Non-Scanning Non-Interferometric Intensity-Type Three-Dimensional Optical Profilometers and Microscopes

• Main Authors: Chen-Tai Tan, 譚振台
• Other Authors: Ming-Hung Chiu
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/52uq5d

博士 === 國立虎尾科技大學 === 光電與材料科技研究所 === 100 === The essence of study is based on the reflectivity-to-height transformation and using the CCD imaging technique to build up a new three-dimensional profilometer or microscope. According to the basic geometrical optics, the test ray angle on the test surface is proportional to the slope of the surface. The deviation angle from the optics axis is also proportional to the slope and inversely proportional to the magnification of optical system. We used the confocal configuration to build up the optical system and to magnify the image of the specimen. The output ray angles are sensed based on the critical angle method. Because of its high angular resolution, the intensity pattern is sensitive to the surface profile. Comparing with the intensity pattern of total-internal reflection, the reflectivity profiles are obtained. As mentioned above, we should use a CCD sensor to be located at the image plane and to record either the critical angle image or the TIR image in real time. Overlapping these two images is well. The reflectivity profile can be transformed into the surface profile immediately. From the Fresnel’s equations, although the sensitive of height in the p-polarization light in twice internal reflection is more than that of in the s-polarization light, the image quality of the s-polarization light is better and the dynamic range of height is larger. In this paper, a series of studies on the 3-D profilometer and microscope are presented. The optical configurations contain the reflection and transmission types and the magnification is increased from 10 to 1250 times, where the specimens including any kind of transparent and opaque objects are measurable. The 3-D profile plotting is like as taking a shot without scanning. The advantages of this method are non-destructive, non-contact, and non interferometric, so it does’nt need a complicated phase analysis. In addition, it has other merits, such as, easy assembly, easy operation, large area testing, and real time 3-D measurements.