Flexible and Rapid Measurement

Only what you can measure, you can produce. This often quoted statement aptly describes the area of aspheric lenses production in its interplay of progress in fabrication technology and metrology. Nowadays not only the pure feasibility is in focus, but also economical factors: higher flexibility, high measurement speed and high lateral resolution, ideally all combined with a low measurement uncertainty. In this context, we discuss the recently proposed tilted wave interferometer (TWI, Fig. 1), an approach to interferometrically measure steep aspheres and freeforms within a few seconds.