用于在体捕获红细胞的表面等离子体超透镜光镊系统的研究

光镊技术在活体里对较深组织的红细胞进行无创伤性的捕获具有重要的意义。然而由于聚焦光斑在组织里的散射和光镊系统自身的像差，使得聚焦光斑在较深的组织无法提供足够的梯度力，对红细胞进行捕获有难度。目前大多数改进系统焦斑质量的方法是通过光镊系统其他部件的像差补偿显微物镜的像差。光镊系统里像差补偿得不好会直接限制捕获细胞的稳定性和组织里的捕获深度。本课题提出基于表面等离子体天线阵列的超透镜，拟设计出的超透镜能在1064和900纳米的入射光消掉球差。经过以上超透镜聚焦形成的光斑能在活体里深度捕获红细胞，提高捕获效率并且降低捕获激光功率。该表面等离子体超透镜由两组分别在两个波长共振的天线阵列组成，可将两个波长的光聚焦到邻近的位置，产生的双光束光镊在活体的血流环境下用以测量获得红细胞的变形指数。

Trapping red blood cells in vivo at a deep position underneath the skin non-invasively is of great importance for biomedical science. However, due to the strong scattering of the light in the tissue and aberrations of the optical system, the gradient force generated from the focused beam is not large enough to trap a blood cell at a deep position. In order to improve the quality of the focused beam, various optical designs are employed to compensate the aberrations of the objective. Therefore the stability of the trapping and the trapping depth in the tissue are limited if the aberration of the system is not optimized well. We propose an optical tweezer system based on a super-lens, which is composed of plasmonic antenna arrays. The super-lens has the ability of eliminating the spherical aberrations at the wavelengths of 1064nm and 900nm. The focused optical beam through the super-lens can increase the trapping depth of the blood cell in vivo, and in the mean while improve the trapping efficiency which leads to a lower input laser power. A novel design of plasmonic super-lens constitutes two antenna arrays resonant at the two above wavelengths correspondingly, which can focus dual beams to neighboring positions at the focal plane. And the dual-beam optical tweezer system is utilized to measure the deformation index of blood cells in vivo.