| Summary: | 碩士 === 國立虎尾科技大學 === 光電與材料科技研究所 === 100 === In this study, we proposes a non-scanning, non-interferometric, three- dimensional (3D) optical microscope based on geometric optics, and critical angle principle. According to the first-order optic approximation, the deflection angle of the reflection light from the test specimen is proportional to its surface height.
In addition, the reflectance of a parallelogram prism is also proportional to the incident angle at the critical angle nearby. We used two charge-coupled devices (CCD) as cameras to record the images at the critical angle nearby and at the angle of total internal reflection, respectively, for making a reflectance profile. The reflectance profile can be transformed into the 3-D surface profile of the test surface.
Because the reflectance curve versus the incident angle is nonlinear, the nonlinear-error compensation is need to do in order to reduce the error and to enhance the measurement accuracy. This is one of the focus in this study.
The reflectance profile, obtained from CCDs, is the ratio of intensity recorded at the critical angle to the intensity recorded at the total internal reflection angle. The 3-D microscope provides a sub-micron measuring range with nanometer resolution in the axial direction and can also be used to measure roughness, film thickness or surface defects in real time.
|
|---|
