The removal function in machining is not an ideal impulse function, and the material removal at any point on the workpiece is a superposition of the removal at that point from the distribution of removal at surrounding points. When the residence time suddenly jumped to zero at the edge, the removal function and the residence time convolution results will gradually decrease at the edge, the removal matrix at the edge of the formation of the "collapse", after many convolution iterations, the edge of the face shape of the error convergence rate is lower than the other positions, resulting in edge effects. This paper firstly put forward an iterative algorithm based on the residence time of the cylindrical projection, and then analyze the edge effect in the iterative algorithm, and put forward two methods to suppress the edge effect, and select different removal functions and the form error on the algorithm to carry on the simulation calculation. Finally, the results of machining of mold #54 verifies the effective suppression of edge effect error by the method in this paper.
EP satellite is a scientific exploration satellite for time-domain astronomy and high-energy astrophysics, its function is to carry out high-energy transitory celestial body survey with the highest sensitivity in the soft x-ray band. EP will be equipped with two groups of x-rays focusing mirrors (each group contains 54 Wolter-I mirrors). An x-ray focusing mirror is used to collect x-ray radiation in the universe, and is the core component of an x-ray astronomical satellite observation payload. The current x-ray focusing mirrors are derived from the Wolter-I reflector, and the light is focused through the inner surface. The inner reflection surface is an optical free-form surface connected by parabolic and hyperbolic surfaces. Many conventional measurement methods are not applicable and difficult to measure. High precision contact measurement is easy to scratch the mirror surface, Therefore, non-contact measurement must be used. In this paper, we develop two non-contact surface precision measurement devices are developed to solve the problem of difficult measurement of the inner reflection surface of the x-ray focusing mirror. One is a rapid measurement device based on the principle of optical star measurement method, The other is to measure the mirror inner surface by a single point scan measurement, the optical triangulation method is selected as the principle of the measurement device. We then verified the measurement accuracy of the mirrors with a precision visible light test system. In order to further verify the measurement accuracy of the focusing mirrors, x-ray testing of the focusing mirror was carried out at the 100-meter vacuum x-ray calibration facility of the Institute of High Energy Physics, Chinese Academy of Sciences. The x-ray measurement results are better than the project index requirements.
EP satellite is a scientific exploration satellite for time-domain astronomy and high-energy astrophysics, its function is to carry out high-energy transitory celestial body survey with the highest sensitivity in the soft X-ray band. EP will be equipped with two groups of x-rays focusing mirrors (each group contains 54 Wolter-I mirrors). An X-ray focusing mirror is used to collect X-ray radiation in the universe, and is the core component of an X-ray astronomical satellite observation payload. The current X-ray focusing mirrors are derived from the Wolter-I reflector, and the light is focused through the inner surface. The inner reflection surface is an optical free-form surface connected by parabolic and hyperbolic surfaces. Many conventional measurement methods are not applicable and difficult to measure. High precision contact measurement is easy to scratch the mirror surface, Therefore, noncontact measurement must be used. In this paper, we develop two non-contact surface precision measurement devices are developed to solve the problem of difficult measurement of the inner reflection surface of the X-ray focusing mirror. One is a rapid measurement device based on the principle of optical star measurement method, The other is to measure the mirror inner surface by a single point scan measurement, the optical triangulation method is selected as the principle of the measurement device. We then verified the measurement accuracy of the mirrors with a precision visible light test system. In order to further verify the measurement accuracy of the focusing mirrors, X-ray testing of the focusing mirror was carried out at the 100-meter vacuum X-ray calibration facility of the Institute of High Energy Physics, Chinese Academy of Sciences. The X-ray measurement results are better than the project index requirements.
Based on chemical-mechanical polishing and combining mechanical and tribochemical polishing techniques, a precision lapping method suitable for parabolic polishing specified by grazing incident X-rays is introduced. Various factors affecting the polishing process are analyzed, and the results show that the proposed method is consistent with Preston's equation and Hertz contact principle. Therefore, this paper proposes a general material removal model based on the above two methods. The mid and high-spatial frequency errors are demanded to reach the requirements with an angular resolution consistently < 6 arcsec HEW and a roughness of 0.3 nm rms (between 1 mm and 0.002 mm spatial frequency range). To achieve the conformal ultra-smooth polishing of focusing mirrors, the process of full-aperture super-smooth pitch polishing is investigated. The influences of key polishing parameters are revealed. The evolution of the surface topology has been studied. A polishing setup is established to carry out experimental polishing to verify the optimum processing parameters obtained by simulations and previous polishing tests. Besides, the effect of abrasive particle size on the roughness is also verified. The roughness of the polished mandrel is measured at different positions, and the optimum roughness reaches Ra 0.359 nm. The polishing approach can significantly reduce the surface roughness of the replication mandrel, satisfying the low energy band focusing requirement of grazing incidence X-ray mirrors.
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