Planar laser-induced fluorescence (PLIF) has been widely used in the two-dimensional (2D) accurate measurements of important combustion parameters such as temperature, species concentration and flame structure due to its high spatiotemporal resolution and non-contact diagnosis. Since the sheet-forming optics is an important part of PLIF system, the accuracy and precision of PLIF measurement strongly depend on the uniformity and focal-depth of the shaped sheetbeam. However, the current sheet-beam shaping methods cannot meet the practical requirements of high uniformity and long focal-depth at the same time. To improve the measurement accuracy and precision of PLIF technology, a new sheetforming homogenization optical system with long focal-depth is proposed and designed based on aspherical aberration effect. By redistributing the central energy of Gaussian beam to the edges of the shaped sheet-beam, the sheet-beam shaping with high uniformity is realized. The working wavelength of the system is 283.553 nm, the working distance is 504 mm, and the total length of the system is 360 mm. The design results show that the size of the shaped sheet-beam is 100 mm × 0.5 mm with the effective focal depth of ±15 mm, the maximum beam uniformity >89% and the energy transmission efficiency >95%, which can better meet the actual requirements of PLIF measurement.
Aiming at tracking and attacking low altitude, slow and small targets with high power laser, a miniaturized high power laser beam emitting and tracking aiming system is designed to meet the requirements of compact type. In the beam emitting part, the single coude mirror is used to realize the waveguide system of laser beam in pitch direction. The structure is compact, which meets the requirements of miniaturization and reduces the difficulty of realization. In the pointing and tracking part, the tracking dynamic performance is improved, based on the compound-axis tracking strategy and combined with the man in the loop dynamic correction of the coarse tracking residual. The stability of the optical axis of the single coude mirror is better than 5μrad. The field test results show that the tracking accuracy of the system is 6 μrad for balloon and 9μrad for small quad-rotor unmanned aerial vehicle, which verifies the feasibility of the design of beam emitting and tracking system.
The damage mechanism and application between intense pulsed laser and non-metallic materials have been regarded as the research hotspot in recent years. The ceramic materials have the advantages of high temperature resistance, corrosion resistance, good chemical stability and high temperature mechanical properties, and insensitivity of bonding strength to high temperature. Therefore, ceramics are considered to be a good choice for laser-resistant materials. In this paper, the damage topography and anti-damage properties of high absorption ceramic coatings induced by pulsed laser at different energy densities are investigated from macro and micro levels. Then, combined with the experimental results of absorptivity, the lower limit of damage threshold (better than 8J/cm2) for the ceramic coatings is obtained. Finally, the main factors affecting the pulsed laser resistance of ceramic coatings are discussed. The results of this study can lay an important experimental foundation for the further research on the damage mechanism of intense pulsed laser and ceramic coating materials.
An Infrared Imaging Pretreatment System was designed based on Xilinx Zynq-7000 Extensible Processing Platform (EPP). Zynq-7000 integrate a dual-core ARM Cortex-A9 based processing system (PS) and programmable logic (PL) in a single device. In this design, PL was developed for IRFPA video signal acquisition, and used VIDEO_IN, VIDEO_OUT, AXI-VDMA IP core to build high speed data channel between PS and PL. PS was developed for Imaging Pretreatment such as Non-uniformity correction, Blind pixels compensation and Image enhancement, using DDR3 for PS’ external memory and PL for Camera Link/PAL video output. It’s optimized for powerful, high real-time, small size, low-power and high reliability, to reach the goal of mass production in work.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.