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Proceedings Paper

Low-cost microspectrometer
Author(s): Gerhard Lammel; Sandra Schweizer; Philippe Renaud
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Paper Abstract

We present a tunable interference filter for IR and visible light that scans the desired part of the optical spectrum within milliseconds. A single pixel detector measures serially the intensity at selected wavelengths. This concept avoids expensive linear detectors as used for grating spectrometers. The tunable optical interference filter is fabricated by a new porous silicon batch technology using only tow photolithography steps. The refractive index of this filter microplate is gradually modulated in depth to create a Bragg mirror or a Fabry-Perot bandpass filter for a transmission wavelength between 400 nm and 6 micrometers . Two thermal bimorph micro-actuators tilt the plate by up to 90 degrees, changing the incidence angle of the beam to be analyzed. This tunes the wavelength transmitted to be detected by a factor of 1.5, e.g. form 4 micrometers to 6 micrometers . The filter area can be chosen between 0.27 mm by 0.70 mm and 2.50 mm by 3.00 mm, its thickness is typically 30 micrometers . The spectral finesse of 25 is sufficient for most diagnosis applications, e.g. detection of CO2 and CO in combustion processes by their IR absorption bands. Online colorimetery and color correction of desktop printers can be envisaged.

Paper Details

Date Published: 22 August 2000
PDF: 8 pages
Proc. SPIE 4178, MOEMS and Miniaturized Systems, (22 August 2000); doi: 10.1117/12.396515
Show Author Affiliations
Gerhard Lammel, Swiss Federal Institute of Technology Lausanne (Germany)
Sandra Schweizer, Swiss Federal Institute of Technology Lausanne (United States)
Philippe Renaud, Swiss Federal Institute of Technology Lausanne (Canada)

Published in SPIE Proceedings Vol. 4178:
MOEMS and Miniaturized Systems
M. Edward Motamedi; Rolf Goering, Editor(s)

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