Method for manufacturing lens

Abstract

Method of manufacturing a concave meniscus lens with good surface precision. The method of manufacturing a concave meniscus lens method comprises press molding a glass material in a heat-softened state with a pressing mold. The heated glass material is fed between the molding surfaces of the preheated upper and lower pressing molds and press molded, and the upper and lower pressing molds are cooled to obtain a temporary lens; and when an irregularity is produced on one of the surfaces of the temporary lens, the temperature of the glass material, the preheating temperature of the upper and / or lower molds, or the cooling rate of the upper and / or lower molds is corrected to obtain a corrected lens. When the press molding of the temporary lens is conducted by the first and second pressure applications and an irregularity is produced on one of the surfaces of the temporary lens, the load of the second pressure application is corrected to obtain a corrected lens. The correction is repeated until the irregularity of the corrected lens obtained falls within the permitted range.

Description

technical field [0001] The present invention relates to a manufacturing method of precision press processing for obtaining high-precision glass optical elements without subsequent processing such as grinding and polishing, and is particularly suitable for forming a meniscus lens. Background technique [0002] In the field of precision pressure processing to which the present invention belongs, the glass raw material in a heated and softened state is pressure-formed by using a forming mold that is precisely mirror-processed into a predetermined shape, and the molding surface of the mold is transferred to the glass raw material, thereby forming a product with a predetermined shape. Optical components with surface precision. However, in the glass raw material to which the shape of the forming surface is transferred by press forming, in the subsequent cooling process until demoulding, due to volume shrinkage, physical force received during pressurization, and remaining due to co...

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Problems solved by technology

[0009] However, in the case of press forming a concave meniscus lens, if the pressure is only applied again during the cooling process as in Patent Document 1, a lens with good surface precision cannot be obtained in many cases.

In addition, when the forming die is processed under the condition of forming distortion, it is undesirable to process the forming die into a shape that cancels the distortion, resulting in increased man-hours, increased cost, and reduced productivity.

[0010] The deterioration of the surface accuracy of the glass lens when the precision press forming method is used is caused by deformation during cooling after press working, which is also known in the above-mentioned prior art

However, in the case of concave meniscus lenses, it is not known at all how to control the deformation of the glass from press forming to mold release in order to press form a lens with good surface accuracy.

For example, if figure 1 As shown in , the radius of curvature of the formed lens (tentative lens shape) may change in the radial direction relative to the design value (design shape) of the lens, resulting in distortion, so that the desired surface accuracy cannot be obtained

To sum up, it is impossible to obtain a concave meniscus lens with good surface precision only with the solutions of the prior art

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