05/08/2018

Topography measurement on optical lenses

For process control in the manufacturing of plastic lenses, the topography of strongly curved lenses with high resolution is to be measured and the radius of curvature determined.

Conventional stylus instruments cannot be used for this measurement task because they do not detect the bottom of the lens surface. Probes that mechanically scan the surface are also unsuitable for optical components in particular, as they scratch them. Contactless optical probes such as autofocus sensors or triangulators either have too small measuring ranges or the required resolution is not achieved.

The MicroProf® offers the solution with a confocal, chromatic distance sensor. The sensor focuses white light on the target and determines the height of the target in the measuring spot from the spectral distribution of the light scattered on the surface. Different measuring heads with measuring ranges up to 10 mm and a height resolution from 3 nm are available for different measuring tasks. The sensor has a large aperture ratio and can directly measure the polished lens surface up to an inclination of 30°. The strong inclination of the lens surface in the edge area of up to 70° can be completely detected with a sprayed on chalk powder. Lens topographies can be easily acquired with the MicroProf®.

In the FRT measuring systems, the powerful Mark III analysis program provides extensive functions for displaying and evaluating the measured data. Mark III enables the user to measure volumes and areas as well as to determine distances or angles. Circles, aspheres and polynomials can be fitted to measured profiles.

We certainly have a solution for your specific task. Do not hesitate to contact us if you have any questions. Our experts will be glad to take care of your needs and work out individual solutions for you.