09/04/2018

Part 2/5: Software Package „Lens Shape“

SERIES Acquire Automation XT – FRT’s Powerful Multi-Sensor Software

Irrespective of large lenses or micro optics, the systems are becoming more complex, with multiple production processes and have already penetrated into the sub-nanometer range.

The new software package “Lens Shape“ for Acquire Automation XT is used for fully automated characterization of the shape properties of lenses. The shape of the sample is recorded by means of star-shaped profile measurements and then analyzed by the fitting of an ideal shape (sphere or polynomial). The profiles are arranged in such a way that their common intersection point lies at the apex of the lens. The user can determine the number and angle alignment of the profiles. With a topography point sensor, e. g. the CWL, the shape of lenses can be determined. It is key factor in the quality and functionality of lenses.

Interested in latest posts of this series? Click below.

Part 1/5: Hybrid metrology for fast and reliable determination of inaccessible parameters

Part 3/5: New „Layer Mode“ for Field of View sensors

Part 4/5: Software package for overlay measurement

In order to ensure that the profile measurements are actually performed over the lens apex, an additional automatic routine can be added which determines the exact position of the apex using two profile measurements in x- and y-direction and if an offset is detected, the following profile measurements are adapted accordingly.

The subsequent evaluation routine “Lens evaluation“ automatically determines the lens shape. An ideal shape is fitted to each of the previously measured profiles and the deviation of the measured data from the ideal shape is determined. The fitted shape can be defined either by a circular function (sphere) or by a polynomial. The fit can be done automatically, whereby the radius of curvature is determined in the case of a circular function and the coefficient of curvature in the case of a polynomial. Alternatively, the shape can also be defined by the user using a fixed radius of curvature or a polynomial function. In this case, the shape is positioned within the scope of the fitting in such a way that the deviation from the measured data is minimal. The evaluation also displays the deviation of the measured shape from the fitted shape. In the measurement report it is possible to display the measured and fitted data as well as the difference between both for each measurement profile.

With our 3D surface measuring systems of the proven MicroProf® series, area measurements as well as single and multiple profiles can be measured without contact. There is the possibility of automated mapping of the samples, as well as automated evaluation routines. Lens roughness can be determined down to the sub-nanometer range and topography measurements of the sample surface can be performed. The MicroProf® tools also offer the option of double-sided sample measurement. This allows simultaneous measurement of the top and bottom surfaces of the sample and thus the determination of the sample thickness. Therefore the total thickness variation (TTV) of the sample together with surface parameters such as roughness and flatness of both surfaces can be determined.

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.

Interested in latest posts of this series? Click below.

Part 1/5: Hybrid metrology for fast and reliable determination of inaccessible parameters

Part 3/5: New „Layer Mode“ for Field of View sensors

Part 4/5: Software package for overlay measurement