Novel technique for measurement of centration errors of complex completely mounted multi-element objective lenses

Abstract

The size and the focal length of camera objectives (e.g. cell phones or digital cameras) are becoming smaller and smaller. At the same time the quality requirements are increasing. Besides surface accuracy, the imaging quality of the complete optics is mainly influenced by the alignment errors of the single elements. TRIOPTICS has developed a new technology called MultiLens in order to measure the centering errors of all single surfaces within an objective lens with up to 40 surfaces or more. We achieve accuracies in the range of an arc second. During the measurement the deviation of each center or curvature with respect to a reference axis is measured. These data are further processed in order to provide the shift and tilt of an individual lens or group of lenses in respect to a given reference axis (Patent pending Ref. 1). Applications mainly include the measurement of cell phone and digital camera lenses. However, any type of objective lens from endoscope up to very complex objective lenses used in microlithography can be measured with highest accuracy. The method has been extended to measure also the aspherical axis of lenses.