A novel method is presented for compensating deflection in temporal-spatial transform pulse shaping system, using single-mode optical fiber instead of a second electrooptic deflector. By changing the width of filtering slit, pulse duration ranging from 740 ps to 4.5 ns is observed, and output beam is of good quality. This novel method has reduced requirements on electrooptic deflector and simplified the whole system.

A LDA pumped highly stable Nd∶YLF ring laser is developed. With an output laser intensity induced negative feedback control of resonator gain, a quasi-continuous prelase with duration of ～100 μs is established, then Q-switch during this prelase. Because the prelase mode is well matched to the resonator eigenmode and with certain intensity, the build up time and intensity of Q-switched pulse are very stable. Experimental results show that intensity instability of output Q-switched pulse doesn′t exceed 4.3%, and time jitter does not exceed ±4 ns.

In this paper, the transmission features of the ultra-short pulsed-laser passing through the serrated aperture and spatial filter is studied in allusion to clean and uniform intensity distribution in the high-energy ultrashort pulse-laser system. The diffraction modulation of ultrashort pulsed-laser is less than that of CW laser, so only serrated aperture can be used to get uniform near-field uniform intensity distribution.

A laser beam automatic alignment system is applied in a multipass amplifier of the SG-III prototype laser. Considering the requirements of the SG-III prototype facility, by combining the general techniques of the laser beam automatic alignment system, according to the image relayed of the pinholes in the spatial filter, and utilizing the optical position and the spatial distribution of the four pinholes of the main spatial filter in the multipass amplifier of the SG-III prototype, a reasonable and optimized scheme for automatic aligning multipass beam paths is presented. It is demonstrated on the multipass amplifier experimental system. ?2004 Society of Photo-Optical Instrumentation Engineers.

Alignment accuracy of the cavity mirror in multipass amplifier is very high. Aiming at the requirements on alignment precision of cavity mirror in high power lasers, using image relaying of pinholes and the principle of beam automatic alignment, a scheme to align the cavity mirror is designed. It has been demonstrated on the simulation experiment system of the SG-Ⅲ prototype facility. The main amplifier's adjustment can be finished in 15min. The centering precision of the system is less than 0.5% of the beam diameter. The pointing precision of the system are less than 0.3".

Laser beam automatic alignment systems are used to align the SG-Ⅲ prototype facility laser. Considering the facility qequirement, combining the key technique of automatic alignment, according to the image relay of the pinhole, utilizing the optical position and the spatial location of the four pinholes of the main spatial filter in the four-pass beam in the SG-Ⅲ, this paper presents a reasonable scheme for automatic aligning in the four-pass amplifier, which has been fully checked on the multi-pass amplifier experiment system.The centering sensitivities of the system are less than 0.5% of the beam diameter. The pointing sensitivities of the system are less than 10μm.

The paper concerns the improvement of two primary technologies for 3ω(351nm) shot experiment in SG-Ⅱ facility target area ,which are 3ω target alignment laser and optical viewing system .The 1ω (1 053nm) laser is exported form the Nd:YLF laser and passes the KTP+BBO system to acquire the 3ω laser.And the 3ω laser is coupling-out with main laser.In order to improve the laser accurately position on the target,the reflection optical system is replaced by the transmission optical system,which avoids the effect of chromatic aberration.

Power balance between laser beams is important for high-power laser system. This paper uses a calculation method as an exact solution for laser amplification to simulate the output pulse shape of “Shenguang Ⅱ" laser facility. The results are preferable,as compared with the results of the experiments.

Based on the closed-form propagation expression of Hermite-cosh-Gaussian beams passing through an unapertured thin lens, intensity distributions in focal region were studied. Focal shifts of the beams and dependences of maximal intensity position on decentered parameter were investigated. The results show that the relative focal shifts (absolute value) in TEM_(11)-mode Hermite-cosh-Gaussian beams increase with decreasing decentered parameter and Fresnel number, and tend zero with large Fresnel number. For TEM_(22)-mode Hermite-cosh-Gaussian beams the principal maximum intensity is located off the axis when the decentered parameter is smaller than 0.54 and on the axis when decentered parameter is greater than 0.54. When decentered parameter equals 0.54, the beam has double principal maximum intensity here. The intensity is more concentrated into the axis with greater decentered papameter. Dependences of the relative focal shifts in TEM_(22)-mode beam obtained using LW and GH methods on decentered parameter and Fresnel number coincide with that of TEM11-mode beam. However , there is quantitative difference between the results obtained using the two different methods.

The system for effective area measurement of laser spot on target plane was designed based on the definition of effective area. A 12-bit CCD camera is used for the effecive area measurement. A bmp image of the beam profile is stored. This image is processing by software to evaluate the ratio of total energy and peak fluence (effective area). Some test results were given using effective area measurement system. The system was employed in the laser induced damage threshold test and it is helpful to improving the precision of laser induced damage threshold test.

Digital-speckle-pattern interferometer (DSPI) is a wide-used technology in fined-measure. Nowadays common DSPI system employs high-power laser source and great experimental facilities, which is only suitable for lab research work. In order to extend its application into fieldwork, a new optical layout for portable DSPI meter is proposed in this paper, which is suited for low-power laser and has some advantages such as optimized compact framework and small size, Driven by a He-Ne laser of 5 mW output power, it shapes fine interferogram whose contrast is as well as that shaped by laser of 20 mW power. Thus utilization efficiency of laser is promoted. Based on the study in theory and experiments, the paper demonstrates rationality of the portable DSPI meter.

The experimental studies of Ni-like Ta x-ray laser at near “water window" on Shenguang Ⅱ laser facility were reported. By using a new scheme of united driving of fundamental- and double-frequency laser, the distinct spectrum signal of Ni-like Ta x-ray laser at 4.48 nm was obtained under the total drive energy of 400J. The efficient gain-length product was about 5.5.

X-ray spectra have been produced on "Shenguang II" multi-beam laser facility, in which the flat gold target was irradiated by array lens smoothing 0.53μm laser beam. The absolute conversion efficiency ξ_x is reported from the incident laser light energy to x-ray photons for laser-produced plasmas. The characterization of backlighting line sources having photon energies from 1.8 to 3.1 kev are studied under multi-beam laser driving target condition. Quantitative x-ray spectra and energies spectral distribution have been obtained as a function of laser power density and x-ray emission angle.

For inertial confine fusion experiment, temporary pulse shaping technique is of great significance. With the development of the ICF technology,the demand of the temporary fill rate of terminal pulse is higher and higher. To satisfy the requirement of ICF experiment,by using own-designed “knife edge” apparatus and improved temporary-space transform pulse shaping technique,the pulse shaping on “Shenguang-Ⅱ” facility is realized. In the terminator,the square laser pulse with pulse width 1.16 ns,rise time 337 ps, fall time 360 ps, temporary filling factor 81.2%, is obtained. This pulse totally satisfies the requirements of the physical experiment. At the same time, some improvement is put forward to satisfy the higher experimental requirements in the future.

type of λ/4～λ/2 broadband antireflective coating has been developed by sol-gel dipping method with tetrabutylorthotitanate and tetraethoxysilane (TEOS) as precursors. This antireflective coating possesses smooth and even surface,its average roughness is estimated having the value of RMS (1.201) and RA (0.934),and the specific scratch-resistant is good. Most -OH groups are eliminated at the temperature near 200 ℃. The average transmission of both-coated K9 substrate is increased 6.6% higher than uncoated one in the spectra from 400 nm to 700 nm. The antireflective coating is expected to coat amplifier blastshields of "Sheng-Guang: facility for enhancing the pumping efficiency of amplifiers

Beam automatic alignment system is applied in high power laser facility for inertial confinement fusion. The basic principles and key techniques are researched. The evolution of beam automatic alignment systems abroad is introduced and the future development of the automatic alignment system in high power laser facility is prospected.

To achieve the laser accurately positioning on the target in high power laser facility, the error analysis method is necessary to actualize engineering of the facility and increase the technology of the correlational systems. The automatic alignment control system is mainly designed to establish and maintain laser chain alignment and eliminate the error, but the traditional error analysis method based on both contingency and system errors does not give a comprehensive analysis. So a new error analysis method based on both static and dynamic errors is developed. The optical system in the target area is analyzed with this method and a common equation of target positioning tolerance has been obtained. The satisfaction and feasibility of the error analysis are demostrated.

The noncollinear optical parametric amplification of BBO (β-BaB2O4) type-Ⅱ phase matching is theoretically investigated. The phase matching angle is calculated under different noncollinear angles. It shows that BBO type-Ⅱ phase matching has very narrow bandwidth in the simulation of the gain spectrum, which is confirmed in the numerical calculation of the parametric bandwidth. The dependence of the parametric conversion efficiency on the crystal length is simulated. The effects of the non-synchronization of the pump-pulse and signal-pulse and the shape of the incident signal-pulse on the parametric conversion effciency are also discussed. The parametric conversion efficiency has a maximum of 25% corresponding to the optimized crystal length and synchronization. The results indicate that BBO type-Ⅱ phase matching has very narrow parametric bandwidth and gain bandwidth. The approach is useful to the study of the narrow band optical parametric amplification. It also makes BBO crystal more useful in the optical parametric amplification.

For precision SG-Ⅱ power balance, there must have same output energy and output pulse waveform in the 8 beams, it means that the gain and transmissivity in every amplifier chain are same. But the gain abilities of the same type amplifiers in 8 beams are different for needing of daily operation. It was a first time that small signal gain of different amplifiers in SG-Ⅱ were measured online by using a small energy measurement system which has superior 1% precision. The small signal gain values of 40 and 70 rod amplifiers, 100 slab amplifiers and 200 double slab amplifiers are got in the regular working voltages. The differences of the same type amplifiers are quantized and that provides valuable experimental data to power balance in SG-Ⅱ precision.

Starting from Huygens-Fresnel diffraction integral formula, propagation expression of pulsed Bessel beams with Gaussian spectrum in frequency domain is obtained. By using Fourier transform, propagation formula of the beams in temporal domain is derived. Based on the formula, propagation properties of the beams in free space are studied through numerical calculations. It is found that bandwidth of pulse has effects on time delay and pulse width. As bandwidth broadens, the time delay increases and temporal waveform changes, which results in increasing of pulse width. The time delay and pulse width also depend on propagation distance. Both of them increase when propagation distance increases.

A laser alignment system is applied to a high power laser facility for inertial confinement fusion. A design of the automated, close-loop laser beam alignment system is described. Its function is to sense beam alignment errors in a laser beam transport system and automatically steer mirrors preceding the sensor location as required to maintain beam alignment. The laser beam is sampled by a sensor package, which uses video cameras to sense pointing and centering errors. The camera outputs are fed to a personal computer, which includes video digitizers and uses image storage and software to sense the centroid of the image. Signals are sent through the computer to a stepper motor controller, which drives stepper motors on mirror mounts preceding the beam sampling location to return the beam alignment to the prescribed condition. Its optical principles and key techniques are given. The pointing and centering sensitivities of the beam alignment sensor package are analyzed. The system has been verified on the multi-pass amplifier experimental system.