[Study on dynamic spectrum and its frequency domain extracting method].
For non-invasive blood components detection using near-infrared spectrum, eliminating the influence of the individual difference is very important. In the non-invasive component measurement, the individual discrepancy refers to the difference of personal feature in measured tissues except the pulsatile component of artery blood, including hairs, horny layer, subcutaneous tissue, muscle, skeleton etc. It is declared that the individual discrepancy is different from the personal feature; it is an important factor blocking the practice of the technology. In the present article, a new method of detecting blood components is presented, which is based on the principle of photoplethysmography and Fourier transform. With this method, the influence of individual difference caused by skin and other tissues can be mostly eliminated, and the absorbance of artery blood could be obtained. The concept of the frequency domain extracting method was presented. The experiment was done and the dynamic spectrum which only evaluates the pulsatile part of the entire optical signal was obtained. The advantage of dynamic spectrum with frequency domain extracting method is analyzed. The result shows that the method can be realized and has many advantages.