DEVELOPMENT ON HIGH-ACCURACY FABRICATION TECHNOLOGY OF ASPHERIC OPTICAL COMPONENTS USING THE PARALLEL GRINDING METHOD

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Development of the manufacturing technology for high-accuracy convex aspheric glass lenses: The objective of this sub-project was to fabricate the convex aspheric lens made of glass, 20〜150mm in diameter, having a form accuracy of 100 nm and a surface roughness of lOnm. This kind of lens is used in the optical systems such as data projector. The main results are listed as follows: (1) The ultraprecision aspheric grinder AHN60-3D, produced by the Toyada Machine Co., Ltd. was renovated for the use of the parallel grinding method. (2) The software, which is able to generate the NC codes from the aspheric equations according to the parallel method, was developed. (3) Based on the traditional CG (Curve Generating) method, high-accuracy truing technology far spherical wheels was developed, and it has become possible to contour the spherical diamond wheel, 75mm in diameter, SD600〜SD5000 in mesh number to an form accuracy of 1 micrometer. (4) The diamond wheel for ultraprecision grindinof asph … More eric glass lenses were developed by changing the material properly of the resin bind, filler type and blowing agent etc.. As a result, 30nmRy surface roughness and 100 nm form accuracy were realized in Use final grinding experiments. This provides the possibility of obtaining ultraprecision aspheric surface on glass without polishing. (5) The grinding experiment of the 150mm-diameter aspheric glass lens was performed. It was proved that, using the parallel grinding method, the ultra-precision grinding is possible even for large radius lenses, since the grinding wheel wear during one grinding pass is as small as can be neglected.Development of the manufacturing technology for concave aspheric mold and micro aspheric mold made of cemented carbide: The objective of this sub-project was to produce the molds of aspheric lenses for CCD cameras and endoscopes. The main results are listed as fellows: (1) According to the minimum curvature radius of the micro aspheric surface to be ground, spherical resin-bond diamond wheels, 1mm in diameter, 600-3000 in mesh number, were designed and manufactured. (2) An on-machine truing method for micro spherical wheel was developed by utilizing a stainless steel pipe as the lap tool. A 1mm-ditmeter grinding wheel was successfully dressed to a spherical shape by using the above method. (3) Cemented carbide mold of aspheric lens for endoscopes applications were ground using the proposed method. 50mmRy surface roughness and 100 nm form accuracy were obtained on a 2mm-radius aspheric lens mold. (4) An on-machine measurement system having an air-micro-probe was designed and developed. The system can perform measurement at l0nm resolution and l0mm dynamic range. (5) Theoretical analysis and simulation of the error formation mechanism of the arc-truing device was carried out with considering the offset errors in X direction, Y direction and the wear of the grinding wheel. An error compensation method was developed. As a result, 100nm form accuracy was obtained. Less