This paper developed an optical design approach to combine the auto-focusing and image sensing in the 2D inspection
system. The focusing principle here employed the chromatic confocal microscopy due to the one-shot focusing capability.
The system held a special issue that the chromatic confocal microscopy has the higher optical dispersion characteristic
than the 2D image sensor which captures a clear image for the optical inspection. Hence, the system here must be
designed to be characterized with both the higher and lower optical dispersion, which was called as the common path
optical design in this study. That is, an optical approach must be developed to divide and switch the above totally
different dispersion conditions. Accordingly, the higher dispersion device, the chromatic confocal sensor, examined the
object surface height to vertically vary the focused position of the 2D inspection system. Furthermore, the lower
dispersion device, the 2D image sensor, can be adjusted to focus onto the object surface so that a clearly focusing image
can be acquired. The experimental results were also provided to ensure this approach can automatically focus the object
surface and then the clear image can be captured to perform optical inspection to obtain the position, dimension or area.
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.
Recently, the industrial optical inspection has been a mainstream in measuring 2D images or 3D profiles of
microstructures. For the 3D profiling, the scanning white-light interferometer has a high resolution, but due to the
broadband light source, it has the low coherence length. Thus, it is very difficult to obtain the focused image with clear
interfered fringes, and the traditional auto-focusing approaches usually determine the wrong focused position. This paper
proposed a useful approach by the passive auto-focusing to determine the accurate focus for the scanning white-light
interferometers. Some experimental results are presented to verify the feasibility of the proposed approach.
3-D profilometry, it is necessary to locate the in-focus region of the image and to reconstruct the best 3D
profile. A series of images are collected on-the-fly. The contrast and the intensity indices of each region of
each image are calculated in the scanning procedure. The proposed method will reconstruct 3D shape from
moving platform. The proposed method is applied on some preliminary experiments and it shows that the
large-scale 3-D profile reconstruction can be realized.
This study employed white-light interferometry to measure the three-dimensional (3D) profiles, roughness, and
dimensions of brightness-enhanced films (BEFs) that exhibited roof-shaped profiles with large-bevel inclines that could
not be successfully measured by conventional optical inspection. A scanning white-light interferometer (SWLI) was used
to obtain image information from both the symmetrical sides of inclines in the BEFs. A feasible structure with an angle-tuning
mechanism was also introduced to enable the scanning white-light interferometer to rotate the angle of vision
according to the bevel angle of the incline in the BEF. Further, the profiles of the BEFs could be reconstructed
successfully through a series of image processing techniques. Now, the allowable bevel angle of the inclines in the BEF
is not greater than 45°. The experimental results confirmed that this approach can successfully measure the 3D profiles
of large-bevel inclines of microstructures as well as the roughness and dimensions of BEFs.