光学微透镜在光学成像、信号探测、生物传感等方面有重要的应用。针对现有固体微透镜难以变焦和生物不兼容的问题,提出将细胞内的叶绿体作为天然的微透镜,并研究了叶绿体微透镜的聚焦特性及其在光学成像和信号探测中的应用。研究结果表明,叶绿体微透镜对不同波长的入射光能产生聚焦效应。借助光镊产生的光力可实现叶绿体形状的可控变化,进而可实现对叶绿体微透镜焦距的调节,调节范围为15~45 μm。由于叶绿体微透镜具有光束聚焦特性,故其能够应用到亚波长结构的成像和荧光信号的增强中。在实验中,叶绿体微透镜实现了对线宽为200 nm的光栅结构和细胞内部肌动蛋白丝的光学成像,以及对量子点荧光信号的探测和增强。

Optical microlenses have important applications in optical imaging, signal detection, biosensing, and other fields. As existing solid microlenses have invariable focuses and are biologically incompatible, chloroplasts in cells are used as natural microlenses, and the focusing properties of chloroplast microlenses and the application of such microlens in optical imaging and signal detection are studied. The results show that chloroplast microlens can focus incident lights with different wavelengths. The optical force generated by optical tweezers can be leveraged to control the shapes of the chloroplasts, and thereby adjust the focal length of the chloroplast microlens. The focal length can be adjusted in the range of 15--45 μm. Due to their ability to focus light, chloroplast microlenses can be applied to the imaging of subwavelength structures and the enhancement of fluorescence signals. In the experiment, optical imaging of the grating structure with a linewidth of 200 nm and actin filaments inside cells, as well as detection and enhancement of the fluorescence signal of quantum dots are achieved by the chloroplast microlens.