Research On Correcting Of The Grating Groove Error In Large Area And Real-time Montoring Technology

For a large-area and high-quality plane diffraction grating, especially an echelle which has become a new hot spot in spectrograph field, and it is very popular for military, astronomy, defense, and civilian applications. Because of deep grooves with strict shapes, echelles and infrared-laser gratings are still produced by mechanical ruling. The grating ruling machine major components are the ruling system and the feeding system, and the errors of above system impact on the grating groove directly, at the same time it will influence the grating spectrum performance. In this case, the manuscript which is funded by National R&D Projects for Key Scientific Instruments and 973 project, that is focused on the grating groove errors and explore the method to improve the grating quality with large areas. Firstly, we use Fresnel-Kirchhoff diffraction theory to establish an imaging mode when the grating have groove position error and groove curve error, at the same time analyses the influence of the spectral properties with above errors. The result shows that the groove curve error and groove position error predominately influence grating sagittal and meridional spectral performance separately. These theories and research findings provide a theoretical direction of grating fabrication technology. Secondly, analyzing and optimizing the drive structure of ruling system, and in order to reduce the deformation of quartz surface, we choosing single rod to replace the double rod. Thirdly, according to lever principle, we analyses the unstable problem of the ruling carriage system, and design an improvement program of the ruling carriage system, which is using bilateral flexible hinge structure instead of the fixed link way between the saddle slider and the ruling carriage system. Then we carry out the experiments which are moving stability and ruling grating and the results show that these theories and research findings provide a theoretical and technical support for improving the quality of the grating ruling machine. Fourthly, using Ansys and abaqus software to optimize the relation between the configuration parameter of the grating ruling machine and the yaw error of the grating blank carriage, in this case we designed a structure with double piezoelectric devices to correct the yaw error. At the same time, to evaluate the correcting ability of the structure, we propose relative optical testing structure to verify the correcting accuracy by experiments. The experiment result shows that our method can accomplish the correction of yaw error in real-time effectively, at the same time it can improve the grating quality. Fifthly, establishing a mathematics model to compensate the grating blank error, and using active control technology to achieve error correction in real time. In this case we also can improve the grating quality. Sixth, basing on the imaging theory of grating spectrum, we get the computational formula of the diffraction spectrum distribution and provided a method basing on Rayleigh criterion to monitor the grating resolution in real time. Carry out the experiment to rule two gratings with and without errors correction by the real-time monitoring system respectively, the experimental turns out the feasibility of the real-time monitoring system. The method introduces the grating quality to the real-time monitoring system, in order to improve the ruling efficiency.