Ultramicromanipulation system with laser optical tweezer

光学技术的最新进展使我们能够开发出一种新的实验装置，可用于神经科学中的细胞生理学。在倒置微分干涉衬度显微镜的基础上增加视频图像处理系统，制成视频增强微分干涉衬度显微镜。使用这种V-DIC显微镜，可以检测直径为10至50 nm的金颗粒，并进行纳米测量。将激光束引入显微镜的落射照明光路，聚焦于样品上，用V-DIC显微镜观察激光束的捕获作用，激光束作为光镊夹持并移动金颗粒，跟踪并记录金颗粒的行为。首先用He-Ne激光（100 mW）作光镊，然后用Ar-Cr激光（100 mW）作光镊以提高光镊的性能。通过滑动显微镜载物台来粗略确定镊子的作用位置，然后通过光束控制器控制激光束在显微镜视野内的位置来更精确地确定镊子的作用位置。最后，激光束的位置由一个计算机辅助光束控制系统决定，该系统由一个带有纳米驱动器的反射镜和一对透镜组成的光路组成。进一步测试和证实了光镊的作用;光镊在其尖端捕获解离的单个神经细胞和丝状伪足，并将它们移位到不同的位置。当激光镊子夹持金颗粒时，观察到金颗粒标记的膜蛋白分子的运动受到激光镊子的调制。

Recent advance in optical technology allowed us to develope a new experimental set-up available for cellular physiology in neuroscience. A video-enhanced differential interference contrast (V-DIC) microscope was prepared by adding a video-image processing system to an inverted DIC microscope. With this V-DIC microscope it was possible to detect gold particles of 10 to 50 nm in diameter and to perform nano-meter measurement. When a laser beam was guided into epifluorecence illumination light path of the microscope and focused on specimens, trapping action of laser beam was observed with the V-DIC microscope ; laser beam acted as optical tweezers which could held and move gold particles, whose behavior was traced and recorded. At first He-Ne laser beam (100 mW) was employed for the tweezers, and later Ar-Cr laser beam (100 mW) to improve the ability of the tweezers. Acting site of tweezers was determined roughly by sliding a microscope stage and then more precisely by controlling the position of laser beam within microscope field by means of a beam controller. Finally the position of laser beam was decided with a computer-aided beam controlling system composed of a mirror with nanomover drive and a light path through a pair of lenses. Actions of the optical tweezers were further tested and confirmed ; the tweezers captured dissociated single nerve cells and filopodia at their tips, and displaced them to different positions. Movement of membrane protein molecules labelled with gold paticles was observed to be modulated by the laser tweezers when those gold particles were hold by the tweezers.