The grating tiling technology is one of the most effective means to increase the aperture of the gratings. The line-density error (LDE) between sub-gratings will degrade the performance of the tiling gratings, high accuracy measurement and compensation of the LDE are of significance to improve the output pulses characteristics of the tiled-grating compressor. In this paper, the influence of LDE on the output pulses of the tiled-grating compressor is quantitatively analyzed by means of numerical simulation, the output beams drift and output pulses broadening resulting from the LDE are presented. Based on the numerical results we propose a compensation method to reduce the degradations of the tiled grating compressor by applying angular tilt error and longitudinal piston error at the same time. Moreover, a monitoring system is setup to measure the LDE between sub-gratings accurately and the dispersion variation due to the LDE is also demonstrated based on spatial-spectral interference. In this way, we can realize high-accuracy measurement and compensation of the LDE, and this would provide an efficient way to guide the adjustment of the tiling gratings.
In a high-energy chirped-pulse-amplified laser system, grating tiling technology provides an effective means to increase the aperture of the gratings and to scale the energy and irradiance of short-pulse lasers. The difficulties lie in controlling tiling errors accurately between the sub-gratings and keeping long time stability. In this paper, a two-pass full-tiled grating-compressor (TGC) with real- time control unit is developed for the first time. The far-field distributions of the 0th order and -1 st order diffracted beams of the two pairs of tiled gratings are monitored by the same CCD system, with the main laser chain being not disturbed. In this way, we realize online real-time control of tiling errors. Through a method of locking the far-field image to compensating the temporal drift, we can realize the automation of the assembly. The TGC has successfully applied in the multi-function XGIII laser facility, and focusing focal spot and output pulse width are obtained.
Array element tiling is one of the key technologies for the coherent beam combination in a high-power laser facility. In this paper, we proposed a method of the array element auto-tiling based on capacitive displacement sensor. The method was verified on a double-pass tiled-grating compressor in XG-III laser facility. The research showed that the method is an effective way to control the misalignment errors automatically, with high precision and long-term stability.