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- Emadi, Arvin, et al.
(author)
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Spectral measurement using IC-compatible linear variable optical filter
- 2010
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In: Proc. of SPIE. - : SPIE. ; 7716
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Conference paper (peer-reviewed)abstract
- This paper reports on the functional and spectral characterization of a microspectrometer based on a CMOS detectorarray covered by an IC-Compatible Linear Variable Optical Filter (LVOF). The Fabry-Perot LVOF is composed of 15dielectric layers with a tapered middle cavity layer, which has been fabricated in an IC-Compatible process using resistreflow. A pattern of trenches is made in a resist layer by lithography and followed by a reflow step result in a smoothtapered resist layer. The lithography mask with the required pattern is designed by a simple geometrical model and FEMsimulation of reflow process. The topography of the tapered resist layer is transferred into silicon dioxide layer by anoptimized RIE process. The IC-compatible fabrication technique of such a LVOF, makes fabrication directly on aCMOS or CCD detector possible and would allow for high volume production of chip-size micro-spectrometers. TheLVOF is designed to cover the 580 nm to 720 spectral range. The dimensions of the fabricated LVOF are 5×5 mm2. TheLVOF is placed in front of detector chip of a commercial camera to enable characterization. An initial calibration isperformed by projecting monochromatic light in the wavelength range of 580 nm to 720 nm on the LVOF and thecamera. The wavelength of the monochromatic light is swept in 1 nm steps. The Illuminated stripe region on the cameradetector moves as the wavelength is swept. Afterwards, a Neon lamp is used to validate the possibility of spectralmeasurement. The light from a Neon lamp is collimated and projected on the LVOF on the camera chip. After dataacquisition a special algorithm is used to extract the spectrum of the Neon lamp.
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