Design of a hyperspectral sensor in a MEMS technology

Problem Definition:

Infrared imaging is extensively used in industrial and medical applications, for example: thermography, night-vision, body temperature sensing for medical uses… Additionally, a lot of molecules absorb infrared wavelengths, which makes the detection of lots of chemical compounds possible by making use of their absorption spectrum. This has its applications in medical diagnosis and food quality control, for example.

In order to measure the spectrum of an infrared source, a Michelson interferometer could be used. In this setup, the light interferes with a delayed version which together generates an interference pattern. To introduce this delay, a movable mirror is used which generates displacements of tens of micrometers with an accuracy of tens of nanometers. From this interferogram, the spectrum can then be calculated using a fourier transform. In order to generate these small displacements with high accuracy, a MEMS-based solution seems very attractive. 


Example of a MEMS-based Michelson inferferometer[1]

[1] Saadany, B.; Omran, H.; Medhat, M.; Marty, F.; Khalil, D.; Bourouina, T., "MEMS tunable Michelson interferometer with robust beam splitting architecture," Optical MEMS and Nanophotonics, 2009 IEEE/LEOS International Conference on , vol., no., pp.49,50, 17-20 Aug. 2009


Objectives:

The goal of this thesis is to design a very compact movable MEMS micromirror in a commercially available MEMS technology. The MEMS processes that will be used are the MUMPs processes (Muli-User MEMS Processes) offered by MEMSCAP, which are available at the CMST laboratory. Based on a literature study, a specific embodiment of such a movable MEMS mirror will be chosen, taking into account the specifications of the above-mentioned interferometer. Then, the complete design of the micromirror will be carried out in the MUMPs technology. All necessary software for making the layout and for simulating the micromirror (electrical + mechanical + optical) is available at the CMST laboratory. Additionally, some peripheral electronics will need to be designed to drive this micromirror. Once the design is finished, the micromirror will be fabricated using the MUMPs technology of MEMSCAP.


Keywords:

MEMS technology, optics, interferometer, mechanical design, CAD

Location:

Ardoyen CMST + at home.