基于显微数字全息的生物薄膜折射率的测量

The refractive index measurement of bio-film based on digital holographic microscopy

提出了一种基于显微数字全息相位重构图像的生物薄膜折射率的简便测量方法。利用角谱法对生物薄膜的显微数字全息图像进行重构,得到其复振幅分布,从中获得激光通过生物薄膜后的相位变化与薄膜厚度、薄膜中液体的折射率及薄膜折射率间的定量关系。通过等厚干涉和阿贝折射仪测得膜的厚度与液体的折射率,再从定量的相位变化中获得生物薄膜的折射率。以洋葱内表皮细胞层折射率的测量为例,进行了相应的实验验证,得到了波长为632.8nm下的折射率。理论与实验均表明,该方法是有效和切实可行的。

The phase reconstruction image of digital holographic microscopy is presented to measure the refractive index of biological film.The angular spectrum method is employed to reconstruct the phase image.The quantitative relationship between the thickness of the film,the refractive index of the film and the refractive index of the liquid among the film is determined from the phase image. The thickness of the film and the refractive index of the liquid can be measured easily using wedge interference and Abbe refractometer respectively,and then the refractive index of the film is obtained.As an example,the refractive index of the inner film of an onion has been measured at 632.8 nm laser wavelength.The theory and experimental results prove that the method is effective and feasible.