Study On The Manufacturing Technology Of Large-aperture Spherical Chalcogenide Glass Lens With Hole

Chalcogenide Glass, which is an inexpensive and environmental material with excellent optical characters, has been widely used in the IR optical system in recent years. Unfortunately, it is very difficult to be processed into lens because of the high coefficient of thermal expansion, especially for the large-aperture lens. It is cracked easier than the smaller one, and the surface shape accuracy corrected very hard. Therefore, study on the manufacturing process of the large-aperture chalcogenide glass lens is really great and very meaningful.The application and precision manufacturing technology of Chalcogenide Glass Lens were introduced. Meanwhile, the manufacturing process of Large-aperture Spherical Chalcogenide Glass Lens(LSCGL) with hole will be discussed in the paper.1) The material properties of Chalcogenide Glass were studied. The parameters include large-aperture, high precision surface figure and the complex structure lead to the LSCGL is machined very difficult. A technical proposal that classical polishing method with Numerical Control(NC) machining was proposed, and the machining process of LSCGL was design.2) The mechanism of abrasive and polishing were introduced, and the machining allowance was determined. Base on the analyses of principle of single swing polishing method, a kinematic equation was established. The kinematic trajectory of single swing polishing method was simulated via Matlab program, and the main parameters which affect the optical surface figure accuracy was analyzed.3) The method that controlling the thickness difference of LSCGL in the grinding progress and optical centering and edging were used to obtain high centering errors of LSCGL. The hole processing technology was focused and a prefabricated hole technology was proposed in the paper. A mew tooling was designed for protect the lens, and minimum defects of the machined hole were obtain through the reasonable matching to the processing parameters.A series of machining experiments were carried out base on the processing method aforementioned repeatedly. The results indicate that the processing method is reasonable, and accuracy of polishing spherical surface is PV= 0.27?@?=632.8nm and, PV decrease to 0.829? and RMS decrease to 0.118?after the hole was machined. The concentricity of between the hole and excircle of the lens is 0.01 mm, and the inner dimensional tolerance is 0.02 mm. Several LSCGL samples were machined through the method introduced this paper that 70% proficiency was achieved.