Optics for digital photography
 

Computer-aided development of optical components

In the mathematical office of Schneider-Kreuznach, design specialists develop the optical system using high-performance computers and special software. The developers can fall back on the experience from many thousands of optical components. While in the early days optical calculations were carried out using logarithmic tables (and later the legendary computers developed by Konrad Zuse), today advanced CAD systems enable calculation, simulation and testing of highly complex structures within a much shorter time.

Once development work has been completed, the Schneider engineers use computer-aided software for designing the complete lens and specify the geometric requirements for the perfect interaction of lens and fitting. The quality of the optical calculation must be converted with absolute mechanical precision, because high-quality elements must be positioned exactly in the lens.

The fittings for Schneider lens systems are produced in advanced CNC-production facilities from aluminium and brass. Schneider-Kreuznach focuses on lightweight and simultaneously robust design in order to guarantee maximum user convenience and reliability. Computer-controlled processing steps such as turning, milling and drilling are followed by elaborate finishing of the fitting surface, including inscription.
 

Schneider-Kreuznach also uses high-precision, computer-controlled manufacturing technologies for the lens production to achieve optimum precision and reproducibility. Many of the 130 different types of glass have to be processed particularly carefully. The sophisticated lenses are ground, polished, centred and coated in several manufacturing steps.

 

Production of these lens types, which are essential in many advanced lens systems, is particularly demanding: aspheric lens elements deviate from the traditional spherical surface shape. In addition to significantly increased reproduction performance, they also enable construction of very compact lens systems. Both characteristics are essential, particularly for application in digital compact cameras. Schneider-Kreuznach specialises in the production of aspheric surfaces, using the particularly efficient MRF technique (magnetorheological finishing).
 

The final step in the manufacturing process for an optical lens is coating: Antireflection coating protects the sensitive special glass from chemical and physical influences and improves the contrast rendering. In digital cameras, high-quality coating leads to noise reduction. The advanced  multi-coating process involves application of several transparent metal oxide layers in high vacuum-equipment under clean room conditions at the Schneider-Kreuznach coating centre. To this end, the glasses are places in special calottes.

As one of the leading manufacturers of high-precision optical systems worldwide, a crucial requirement for Schneider-Kreuznach is that only first-class products should leave the company. For this reason, each finished lens is subjected to a three-stage test procedure.

3D precision measurement is based on computer-controlled instruments for measuring the accuracy of the mechanical components. The optical engineers then use MTF measurements to check for deviations between the actual optical system and the calculation. At the end of the control chain is the visual examination of each lens by Schneider experts, focussing on optical performance as part of projection test as well as cosmetic aspects (dust, scratches). The product only leaves the plant as high-performance lens 'Made in Bad Kreuznach' once it has successfully passed this check – en route to the best photographers in the world.