We report the realization of the first planar optical tweezer trap system by a sheet of light. To visualize the trapping of the target object (dielectric bead or live cell) in a plane, an orthogonal widefield detection is employed. The planar / two-dimensional lightsheet optical tweezer (2D-LOT) sub-system is realized in an inverted microscopy mode with illumination from the bottom. A 1064 nm laser (power 54.5 W) is expanded and directed to a combination of cylindrical lens and high NA objective lens to generate a tightly-focussed diffraction-limited light sheet. The object to be trapped is injected in the specimen chamber (consists of two coverslips placed at a distance of approx 1 mm) using a syringe. The solution containing the objects stayed in the chamber due to the surface tension of the fluid. The illumination is carried out from Z-direction (with coverslip along XZ-plane) whereas, the detection is achieved perpendicular to the coverslip (along Y-axis). The orthogonal detection is employed to directly visualize the trapping in a plane. The characterization of system PSF estimates the size of light sheet trap PSF to be, 2073.84 μ² which defines the active trap region / area. Beads are tracked on their way to the trap region for determining the trap stiffness along Z and X i.e, k_z =1.13 ± 0.034 pN and k_x = 0.74 ± 0.021 pN. Results (image and video) show real-time trapping of dielectric beads in the trap zone (2D plane) generated by the light sheet. The beads can be seen getting trapped from all directions in the XZ-plane. Prolonged exposure to the light sheet builds up a 2D array of beads in the trap zone. Similar experiments on live NIH3T3 cells show cells trapped in the 2D trap. The potential of the planar trap lies in its ability to confine objects in two dimensions, thereby opening new kinds of experiments in biophysics, atomic physics, and optical physics.

中文翻译：

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通过光片照明和正交宽场检测实现平面光镊陷阱 (2D-LOT) 系统

我们报告了第一个通过光片实现的平面光镊陷阱系统。为了可视化平面中目标物体（介电珠或活细胞）的捕获，采用正交宽场检测。平面/二维光片光镊 (2D-LOT) 子系统以倒置显微镜模式实现，并从底部照明。 1064 nm 激光（功率 54.5 W）被扩展并引导至柱面透镜和高 NA 物镜的组合，以产生紧密聚焦的衍射极限光片。使用注射器将要捕获的物体注入样品室（由两个间隔约 1 毫米的盖玻片组成）。由于流体的表面张力，含有物体的溶液留在腔室中。照明从 Z 方向进行（盖玻片沿 XZ 平面），而检测是垂直于盖玻片（沿 Y 轴）实现的。采用正交检测来直接可视化平面中的捕获。系统 PSF 的表征估计光片陷阱 PSF 的大小为 2073.84 μ ²，它定义了有源陷阱区域/面积。珠子在前往陷阱区域的途中被跟踪，以确定沿 Z 和 X 的陷阱刚度，即 k _z = 1.13 ± 0.034 pN 和 k _x = 0.74 ± 0.021 pN。结果（图像和视频）显示了光片生成的捕获区（2D 平面）中电介质珠的实时捕获。可以看到珠子从 XZ 平面的各个方向被困住。长时间暴露在光片下会在捕获区形成二维珠子阵列。对活 NIH3T3 细胞进行的类似实验显示细胞被困在 2D 陷阱中。平面陷阱的潜力在于它能够将物体限制在二维空间中，从而为生物物理学、原子物理学和光学物理学开辟了新的实验类型。