An off-axis three-mirror detection system with a large field of view is designed in order to improve the space target detection capability. The optical system is a Cook-TMA with the focal length of 127mm, the F number of 2, the field angle of 25° × 25° and the spectral range of 400-700nm. The primary mirror and the tertiary mirror of the off-axis three mirror system are all designed by free form surfaces: the primary mirror is characterized by Zernike polynomial and the tertiary mirror is described by XY polynomial. At the same time, we analyze the related characteristics of Zernike polynomial and XY polynomial. The results show that the free form surfaces have great advantages in improving the field of view and the imaging quality of the off-axis optical system. The system has high energy concentration and good imaging quality, which can capture and track the target in a wide range is suitable for wide area target monitoring.
According to the existed method of positioning paraboloid surface workpiece for measuring its shape accuracy, this paper proposes a new method of positioning paraboloid surface workpiece with zero error sums. The key idea of new method is to consider whole workpiece surface comprehensively, which can appreciate whole workpiece surface reasonably, objectively and entirely. It is different from former measuring methods mainly considering several points with big errors. The new method is important for elements used in a optical system, since in optical system the main factors of affecting optical system characteristic are not only several points with big errors on optical element surface, but also the whole surface. It is favorable to improve workpiece surface shape accuracy and its optical characteristics. Its principle not only can be used in measuring paraboloid but also for measuring other aspheric surface.
This paper discusses a new lapping hyperboloid method, which combines high-speed lapping technology with solid abrasives and lapping tool bending method. In this method a bending moment is acted as a lapping tool with solid abrasives, which makes it bend and form a shape on its working surface, which is similar as the generating line of workpiece surface. In lapping, the lapping tool is coaxial with the axis of hyperboloid surface of the workpiece and the lapping tool rotates around it to lap. This kind tool is used in forming lapping on a high speed lapping machine.
The principle of solid abrasives lapping is that the abrasives are fixed and made into a special lapping tool; the workpiece is lapped in high speed lapping machine tool. It possesses many advantages compared with traditional low speed lapping with particulate abrasives, e.g. high machining efficiency, low machining cost, high and stable machining accuracy. So the highly efficient lapping method has been paid close attention to. This paper made a study on surface micro topography of different material by solid abrasive lapped at high speed. In experiments the lapping technique parameter is fixed, and different workpiece which are made by T10 steel, carbide, ceramic glass and alumina ceramics are lapped. The surface micro topography is measured by SEM, from the measuring result, it can be known that there is some shallow scribe on the surface of T10 steel, and the obvious plastic deformation can be observed. The SEM pictures show that there is some scribe on the surface of ceramics glass after lapped, with more magnification times many micro cracking and some plastic hump can be observed on the scribe. These scribes and humps are first cause of depressing surface quality, and these micro cracking can result in a lot of diffuse reflection on workpiece surface, it decreases the glossiness of mirror surface. On the surface of alumina ceramics there are a lot of defects, the size of such defect is more than the scribe of abrasive, it can be sure that the defect is not produced by lapping, so the material quality is an important effect fact to surface macro topography. On the surface of carbide there are a little of scribe and air cavity, and the scribe is very shallow; the defect of powder metallurgy martial is the primary reason.
This paper discusses a new lapping paraboloid method which combines high speed lapping technology with solid abrasives and lapping tool bending method. In this method a bending moment is acted on lapping tool with solid abrasives, which makes the tool bend and form a shape on its working surface which is same the as generant of workpiece shape. This kind of tool is used to form lap.
This paper discusses some problems about nanometer lapping photonics elements. The solid abrasives high speed lapping method and the theory of lapping tool wearing uniformly are used in machining photonics elements. It makes workpiece machined surface roughness reach to Ra0.88nm, flatness reach 19nm. That not only realizes nanometer machining, but also realizes machining at high efficiency and low cost.
This paper studies the effect of abrasives size on machined workpiece surface in solid abrasives lapping. From the results it can be seen that the value of roughness of the machined workpiece surface increases as the size of abrasives increases. Its principle is same as ultraprecision grinding and tradition lapping. But for same size abrasives, the results got in this paper is better than them in ultraprecision grinding and tradition lapping. In this paper, the roughness of machined workpiece surface can reach Ra2.83 nm, by using the abrasives which size is 3.5μm.
This paper discusses lapping a metal mirror with solid abrasives at high speed. In this method there are three procedures. First the workpiece is ground in a grinding machine, which makes the surface roughness of the workpiece reach about Ra1.6micrometers . Second the workpiece is lapped roughly on a lapping machine, which makes the surface roughness of the workpiece reach about 0.1micrometers . Last the workpiece is lapped finely, which makes the surface roughness of the workpiece reach about Ra1nm. Because solid abrasives are used, the machining efficiency is very high. Each lapping procedure time is only about one minute. A high speed, high efficiency and accuracy machining is realized.