Digital holographic microscopy for MEMS/MOEMS device inspection and complete characterization
Hegde, G. M.
Singh, Vijay Raj
Date of Issue2013
School of Mechanical and Aerospace Engineering
Digital holography became feasible since the availability of charged coupled devices (CCDs) with smaller pixel sizes, higher pixel numbers and high speed computers. Fresnel or Fourier holograms are recorded directly by the CCD and stored digitally in the computer. The reconstruction of the wavefield, which is done optically by illumination of a hologram in conventional holography, is performed by numerical methods in digital holography. In the numerical reconstruction process, not only the intensity but also the phase distribution of the stored wavefield can be computed from the digital hologram. This offers new possibilities for a variety of applications. This review article describes the principle of digital holographic microscopy (DHM) and its major applications in microelectro-optomechanical systems (MEMS/MEOMS) inspection and characterization. MEMS structures are generally realized using different material layers involving various process steps. Static and dynamic characterization of MEMS devices form an important part in carrying out their functional testing and reliability analyses. Development of a digital holography (DH) based system for micro-device inspection and characterization is presented in this review. A reflection mode hand-held type compact DH microscope system is developed based on the lensless magnification configuration. Application of the developed system is demonstrated for MEMS structures such as cantilever, diaphragms, accelerometer, microheater inspection. Further, both static and dynamic characterizations of these MEMS structures are illustrated.
Journal of the Indian institute of science
© 2013 Indian Institute of Science. This paper was published in Journal of the Indian Institute of Science and is made available as an electronic reprint (preprint) with permission of Indian Institute of Science. The paper can be found at the following URL: [http://journal.library.iisc.ernet.in/index.php/iisc/article/view/1110/1339]. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper is prohibited and is subject to penalties under law.