In general, Fourier transform infrared (FTIR) spectroscopy works by passing infrared radiation through a sample and measure the output spectrum result. The FFT analysis of the spectrum reveals accurately the identities of the different materials in the sample and also their relative concentration. Hence FTIR is a common tool used in chemical analysis. Conventional FTIR require a mirror-scanning mechanism which makes machines complex, bulky and expensive. Thus, there is always a motivation to fabricate a smaller and lighter spectrometer with relatively good performance and at a low cost. A micro lamellar grating Fourier transform infrared spectroscopy (FTIR) which has been designed in-house and fabricated using surface micromachining process (MUMPS) seems to have offered the solution.
Fig. 1 A platform containing the upper electrode is propped up by hinges designed on the four sides. See figure 1(a,c). The height of the platform from the wafer substrate is about 120um. See figure 1(b). From the top view of the platform, the uppermost electrode is connected to the platform via 8 springs. See figure 1 (a) Also there are lamellar gratings designs on the two sides of the electrode. See figure 1 (d)
Fig. 2 Graph of Intensity of the light beam, I(d) against displacement , d ( λ is the wavelength of the light source.)
Fig. 3. Schematic diagram and actual photograph of the optical setup. Two laser sources are directed onto the gratings of the device. The diffraction pattern is reflected from the beam splitter and the aperture is positioned in such a way that only the zeroth order diffraction beam will reach the laser detector
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