KEYWORDS: Charge-coupled devices, Vacuum, Vacuum chambers, Control systems, Thermal effects, Pipes, CCD cameras, Instrument modeling, High power lasers, Temperature distribution
Charge Coupled Device(CCD) in vacuum environment could be easily overheated, and the energy is not equally distributed on the surface. So the thermal design of the CCD plays a significant role in the procedure of the whole detection[1]. If a proper method is used for the cooling of the CCD, the temperature distribution would be more equally on the surface and the testing result of the CCD would be more accurate. In this paper, a thermal control system for CCD camera in vacuum was designed. CCD will be placed in a cavity filling with high-specific heat capacity gas, so that the energy generated from CCD could be reserved in the gas through thermal convection and heat radiation. In order to reduce the gas leakage, multilayer cavity was designed to maintain the gas pressure of the cavity. The result shows that the optimized multilayer cavity structure for cooling system of CCD can reduce overheated of CCD significantly with CFD (Computational fluid dynamics) method.
Motivated by the need to reduce the deformation of the large clear aperture transmitting mirror in the high power laser facilities (SG-II), a novel support scheme is presented for transferring maximum deformation area from the center of clear aperture to the edge of a transmitting mirror. The optimum preload force applied to the small flexure deformation on the edge is determined based on elasticity theory and finite element analysis. Experimental results show that the preload force applied to the edge of the mirror can offset the deformation of the aperture caused by gravity. The Peak to Valley (PV) value and Root-Mean-Square (RMS) value of the clear aperture of optics reduced by 71.9% and 82.7%, respectively, when preload force is applies, compared to their values without any preload force. The proposed method would facilitate the development of new support schemes for large aperture mirrors, especially transmitting mirror.
Realizing the main amplification system without window glasses is important for high-power laser devices. Not only optical components and B-integration of the system are reduced, but also the output capability and beam quality of the system are improved. While the primary problem is how to maintain the cleanliness after the window glasses being removed. In response to this problem, this paper proposes a cleanness control scheme suitable for realizing the windowless operation of the main amplification system.Take one main amplification system of a high-power laser device for example, some work are conducted: integrated design of optical pipelines, introduction of air knives, and simulation analysis of airflow field and related parameters. The integrated design of the beam tubes makes the entire main amplification system to maintain a closed environment.The air knife which can generate a high-speed air curtain and block the exchange of airflow, divides the entire system into three parts: main amplifiers, beam tubes, other optical components. For each part, we use in-situ control to achieve cleanliness. To beam tubes and main amplifiers, theoretical analysis and verification of gas flow field characteristics for different process parameters are conducted. For other components, the effectiveness of air knife air curtain protection has also been experimentally studied and analyzed. Finally, it provides important guidance for realizing the remove of the window glasses of the main amplification system.
The latest progress on high power laser facilities in NLHPLP was reported. Based on a high power laser prototype, damage behavior of 3ω optics was experimentally tested, and the key influencing factors contributed to laser-induced damage in optics were deeply analyzed. The latest experimental results of advanced precision measurement for optical quality applied in the high power laser facility were introduced. At last, based on the accumulated works of 3ω elements damage behavior status in our laboratory, beam expanding scheme was presented to increase the total maximum output 3ω energy properly and decrease the laser induced damage risking of ω optics simultaneously.
Deformation of the large aperture mirror caused by the external environment load seriously affects the optical performance of the optical system, and there is a limit to develop the shape quality of large aperture mirror with traditional mounting method. It is effective way to reduce the optical mirror distortion with active support method, and the structural-optical integrated method is the effective means to assess the merits of the mounting for large aperture mirror. Firstly, we proposes a new support scheme that uses specific boundary constraints on the large lens edges and imposes flexible torque to resist deformation induced by gravity to improve surface quantity of large aperture mirror. We calculate distortion of the large aperture mirror at the edges of the flexible torque respectively with the finite element method; secondly, we extract distortion value within clear aperture of the mirror with MATLAB, solve the corresponding Zernike polynomial coefficients; lastly, we obtain the peak-valley value (PV) and root mean square value (RMS) with optical-structural integrated analysis . The results for the 690x400x100mm mirror show that PV and RMS values within the clear aperture with 0.4MPa torques than the case without applying a flexible torque reduces 82.7% and 72.9% respectively. The active mounting on the edge of the large aperture mirror can greatly improve the surface quality of the large aperture mirror.
Thermal recovery uniformity is key factor on high energy laser device. Based on the principle of statistics, combined
with the amplifier glass neodymium thermal recovery research results, we put forward degree of uniformity as evaluation
index for Nd-glass laser slab on multi-segment amplifier. The simulation results show that the heat transfer coefficient of
the Nd:glass laser slab on the amplifier is affected by number, pitch and diameter of the inlet jet. The heat transfer
coefficient and temperature contour of Nd:glass laser slab are obtained based on numerical simulation. Moreover, the
degree of uniformity of Nd-glass laser slab is on the base of simulation results. The more the degree of uniformity is
close to 1, the better thermal recovery of Nd:glass laser slab.
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