A micro-fabricated optical scanner for rapid non-contact thickness measurement of transparent films

作者：Mansoor H^*; Zeng H; Chiao M

来源：Sensors and Actuators A: Physical , 2011, 167(1): 91-96.

DOI：10.1016/j.sna.2011.02.020

• Microelectromechanical systems
• Film thickness measurement
• Confocal scanner
• Magnetic actuation

In this work a fiber optic scanner for non-contact thickness measurement of transparent and semi-transparent films is presented. Thickness measurement is performed by scanning the focal point of a microlens across the thickness of a film and logging the intensity signal of the single scattering light reflected back from the sample. When the focal point of the scanning microlens passes the surface boundaries of the sample, intensity peaks are detected in the reflecting signal. Thickness is calculated using the index of refraction of the sample and the displacement of the lens between intensity peaks. The measurement is performed in a fraction of a second to eliminate signal artifacts that are due to the external vibrations. A magnetically driven micro-fabricated actuator is developed for actuating the microlens. Scanning range of 204 mu m at resonant frequency of 544 Hz is achieved when an AC magnetic field of 14 mT is applied. To evaluate the scanner, thickness of SU-8 negative photoresist layers deposited on silicon wafers was measured.

• 出版日期2011-5