为了检测全息光镊的捕获能力, 将基于视觉原理的光学测量系统用于全息光镊三维光阱刚度的测量.光学系统采用对称分布的双光源照射样品池, 形成两个像点, 通过跟踪像点位移获取被全息光镊捕获微球的三维位移信息.结合流体力学法测出本光学系统中单、双光阱的三维光阱刚度.实验结果表明: 单光阱中, 沿X、Y水平方向光阱刚度相差不大, 而轴向光阱刚度落在水平方向的1/3~1/4范围; 双光阱中, 离光轴(即衍射中心)近的光阱其三维刚度要比距离光轴稍远的光阱要大, 说明越靠近衍射中心, 光的衍射效率越高, 产生的光阱捕获能力也越强.

In order to test the capture ability of holographic optical tweezers, an optical measurement system based on vision theory was used to measure the 3D trap stiffness of holographic optical tweezers. In the optical system, two symmetrically distributed light sources irradiated the sample cell to form two images. The 3D positions of the microspheres captured by the holographic optical tweezers were obtained by tracking the displacements of their images. Combined with hydrodynamic method, the trap stiffness of the single and double optical traps was measured. The experimental results show that in a single optical trap, there is little difference between X and Y horizontal trap stiffness, and the axial trap stiffness falls in the range of 1/3 to 1/4 of the horizontal direction; in double optical traps, the three-dimensional stiffness of the optical trap near the optical axis is larger than that an a far distance, which demonstrates that the closer to the diffraction center, the higher the diffraction efficiency of light, and the stronger the capture ability of the optical trap.