In order to solve the problems of large surface figure errors in large value, high spatial frequency and multi-aberration modes which are beyond the dynamic range of the interferometer, and the problems of slow iterative convergence and high non-convergence rate of existing adaptive compensation optimization algorithm, an adaptive wavefront interferometry utilizing convolutional neural network(CNN) for large surface figure error is proposed, based on the existing adaptive compensation interference detection methods. This paper first introduces the aberration regulation principle of spatial light modulator (SLM), and sets up a convolutional neural network. Then, SLM is controlled to generate Zernike aberrations with different coefficients. Combined with Zygo Verifire interferometer, the corresponding far-field light intensity is collected to compose a labeled data set to train CNN. Finally, a large surface figure error coefficient prediction experiment is carried out with the trained CNN, and the aberration compensation is performed according to the prediction coefficient to verify the effectiveness of the method. The experimental results show that the dense fringes can be transformed into resolvable fringes with this method, and the resolvable probability of full-diameter fringes after compensation is 66.7%. This method is able to greatly improve the performance of adaptive compensation detection, thereby meeting the demand for high dynamic range interference detection technology in the ultra-precision optical surface manufacturing process.
In the three-dimensional(3-D) microscopic measurement based on white light interference imaging, due to the influence of external environment interference and the phase-shifting step size of micro-shifter, the sampling signal by longitudinal scanning may have the problem of "peak leakage", which seriously affects the accuracy of measurement results. In this paper, by analyzing the spectrum of interference signal, a method for extracting zero optical path difference(OPD) position based on multinomial Gaussian fitting for envelope curve of filtered time domain signal is proposed. Finally, based on the method proposed in this paper and ZYGO commercial interferometer, the comparative measurement experiment of standard steps is carried out. The simulation and experimental results show that the method has good robustness and effectiveness.
With the expansion of military master and the adjustment of military scale structure, new requirements have been put forward for talent cultivation, especially for the high-level applied talents cultivation. Talents with different specifications, types and levels must be cultivated in the education process. Therefore, the master cultivation mode needs to be explored and improved. This paper systematically studies the classification standards, training scheme, graduation standards in the classification cultivation mode for master majoring in precision optical engineering, as well as the feasibility and implementation suggestions of the classification cultivation for master in military academy. By means of field investigations, collection and arrangement of network resources, questionnaire survey of characteristic samples, and combining with data resources of master, the sample database is established by collecting relevant data including professional types, training scheme, dissertation quality, professional development prospects and post applicability to output talents. The results indicate that the quality of graduate training can be effectively improved by the classifying training mode of “academic” and “applied”. The classified cultivation can not only satisfy the reform and development trend of military academy and the diversified demands of modern war for military talents, but also provide reference for high-level innovative military talents cultivation.
To meet the requirements of high performances of linear guideway, an aerostatic lubrication model (ALM) with orifice restriction is put forward with finite difference method based on the bearing of slider block. With the combination of flux-error feedback and grids parameter optimization, the model is solved and the static behaviors of the bearing are obtained, and the bearing configurations, such as the diameter, number and position of the orifice are optimized. Finally, the performance test of the linear guideway is carried out, and the theoretical results have a good agreement with the experimental data. The actual stiffness and linearity of the system are 59N/μm and 0.3μm/255mm respectively. The conclusions are useful for the design and analysis of high precision aerostatic equipment.
Traditional methods of measuring out-of-squareness of ultra-precision motion stage have many limitations, especially the
errors caused by inaccuracy of standard specimens, such as bare L-square and optical pentaprism. And generally, the
accurate of out-of-squareness measurement is lower than the accurate of interior angles of standard specimens. Based on
the error separation, this paper presents a novel method of out-of-squareness measurement with a polygon artifact. The
angles bounded with the guideways and the edges of polygon artifact are measured, and the out-of-squareness distraction
is achieved by the principle that the sum of internal the angles of a convex polygon artifact is (n-2)π. A out-of-squareness
metrical experiment is carried out on the profilometer by using an optical square brick with the out-of-squareness of
interior angles at about 1140.2 arcsec. The results show that the measurement accuracy of three out-of-squareness of the
profilometer is not affected by the internal angles. The measurementwith the method can be applied to measure the
machine error more accurate and calibrate the out-of-squareness of machine.
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