We present a miniaturized Fourier transform spectrometer (FTS) based on optical microelectromechanical system technology. The FTS is a Michelson interferometer with one scanning mirror. A new type of electrostatic comb drive actuator moves the mirror. We have measured a nonlinearity of the driving system of 60.5 mm for a displacement of 38.5 mm. A method is presented to correct the spectrum to get rid of the nonlinearity. The driving reproducibility is 625 nm. The measured resolution of the spectrometer after the phase correction is 6 nm at a wavelength of 633 nm.Fourier transform (FT) spectroscopy is a well-known technique to measure the spectra of weak extended sources. It offers distinct throughput and multiplex advantages, which provide higher signal-to-noise ratio performance than other methods. However, commonly used FT spectrometers require a mirrorscanning mechanism with very high precision, resulting in large size and high cost. Low-cost, miniature spectrometers are key components that permit the realization of small-size, portable sensor solutions for applications such as color measurement and industrial process control. Therefore, recent investigations have dealt with low-cost, miniature spectrometers. 2,3A spatially modulated FT spectrometer (e.g., a Michelson interferometer with a tilted mirror and a photodiode array) is compact and has no moving parts. 4 However, stationary FT spectrometers have poor resolution and do not benefit entirely from the throughput advantage. We report here on a FT spectrometer with a moving mirror that is extremely compact ͑5 mm 3 4 mm͒ and has a scanning system that allows precise motion of the mirror. Low-cost fabrication is possible thanks to the use of silicon technology. 5A schematic of the actuator and the basic concept of FT spectroscopy are shown in Fig. 1. In FT spectroscopy we measure the intensity variation I R ͑d͒ as a function of the optical path difference d when a partially coherent plane wave is introduced into a Michelson interferometer. The relation between I R and d is known as an interferogram. The power spectrum B͑s͒ and the recorded intensity modulation I R ͑d͒ are related by a Fourier transform:where s is the wave number ͑s 1͞l͒. The theoretical resolution of a FT spectrometer is given bywhere d max 2Dx max and Dx max is the maximum displacement of the mirror. Electrostatic comb drive actuators are widely used in microelectromechanical systems because of their simple construction and reliable operation. These actuators permit a considerable displacement of as much as 100 mm, 6 but they cannot drive large loads. Therefore applications are mainly found in the area of optics in which no output force is needed. 6 Nevertheless, in many optical applications, such as Michelson interferometers and linear shutters, one would like to have a displacement that is linear to the applied voltage. Since a conventional comb drive actuator has a voltagedisplacement response that is quadratic, other actuator principles, such as piezoelectric or electrodynamic princip...

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We present a lamellar grating interferometer realized with microelectromechanical system technology. It is used as a time-scanning Fourier-transform spectrometer. The motion is carried out by an electrostatic comb drive actuator fabricated by silicon micromachining, particularly by silicon-on-insulator technology. For the first time to our knowledge, we measure the spectrum of an extended white-light source with a resolution of 1.6 nm at a wavelength of 400 nm and of 5.5 nm at 800 nm. The wavelength accuracy is better than 0.5 nm, and the inspected wavelength range extends from 380 to 1100 nm. The optical path difference maximum is 145 mm. The dimensions of the device are 5 mm 3 5 mm.Spectrometry is widely used in industry and research laboratories. There are many different methods that are used in a variety of fields. In particular, Fourier-transform spectroscopy is a powerful technique for investigating weak sources with high resolution. At present, an extended range of Fourier spectrometers is commercially available. However, high resolution involves an elevated degree of mechanism precision and therefore large size and high cost. Recently, lower-resolution miniature spectrometers have become attractive because of new applications, expanding opportunities in a remarkable variety of disciplines and industries.

b bstractMicro-optical electro-mechanical systems (MOEMS) technology, making use of existing silicon based fabrication techniques shows great potential for making complete miniaturized hybrid devices. Such technology has been used to make a Fourier transform spectrometer based on a time-scanning Michelson interferometer. An electrostatic comb drive actuator moves the scanning mirror over a distance of 40 mm. The measured resolution of the spectrometer is 6 nm at a wavelength of 633 nm. The dimensions of the device are 5=5=0.5 mm, and the depth of feature is 75 mm. During quality control of such devices it is necessary to check the dimensions of micron wide structures that are tens of microns deep, over areas of tens of square millimeters. In this work we have investigated the use of white light scanning interference (WLSI) microscopy for making rapid, non-destructive precision three-dimensional measurements. While a high axial precision can be achieved, an artifact has been observed with classical configurations that tend to extend the location of deep step discontinuities by up to 3 mm and so broaden narrow structures. With certain modifications in the optical configuration, this error can be considerably reduced. The results of this work demonstrate that WLSI shows great potential for the rapid and precise quality control of MOEMS devices.

We present a miniaturized Fourier transform spectrometer based on optical microelectro-mechanical system (OMEMS) technology. The spectrometer is a Michelson interferometer with one scanning mirror. An electrostatic comb drive actuator moves the mirror. The measured resolution of the spectrometer is 6 nm at a wavelength of 633 nm. In addition, we propose a method to integrate micro-optical components, like cylindrical lenses and beamsplitters, into the silicon chip with the actuated mirror.