Purpose -The purpose of this paper is to describe a strap-down image stable strategy for multi-load optoelectronic imaging platform hung below a tethered aerostat. Design/methodology/approach -Four two dimension pods, each with a visible light camera, are fixed on the optoelectronic platform. A POS (Position and Orientation System) is used to acquire the attitude rate data of optoelectronic platform, while the data can be coupled to the pods' servo systems through corresponding coordinate rotation, then the motors of pods will adjust the line of sight to the opposite way to keep the stabilization of image exported by visible light camcorders. Simultaneously, two rate gyros are installed at the inner frame of each pod, which are used as a backup to avoid the failure of POS. Findings -Using one attitude and position measurement system can realize the stabilization of multi optoelectronic pods, which is same as or even better than the ratio gyro stabilization. Research limitations/implications -As the tethered aerostat is a flexible body, it is affected a lot by the wind speed and wind direction at the low height (,1,000 m), which leads to the motors of pods always adjust the line of sight to the mechanical limiting of pods. Practical implications -Strap-down stabilization technology has been successfully used in the tethered aerostat monitoring platform to surveillance Shanghai World EXPO site. Long time experiments verify the feasible and effective of the multi-load stabilization technology. The impact on the image by the adjustment of servos is less than 10 percent of the whole view of sight. Originality/value -The paper introduces a strap-down stabilization technology for multi-load tethered aerostat platform, which is more suitable to be applied in the platform of relatively minor attitude change, like the airborne multi-load platform and multi-load UAV (unmanned aerial vehicle) platform.

The corrosion behaviors of the ArF excimer laser copper alloy electrodes were studied. The morphology, composition and impurities were characterized by optical microscope, scanning electron microscopy, electron microprobe and glow discharge mass spectrometer methods. The anode produces the reef, the corrosion pits, the hole layer and the $1{-}10~\unicode[STIX]{x03BC}\text{m}$ level flake impurity. The cathode produces the particles, the sputtering pits, the element reduce layer and the $1~\unicode[STIX]{x03BC}\text{m}$ level particle impurity. Besides the Cu element, other elements in the alloy participate in the corrosion: Al element in the reef is over 1.5 times of the anode, Zn element in the particles is 1.3 times of the cathode, many trace elements congregate on the copper surface several and even hundreds of times. These elements are responsible to a great degree for the impurities and the rapid energy decline of the long-time idled laser.

Abstract. In this paper, the internal flow field in an optical module of DUV laser was analyzed by ANSYS Fluent based on the finite volume method. The way of purging nitrogen was optimized according to the results of the analysis. After the optimization, a better nitrogen purge method was obtained, and a flow field with uniform velocity and low turbulence energy was obtained on the laser transmission path. The results of this paper can provide a reference for the design of the gas purge system of DUV laser.