Raman spectroscopy is a powerful tool for quantitative analysis of the composition and concentration of a certain analyte within a sample. In the application of physiological detection, such an optical measurement is usually carried out in the near-infrared region. The Raman signal is often small, for instance the ratio of Raman signal strength to excitation signal strength is less than 10−10. Moreover the Raman signal is ultra-sensitive to the measurement conditions, such as laser fluctuation, optical bleaching, temperature variation, the changes in sample size and sample shape and optical alignment. Therefore internal standard method is usually applied during the analysis of the Raman signal. The basic principle of internal standard method is to measure a sample signal and a standard signal simultaneously (or nearly simultaneously) and their ratio, which is invariant from the measurement conditions, is used in the quantitation. Conventionally, a Grating-CCD (or Grating-photodiode-array) spectrometer is used as the detector in these systems. However, these systems are expensive and throughput is limited by the grating at required spectral resolution.
Recent developments in Microelectromechanical systems (MEMS)-based spectrometer made it possible to use single detector to replace the CCD system in Raman signal detection system which significantly reduces the system cost. However, the throughput of such single-detector system is still limited by the use of grating. In order to achieve high throughput system, different designs have been disclosed. One of such design uses a sweeping light source, for instance a tunable laser, to obtain the Raman spectrum. Another approach uses a tunable filter, for instance an acousto-optical tunable filter, to obtain the Raman spectrum. Nonetheless, the costs of these new designs are not acceptable in constructing a home-used device for monitoring physiological parameters.