and continuous speed history of free surface of specimen is recorded with a line-imaging velocity interferometer (VISAR). The peak pressure (60 GPa), the rise time of the load (～ 10 ns) and the strain (～ 108 s-1) are derived by the back-integrating method, and the reverberation of compression wave at the rear surface of the sample is observed.

Transmission grating is widely used in measurement of soft X rays. In order to measure the diffraction efficiencies of the transmission grating which is used in laser fusion, the transmission grating was calibrated on Beijing Synchrotron Radiation Facility in the energy region from 200eV to 1600eV, and the experimental results have been obtained. The model for grating efficiency simulation has been developed and calculations using a new so called 7-side quasi-trapezoidal cross section model were carried out. The results from the new model are in good agreement with the experimental data. The exact grating wire cross section is described.

Monoenergetic electron bunches can be generated by the interaction between the ultra-intense laser and underdense plasma on the mm scale. In the experiment conducted on the SILEX-Ⅰ, by the interaction between an ultra-intense femtosecond laser pulse and 2.7 mm supersonic He gas jet, a 58 MeV quasi-monoenergetic electron beam with 15.5% energy spread and 15 mrad beam divergence is produced. The total charge of the electron beam is about 15.4 nC when the laser power is 70 TW. In this paper the experimental conditions, the method and main results are presented.

The performance of micro-focus Fresnel zone plate(MFZP) with the outermost width of 150nm is tested using the Ti spectral line. Experimental data indicates that the image of pinhole with diameter of 125μm fully responses to a pixel of the X-ray CCD camera. Furthermore，the X-ray focal spot is tested with a magnification of 66 by using laser striking the Ti planar target. The MFZP's point spread function is simulated with the integral formula of Fresnel-Kirchhoff diffraction. The simulated results indicate that the MFZP strongly focuses at double foci. The same results are obtained when the object distance and image distance change but keeping the relation of the lens unchanged. The simulation and the experiment indicate that MFZP can be applied to point-to-point imaging of X-ray to realize high spatial resolution imaging for the laser plasmas.

The proton beam accelerated by the interaction of laser with plasma has practical applications in radiography of dense plasma, fast ignition in inertial confinement fusion, and cancer treatment. The application domain is determined by the characteristic of the proton beams, which is affected by a lot parameters. In order to investigate the effect of the initial size of the proton layer, the two-dimensional Particle-In-Cell (2D-PIC) code Flips2D is used. The total energy of proton beam vs. time is studied, and the relation between the duration of acceleration and the period of laser pulse is obtained. The effects of the proton layer initial width and thickness on the divergence angle and the energy spectrum of the proton beam are investigated. The relation between the proton beam characteristics and proton layer initial size is obtained.