The in-situ measurements for continuously rolling optical films by the chromatic confocal apparatus have been
successfully achieved by the authors. The apparatus presented here consists of chromatic confocal to avoid the vibrations
caused by the roller machine while working. Without the need of the vertical z axis scan, chromatic confocal can give
instant thickness measurements. Therefore, the apparatus possesses the characters of high resolution and fast response.
We believe that this system can highly monitor and improve the yield rate in production lines.
In this paper, a method integrating image processing and signal frequency is used to estimate relative misalignment of
micro-structure the Double-sided Lenticular Lens Films (LLF). The pitch of the convex on each side of the LLF is
900μm. The main steps of this research consist of image denoising, edge detection and establishment of the
misalignment v.s. image magnitude relation. A Butterworth low-pass filter is used to eliminate the noise due to debrits
on the polymer substrate. The images that are acquired from LLFs for different relative misalignment quantities are used
to analyze the spectrum and get its relation between misalignment position and frequency energy distribution. The
experiment shows the proposed method may distinguish between cases with different relative misalignment of microstructure
on LLF with a resolution of 20μm.
We develop a novel target, dual-overlay grating, used in the overlay measurement with an optical bright-field
imaging tool. The dual-overlay grating is the combination of two overlay gratings with different pitch. The two
overlay grating are approached each other and the separation gap between them is sub-micrometer. The image in the
proximity of the boundary of two overlay gratings is measured at in-focus position, and a method is built to analyze
the image. The gradient value of image and a merit value are calculated. A series of dual-overlay grating is measured
and analyzed with different overlay offset. We found the relation between the merit value and overlay offset is linear
in certain region, and the dual-overlay grating has the nano-scale resolution to the overlay offset. Thus, the
dual-overlay grating has potential application in overlay metrology for the process control in the future semi-conductor manufacturing.