Development of a surface encoder for next generation three-axis precision stages

本研究开发了一种由正弦角网格和二维斜率传感器组成的表面编码器，用于多自由度平面运动测量。角度网格具有三维微结构表面，它是x和y方向上周期正弦波的叠加。基于激光的坡度传感器用于读取网格表面的局部坡度曲线。X和y位置以及围绕X、y和z轴的倾斜运动可以通过使用多个传感器来检测，最大速度为550mm/s。用于在XY平面上进行纳米位置测量的双通道表面编码器。通过采用双通道光学布局，传感器的灵敏度是单通道表面编码器的两倍。实现了2nm的分辨率。选择了快速伺服刀具金刚石车削加工角度网格的方法。所构建的快速刀具伺服系统采用压电管作动器驱动金刚石刀具，电容探头作为反馈传感器，在闭环模式下具有约4 kHz的带宽和几纳米的刀具位移精度。提出了一种基于干涉显微镜图像二维离散傅里叶变换（DFT）的栅格表面评价方法。φ 150mm网格曲面的加工结果表明了该加工系统的有效性。制作的最小角栅间距为10 μm。本文还开发了一种用于在大面积薄膜上制备角度网格的UV辊复制技术。该编码器已应用于地面电机驱动平台的五自由度精密定位。表面电机由放置在同一表面上的一对直线电机组成。所述直线电机的磁阵和定子绕组分别安装在压板（运动元件）和级座上。平面编码器的角栅安装在由空气轴承悬浮的平台上。坡度传感器和空气轴承座固定在平台基座上，使平台的运动不受电子电缆和空气软管的影响。表面编码器也已应用于索耶电机驱动阶段。少

This research has developed a surface encoder consisting of a sinusoidal angle grid and a two-dimensional slope sensor for multi-degree-of-freedom planar motion measurement. The angle grid has a three dimensional micro-structured surface, which is a superposition of periodic sinusoidal waves in the X-and Y-directions. The laser-based slope sensor is used to read local slope profiles of the grid surface. The X-and Y-positions together with tilt motions about the X-, Y-and Z-axes can be detected by using multiple sensors with a maximum speed of 550mm/s. a double pass surface encoder for nanometer position measurement in the XY plane. By using a double pass optical layout, the sensitivity of the sensor becomes twice as much as that of the single pass surface encoder. A resolution of 2 nm has been realized.Diamond turning with a fast tool servo has been chosen as the fabrication method for the angle grid. The constructed fast tool servo, which employs a piezoelectric tube actuator to actua … More te the diamond tool and a capacitance probe as the feedback sensor, was confirmed to have a bandwidth of approximately 4 kHz and a tool displacement accuracy of several nanometers in the closed-loop mode. An evaluation technique based on the two-dimensional discrete Fourier transform (DFT) of interference microscope images has been developed to evaluate the fabricated grid surface effectively. The fabrication result of a grid surface over an area of φ150 mm has indicated the effectiveness of the fabrication system. The fabricated minimum pitch of the angle grid is 10 μm. A UV roller replication technique has also been developed to fabricate the angle grid on large area films.The surface encoder has been applied for surface motor-driven stages for five degree-of-freedom precision positioning. The surface motor consists of pairs of linear motors placed on the same surface. The magnetic array and the stator winding of the linear motor are mounted on the platen (the moving element) and the stage base, respectively. The angle grid of the surface encoder is mounted on the platen of the stage which is levitated by air-bearings. The slope sensors and the air-bearing pads are fixed on the stage base so that the motion of the platen is not affected by the electronic cables and air hoses. The surface encoder has also been applied to Sawyer motor driven stages. Less