Researcher:
Torun, Hamdi

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Master Student

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Hamdi

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Torun

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Torun, Hamdi

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2006 - 200932010 - 20121

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Researcher Of Publications: search.filters.isAuthorOfPublication.9e5c95cc-0b92-40d9-922f-6d3affb5f2c1

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    Uncooled thermo-mechanical detector array with optical readout
    (Walter De Gruyter Gmbh, 2006) N/A; N/A; Department of Electrical and Electronics Engineering; Department of Electrical and Electronics Engineering; Torun, Hamdi; Ürey, Hakan; Master Student; Faculty Member; Graduate School of Sciences and Engineering; College of Engineering; N/A; 8579
    This paper reports a novel uncooled infrared FPA whose performance is comparable to the cooled FPA's in terms of noise parameters. FPA consists of bimaterial microcantilever structures that are designed to convert IR radiation energy into mechanical energy. Induced deflection by mechanical energy is detected by means of optical methods that measure sub nanometer thermally induced deflections. Analytical solutions are developed for calculating the figure of merits for the FPA. FEM simulations and the analytical solution agree well. Calculations show that for an FPA, NETD of < 5 mK is achievable in the 8-12 pm band. The design and optimization for the detectors are presented. The mechanical structure of pixels is designed such that it can be possible to form large array size FPA's. Microfabrication of the devices to improve the performance further; employs low cost standard MEMS processes.
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    Thermo-mechanical detector array with optical readout
    (IEEE-Inst Electrical Electronics Engineers Inc, 2006) N/A; N/A; Department of Electrical and Electronics Engineering; Department of Electrical and Electronics Engineering; Torun, Hamdi; Ferhanoğlu, Onur; Ürey, Hakan; Master Student; PhD Student; Faculty Member; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; 205198; 8579
    An uncooled thermal detector array with low NETD is designed and fabricated using MEMS bimaterial structures that bend in response to thermal change. A diffraction grating placed underneath each pixel allows sensing sub-nm mechanical deflections.
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    PublicationOpen Access
    Thermal deflections in multilayer microstructures and athermalization
    (American Institute of Physics (AIP) Publishing, 2006) Department of Electrical and Electronics Engineering; Department of Electrical and Electronics Engineering; Torun, Hamdi; Ürey, Hakan; Faculty Member; College of Engineering; N/A; 8579
    Exact and approximate analytical solutions are developed for calculating the thermally induced deformation of three-layer cantilever structures. The solution is derived from the closed-form solutions for multilayer films. Thermal deformation and athermalization conditions are derived using dimensionless parameters for film to substrate thickness ratios for three-layer structures. The analytical solution for a narrow beam is applied to a scan mirror plate suspended with two torsional flexures. The results agreed well with finite element method simulations and experiments. Tests are performed using a bulk-micromachined silicon microelectromechanical system scanner that has a thin gold (Au) coil layer on one side and an aluminum (Al) mirror layer on the other side. Useful figures using film-to-substrate thickness ratios and the material independent normalized parameters are introduced for easy thermal deformation computations and performance trades for three-layer structures.
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    PublicationOpen Access
    Diffraction grating based optical readout for thermal imaging
    (Society of Photo-optical Instrumentation Engineers (SPIE), 2012) Department of Electrical and Electronics Engineering; Department of Electrical and Electronics Engineering; Adiyan, Ulaş; Erarslan, Refik Burak; Torun, Hamdi; Ferhanoğlu, Onur; Ürey, Hakan; PhD Student; Faculty Member; College of Engineering; N/A; N/A; N/A; N/A; 8579
    The thermal sensor system presented in this paper is based on the mechanical bending due to the incident IR radiation. A diffraction grating is embedded under each pixel to facilitate optical readout. Typically the first diffraction order is used to monitor the sub-micron mechanical displacement with sub-nanometer precision. In this work; two different optical readout systems based on diffraction gratings are analyzed. First setup employs a conventional 4f optical system. In this one-to-one imaging system, collimated light is propagated through a lens, filtered with an aperture and then imaged onto a CCD by a second lens. Second system is more compact to improve image quality and to reduce noise. This is achieved by using an off-axis converging laser beam illumination that forms the Fourier plane near the imaging lens. This approach has important advantages such as reducing number of optical components and minimizing the optical path. The system was optimized considering parameters such as laser converging angle, laser beam size at MEMS chip, and magnification of the imaging system.