Abstract
Since poor three-dimensional (3D) surface profile (SP) and roughness of components might degrade a system performance, precise determination of the 3D SP of optical surfaces and nano/micro- structures are essential to optimize the manufacturing process. Since high resolution height measurement, shorter processing time, and whole-field measuring capability can be obtained from both confocal microscope (CM) and white-light scanning interferometer (WLSI), they have been widely utilized to determine the 3D SP. In the past, CM was used to measure the 3D SP of a micro specimen with highly rough surface which cannot be measured by a monochromatic interferometer. On the other hand, WLSI was employed to measure the 3D SP of smooth surfaces and/or surfaces of uniform reflectance. In this dissertation, both CM and WLSI were integrated into a self-assembled optical measurement system named as multi-wavelength confocal interference microscope system (MWCIMS). In contrast to the conventional applications of the CM and WLSI, the MWCIMS can be utilized for all-in-focus image (AIFI) and 3D SP measurement of various surface conditions. The self-assembled MWCIMS is consisted of three optical modules: collimated light module, CM module, and Linnik interferometer module. Shape from focus method was implemented in the CM module for measuring AIFI and 3D SP simultaneously. After careful evaluation with eight different surface conditions, energy of Laplacian was found to be the optimal image filter. To record the depth information and gray levels of focus images, the scanning increment per step (SIPS) performed by a translational stage is shorter than the depth of field of the objective lens of the MWCIMS. Phase shifting algorithms (PSAs) were utilized to reconstruct the 3D SP in the Linnik interferometer module. It was found that the performance of the eleven-step PSA is more robust than the traditional PSAs on the reconstruction of 3D SP. Moreover, the calibration of SIPS of a piezoelectric transducer is also proposed to determine the best distance of a single SIP. In addition, the center wavelength of the self-assembled WLSI module can also be determined simultaneously. Excellent noise immunity and measurement results of AIFI and 3D SP with different surface conditions were obtained from both simulation and experimental results of the MWCIMS. The advantages of the self-assembled MWCIMS are lower cost, compact size, and high spatial resolution. Great potential applications are expected in the efficient measurement of various kinds of AIFI and 3D SP in the display and semiconductor industries.