Precise processing and molding

SCHOTT manufactures precisely shaped and polished aspherical lenses in small and large quantities

Mainz (Germany), June 29, 2011 – Aspherical lenses can be used to make more compact, lighter and yet better optical systems. SCHOTT relies on two manufacturing techniques to produce these lenses in complex shapes: CNC technology and precision molding. Both techniques offer advantages that can be used in specific products for customers.

Aspherical lenses have a complex shape. This helps to prevent aberrations that are unavoidable with spherical lenses. They are usually produced with the help of multistage CNC grinding processes. To begin with, a lens blank is shaped using grinding processes. Afterwards, it is magnetorheologically polished at SCHOTT up to an accuracy of 0.2 µm PV and finally coated.

Because each blank is processed individually, the lenses are extremely flexible in terms of their design. They can be made of any type of glass, even synthetic quartz glass. The CNC technique is particularly well-suited for manufacturing small to medium-size series with diameters of 12 to 180 mm. In fact, SCHOTT is currently quite active in manufacturing aspheres out of synthetic quartz glass for a variety of different laser applications. “Precision molding, on the other hand, is ideally suited for the cost-effective manufacturing of large series or of small optical components that have complex shapes,” explains Charles Bernheim, Product Manager for Optical Components at SCHOTT Advanced Optics in Mainz. “Here, polished pre-forms made of low TG glass are heated and pressed using a mold having the form of the optical component that should be produced” he adds.

SCHOTT developed the so-called “Low Tg” glasses especially for precision molding. They can be shaped and processed even at a low transformation temperature (Low Tg) by using established machines and molding materials. Due to the higher initial investment necessary for the mold, this process is suited for manufacturing larger quantities.

With precision molding, the typical lens diameter lies between 1.5 and 40 mm. The lens structures can actually be extremely small, yet be formed in a very steep manner. Typical applications of this mass production technique include aspherical lenses for microscopes, cameras or binoculars, but also lens arrays for use in LED lighting.

Highly refractive lenses can be manufactured in arrays and strings with the help of the improved precision molding technique. This photo shows a lens array that is made up of 19 lenses that are each 5 millimeters in diameter. Source: SCHOTT

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SCHOTT is an international technology group with more than 125 years of experience in the areas of specialty glasses and materials and advanced technologies. SCHOTT ranks number one in the world with many of its products. Its core markets are the household appliance, solar power, pharmaceuticals, electronics, optics, transportation and architecture industries. The company is strongly committed to contributing to its customers’ success and making SCHOTT an important part of people’s lives with high-quality products and intelligent solutions. SCHOTT is committed to managing its business in a sustainable manner and supporting its employees, society and the environment. The SCHOTT Group maintains close proximity to its customers with manufacturing and sales units in all major markets. Its workforce of around 17,500 employees generated worldwide sales of approximately 2.9 billion euros for the 2009/2010 fiscal year. SCHOTT AG, with its headquarters in Mainz (Germany) is owned by the Carl Zeiss Foundation.