Brief description of the project:
The characterization of lenses used in ophthalmology places increasing demands on measurement technology. The aim of this project is to develop a wavefront sensor with a large dynamic range based on current MEMS technology that meets these increased requirements.
Wavefront sensors can be used for detailed characterization of optics. Both imaging optics can be measured, as well as optics that cannot generate an optical image individually, but are intended for use in a lens system. The most common type of wavefront sensors are Shack-Hartmann sensors. In a highly simplified form, a Shack-Hartmann sensor consists of a flat matrix of many microlenses that focus the incident light on a CCD or CMOS sensor and generate a characteristic dot pattern. The wavefront can be reconstructed from the dot pattern and compared with the theoretical design of the optics.
Shack-Hartmann sensors are subject to restrictions with regard to lateral resolution and dynamics, so that strong gradients and curvatures of a wavefront can only be detected up to a certain limit. Although the dynamic range of current Shack-Hartmann sensors already covers wavefronts with several hundred to thousand lambda shape heights, an extension of the dynamic range would be interesting for extreme specimens. Especially for the characterization of complex ophthalmic lenses an increase of the lateral resolution would be advantageous in some cases. In order to avoid this limitation, TRIOPTICS is developing a new wavefront sensor based on MEMS mirrors with which the wavefront is scanned laterally with high resolution with funding from the European Fund for Regional Development (ERFE). This eliminates the need for a rigid lens matrix and the associated physical limits of the Shack-Hartmann sensor. A special detection concept is designed to additionally increase the dynamic range while maintaining the same accuracy.