Micro-Electro-Mechanical Systems (MEMS) or Micro-Opto-Electro-Mechanical Systems (MOEMS) integrate mechanical (or/and opto) elements, sensors, actuators, and electronics on a common silicon substrate through micro-fabrication technology. MEMS promise to revolutionize nearly every product category by bringing together silicon-based microelectronics with micromachining technology, making possible the realization of complete systems-on-a-chip. MEMS devices are manufactured using batch fabrication techniques similar to those used for integrated circuits and quality control is a key to making a successful product. Currently, approximately 80% of the total cost of MEMS comes from final packaging and test; successful products will require rapid, accurate metrology of the devices to improve yields and profitability of the devices. At present, interferometric optical profilers are widely used to measure surface features of unpackaged MEMS due to their high speed, accuracy, and flexibility. With the further productization of MEMS technology, the devices need to be tested in their final packaged state, typically underneath a protective surface such as glass, plastic, or sapphire. Low-magnification objectives capable of imaging through dispersive media have been available for several years. Increasingly, though devices require high-magnifications in order to resolve key features. With high magnification, however, transmissive media can greatly degrade the interferometric measurement due to dispersion and aberration effects. In addition, long working distance optics are required to accommodate the distance between the protective layer and MEMS device. In this paper, improved techniques are described to measure surfaces underneath transmissive materials at higher magnifications. Many factors must be optimized, including dispersive compensation, coherence effects, thickness variation insensitivity, and illumination. Measurement results will be presented for a standard objective and a dispersion-compensated objective. Error minimization and comparison of measurements with and without protective layers will also be discussed.

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A method to measure spectrum with different in refractive index based on white-light interferometry is described. Nanourchins were detected under various environmental index liquid of glycerin solution. The system with a spectral centroid algorithm shows a detection capability of index change 7.15 mRIU.

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Abstract — We demonstrate an effective technique which allows one to characterize a small radius micro-ring resonator via low coherence interferometric measurement beyond light source bandwidth limitation. The experimental results show significant improvements in the extracted parameters.

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A self-aligned dual hole-patterned electrode liquid crystal (LC) lens with electrically positive and negative variable focuses is demonstrated. The device combine by the glass with dual hole-patterned electrodes on both surfaces, a ngative type LC layer with vertical alignment (VA) and a positive type LC layer with homogeneous alignment as a sandwich structure.

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A novel heterodyne Wollaston interferometer is presented for in-plane displacement measurement. The proposed interferometer combines the advantages of heterodyne interferometry, grating interferometry, Wollaston interferometer, and common-optical-path technique. Experimental results demonstrate that the measurement resolution and range can achieve to 2 nm and 50 mm.

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