Setup and Application of two-beam reflection method for measurement of curvature change

• Main Authors: Yue-Ting Lin, 林岳廷
• Other Authors: Wei Pan
• Format: Others
• Language: en_US
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/74131639432434658458

碩士 === 國立中正大學 === 物理所 === 98 === In our research, a two-beams reflection system composed of PSD (Position Sensitive Detector), OPS (Optical Position Sensor), diode laser, AD734 divider, and PZT (piezomechanics), is setup and applied to measure the tiny curvature change of the object by heating process or the resonance of the object by providing a sound source. This system can be applied to measure the thermal expansion coefficient by increasing or decreasing the temperature within 0.5~3 degrees. In the first experiment, we measured the ΔV from PSD (Position sensitive detector) in heating process and transformed ΔV into curvature change Δ (1/R) by labview program, obtained the ratio of curvature change Δ (1/R) and ΔT of each material and calculated the thermal expansion coefficient by regarding one of them as a standard point. The accuracy of the coefficient can be reached to 3%~5%. Furthermore we can measure the thermal expansion coefficient of unknown objects. In the second experiment, we provided a sound source and found the resonance frequency of different rectangular plate in different length by observing the tiny vibration on the plate surface. We observed the suddenly change of amplitude ΔV from the PSD in specific frequency, speculated it is the resonance phenomenon, and conjectured the frequency we provided is the nature frequency of the sample. On the other hand, the theoretical nature frequency can be obtain by solving the wave equation of rectangular plate in different boundary conditions, we compared the frequency we measured to the theoretical value to make sure the frequency is resonance frequency. Furthermore we can measure the resonance frequency of irregular shape objects. According to these experiments, we confirm our system can be applied to the microscopic surface measurement.