加权非负最小二乘光子相关光谱纳米颗粒粒径反演方法

Photon Correlation Spectroscopy for Nano-particle Diameter Measurement with Weighted Nonnegative Least Squares

为了降低采用光子相关光谱法进行纳米颗粒测量时噪音对颗粒粒径反演结果的影响,提出了一种基于加权非负最小二乘法的光子相关光谱纳米颗粒粒径计算方法.该方法以光子相关光谱自身作为权值,推导出反演算法的离散模型,避免了接近零点的测量数据波动对测量结果的影响.利用光子相关光谱纳米检测实验平台对90nm、190nm及混合的乳胶颗粒进行实验研究,并与传统非负最小二乘法反演结果进行了对比.60s测量时间的30次实验数据表明:对单峰颗粒群进行反演时,该方法多次测量结果与传统非负最小二乘法结果相近,但是多次重复测量的方差较小,证明该方法重复性较好;对多峰颗粒群进行反演时,该方法反演结果更接近颗粒的真实值,而非负最小二乘法其反演结果与真实值有较大偏离.在不同测量时间的实验数据表明:测量较短的情况下,该方法反演结果方差较小,能在更短的采样时间情况下,获得更准确的测量结果.

To reduce the effect of noise on inversion result of grain diameter m nano-parume diameter measurement using photon correlation spectroscopy, a nano-particle diameter computing method is proposed based on photon correlation spectroscopy with nonnegative least squares. Photon correlation spectroscopy itself is as the weight to derive discrete model of inversion algorithm and avoid the influence of data fluctuation close to zero. The 90 nm, 190 nm and mixed latex particles are measured by the photon correlation spectroscopy equipment and compared with the traditional nonnegative least squares. The 30 experimental data in 60 seconds indicate that in the inversion of unimodal paticle group, the results of present method is close to traditional nonnegative least squares but variance of multiple repeated measurement is smaller which proves good repeatability of present method; in the inversion of multimodal particles, the results of present method are much closer to true values of diameters, however, the results of nonnegative least squares deviate more from true values. Experimental data of different measurement time show that in a short period of time, variance of present method is smaller and it can obtain more accurate results in a shorter period of time.