In recent years, the Chinese optical industry has been growing with an amazing speed, in the forms of joint ventures, private enterprises and government supported investments. The current status of optical design and fabrication in China is outlined. Optical design software packages commonly used in the country are listed and their features summarized. Example manufacture capacities are given for typical companies in areas including optical glasses, lens elements and commercial products such as telescopes, microscopes, camera lenses, etc. Recent developments such as aspheric lens fabrication and diffractive element study are briefed. Efforts made in Beijing Institute of Technology to promote closer and more convenient international cooperation in optical industry are described.
The newest achievement of super smooth processing technology of optical element bowl-feed polishing (BFP) is described. The need background and developing tendency of super-smooth optical elements are analyzed. The key problems of BFP have been found, the process parameters have been determined, and the basic method of BFP has been worked out by the study of process factors and processing principle. Φ50 mm k9 glass sample with 0.5 nm surface roughness and better than λ/8 surface shape has been processed.
Some important progresses in Chinese optical manufacturing technology in the 20th century were reviewed in three development stages. Then the present situations of Chinese optical manufacturing of binocular and camera were shown. At last, six main trends of manufacturing technology of optical elements in the early 21st century were given, considering the national conditions.
In this paper, the authors present a new technique which through electrolytic truing, could use metal bonded supermicro diamond wheel to machine optical glasses and obtain optical surfaces with best-quality finish. Using this technique to machine K9, F4 and zerodur, the surface roughness Ra could reach a value less than 10 nanometer and a planeness less than 1 μm. In addition, the authors have also studied some phenomena occurred in the grinding process.
The recent development and application of the technique of using zone plate interferometry to test aspherical surfaces are summarized. The advantages and disadvantages of several types of zone-plate interferometer are given. The principle and method for testing aspherical surfaces using a modified zone-plane (MZP) are described. The relation between installation of MZP and measurement precision is analyzed. The design of MZP is modified to eliminate the curvature at the border of the interference pattern. At last, some experimental results are given.
In the methods to test an asperhical optical surface, sheering interferometer is a testing instrument by which the wavefront of the surface testing is split apart into two and then interference fringes can be formed without demanding a standard reference aspherical wavefront. However, if the sheering interferometer is applied to test an aspehrical surface, having a relatively big deviation from its best fit spherical surface, the fundamental measuring error will increase very quickly. A comprehensive analysis of this error is given and an improved method is put forward by which the testing scale of the sheering interferometer is enlarged by introducing an analogue standard wavefront produced by a computer so as to reduce error resources and to improve the testing accuracy.
An interferometric system for aspheric surface testing is described. The system consists of a lateral shearing interferometer with a polarization phase shifter, CCD camera, a video frame grabber and a computer. A key element of the interferometer is a plane parallel birefringent plate which can give any amount of lateral shear. Phase shifting interferometry is used to obtain the derivative information of the wavefront under test. By integrating the derivative data, we have the wavefront shape. The system has measured surfaces with rms repeatability of better than (lambda) /20.
An interferometric optical profiler using Nomarski microscopy has been developed for measuring surface roughness and 3-D profiles. A commercial Nomarski differential interference contrast (DIC) microscope is modified to add a quarter-wave plate for phase- shifting. Quantitative slope data can be obtained by utilizing phase shifting techniques that rotate the analyzer to change the phase difference between the two orthogonally polarized beams. The slope data is integrated to generate surface height. The instrument is insensitive to vibration. It has measured surface features with a repeatability of better than 1 nm in an ordinary laboratory environment without vibration isolation.
Using a small polisher with a specific movement to figure the optical surface under the control of a personal computer not only can one locally figure the surface precisely to improve the image quality of optical elements but also can figure the aspherical surface, beginning with the closest spherical surface, if the departure between these two surfaces is not large.
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