应用浮动基准法修正光谱光源漂移影响的模拟验证

近红外无创伤血糖检测目前面临的挑战主要是测量条件难以保证稳定、测量系统及被测对象自身的背景变化等问题，导致很难从背景变动的光谱中提取出糖浓度变化信息。经过多年的实验研究发现应用浮动基准参考测量法有望消除仪器漂移及被测对象自身背景变动的影响。但是浮动基准位置因人及测量部位不同而异，在不同的测量波长下其浮动基准点位置也不同，因此，欲在实验中验证浮动基准法的光谱修正效果需要测量出与入射光位置不同径向距离处的漫反射光强，然而在实际实验中位置精度很难保证。为此，研究了用模拟实验的方法验证多波长下浮动基准法对光源漂移所引起的光谱变化的修正效果，基于Monte Carlo模拟，分别采用浓度为5%和10%的Intralipid溶液作为被测样品，通过改变入射光子数模拟光源漂移的影响。得到模拟的光谱数据后，利用浮动基准法对其进行处理，并分别对浮动基准法修正前后的光谱数据进行偏最小二乘建模分析，将预测结果进行比较发现：两种浓度Intralipid溶液在存在光源漂移影响情况下修正后的模型预测精度预测均方根误差(RMSEP)相比于修正前分别减小了98.57%(5% Intralipid)和99.36%(10% Intralipid)。表明浮动基准法在消除光源漂移的影响方面效果明显。

The Validation of the Effect of Correcting Spectral Background Changes Based on Floating Reference Method by Simulation

There are some challenges in near-infrared non-invasive blood glucose measurement, such as the low signal to noise ratio of instrument, the unstable measurement conditions, the unpredictable and irregular changes of the measured object, and etc. Therefore, it is difficult to extract the information of blood glucose concentrations from the complicated signals accurately. Reference measurement method is usually considered to be used to eliminate the effect of background changes. But there is no reference substance which changes synchronously with the anylate. After many years of research, our research group has proposed the floating reference method, which is succeeded in eliminating the spectral effects induced by the instrument drifts and the measured object’s background variations. But our studies indicate that the reference-point will changes following the changing of measurement location and wavelength. Therefore, the effects of floating reference method should be verified comprehensively. In this paper, keeping things simple, the Monte Carlo simulation employing Intralipid solution with the concentrations of 5% and 10% is performed to verify the effect of floating reference method used into eliminating the consequences of the light source drift. And the light source drift is introduced through varying the incident photon number. The effectiveness of the floating reference method with corresponding reference-points at different wavelengths in eliminating the variations of the light source drift is estimated. The comparison of the prediction abilities of the calibration models with and without using this method shows that the RMSEPs of the method are decreased by about 98.57%(5%Intralipid)and 99.36%(10%Intralipid)for different Intralipid. The results indicate that the floating reference method has obvious effect in eliminating the background changes.