| 1. |
- Aad, G., et al.
(författare)
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- 2012
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swepub:Mat__t (refereegranskat)
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| 2. |
- Aad, G., et al.
(författare)
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- 2011
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swepub:Mat__t (refereegranskat)
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| 3. |
- Aad, G., et al.
(författare)
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- 2012
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swepub:Mat__t (refereegranskat)
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| 4. |
- Ayerden, N.P., et al.
(författare)
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A miniaturized optical gas-composition sensor with integrated sample chamber
- 2016
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Ingår i: Sensors and Actuators, B: Chemical. - : Elsevier BV. - 0925-4005. ; 236:29, s. 917-925
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Tidskriftsartikel (refereegranskat)abstract
- A robust and highly miniaturized optical gas sensor based on optical absorption spectroscopy is presented. By using the resonator cavity of a linear variable optical filter (LVOF) also as a gas chamber, a compact and robust optical sensor is achieved. The device operates at the 15th order in 3.2–3.4 μm wavelength range for distinguishing hydrocarbons. The physical cavity length at the μm-level is translated into an effective optical absorption path length at the mm-level by the use of highly reflective (R > 98%) Bragg mirrors. The optical design using the Fizeau interferometer approach is described. Moreover, the CMOS-compatible fabrication method is explained. In addition to the wideband and single wavelength filter characterization, absorption of methane in the LVOF cavity is demonstrated at 3392 nm and 3416.60 nm wavelengths.
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| 5. |
- Emadi, Arvin, et al.
(författare)
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Spectral measurement using IC-compatible linear variable optical filter
- 2010
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Ingår i: Proc. of SPIE. - : SPIE. ; 7716
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Konferensbidrag (refereegranskat)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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| 6. |
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| 7. |
- Ghaderi, Mohammadamir, 1986, et al.
(författare)
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Thermal annealing of thin PECVD silicon-oxide films for airgap-based optical filters
- 2016
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Ingår i: Journal of Micromechanics and Microengineering. - : IOP Publishing. - 1361-6439 .- 0960-1317. ; 26:8
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Tidskriftsartikel (refereegranskat)abstract
- This paper investigates the mechanical and optical properties of thin PECVD silicon-oxide layers for optical applications. The different deposition parameters in PECVD provide a promising tool to manipulate and control the film structure. Membranes for use in optical filters typically are of ∼λ/4n thickness and should be slightly tensile for remaining flat, thus avoiding scattering. The effect of the thermal budget of the process on the mechanical characteristics of the deposited films was studied. Films with compressive stress ranging from -100 to 0 MPa were deposited. Multiple thermal annealing cycles were applied to wafers and the in situ residual stress and ex situ optical properties were measured. The residual stress in the films was found to be highly temperature dependent. Annealing during the subsequent process steps results in tensile stress from 100 to 300 MPa in sub-micron thick PECVD silicon-oxide films. However, sub-100 nm thick PECVD silicon-oxide layers exhibit a lower dependence on the thermal annealing cycles, resulting in lower stress variations in films after the annealing. It is also shown that the coefficient of thermal expansion, hence the residual stress in layers, varies with the thickness. Finally, several free-standing membranes were fabricated and the results are compared.
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| 8. |
- Middelburg, Luke, et al.
(författare)
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Combining impedance spectroscopy with optical absorption spectroscopy in the UV for biofuel composition measurement
- 2017
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Ingår i: I2MTC 2017 - 2017 IEEE International Instrumentation and Measurement Technology Conference, Proceedings. - 9781509035960
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Konferensbidrag (refereegranskat)abstract
- A capacitive probe is generally used in a flex-fuel engine for measuring the ethanol content in biofuel. However, the water content in biofuel of high ethanol content cannot be disregarded or considered constant and the full composition measurement of ethanol, gasoline and water in biofuel is required. Electrical impedance spectroscopy with a customized capacitive probe operating in the 10 kHz to 1 MHz frequency range is combined with optical absorption spectroscopy in the UV spectral range between 230 and 300 nm for a full composition measurement. This approach is experimentally validated using actual fuels and the results demonstrate that electrical impedance spectroscopy when supplemented with optical impedance spectroscopy can be used to fully determine the composition of the biofuel and applied for a more effective engine management. A concept for a low-cost combined measurement system in the fuel line is presented.
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| 9. |
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| 10. |
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