Design and testing of a four-probe optical sensor head for three-axis surface encoder with a mosaic scale grating
Design and testing of a four-probe optical sensor head for three-axis surface encoder with a mosaic scale grating
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DOI：
10.1088/0957-0233/25/9/094002
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发表时间：
2014-09-01
影响因子：
2.4
通讯作者：
Gao, Wei
中科院分区：
文献类型：
--
作者：
Shimizu, Yuki;Ito, Takeshi;Gao, Wei
介绍了一种用于三轴拼接尺度光栅表面编码器的四探头光学传感器头的设计研究。拼接尺度光栅是将多个二维反射型尺度光栅在平面上排列成一个矩阵，从而扩展三轴表面编码器沿X轴和y轴的测量范围。基于几何光学原理，设计了一种由一个激光二极管和两个分束器组成的四探头单元的光学布局，使四探头能够在矩阵中对齐。将所设计的四探针单元集成到三轴表面编码器的光学传感器头中。在三轴表面编码器中利用XY光栅衍射光束叠加产生的干涉信号，使得拼接尺度光栅沿X、Y、z轴的平移位移运动可以被四个探头中的每个探头同时检测到。实验验证了所设计的四探头光学传感器头和所提出的马赛克尺度光栅概念在扩大三轴表面编码器沿X和y方向运动主轴的测量范围方面的可行性。比较了各探头的测量灵敏度，并通过线性矩阵计算对其进行补偿。研究了各探头的测量分辨率和非线性。另外，将四个探头的测量结果拼接在一起，测量了在拼接尺度光栅沿x轴方向进行远距离平移时，线性台阶的xyz方向平移运动。
This paper presents a design study of a four-probe optical sensor head for a three-axis surface encoder with a mosaic scale grating. As the mosaic scale grating, multiple two-dimensional reflective-type scale gratings are aligned in a matrix on a plane so that measurement ranges of the three-axis surface encoder along the X- and Y-axes can be extended. An optical layout for a four-probe unit, which consists of a laser diode and two beam splitters, was designed based on geometrical optics so that four probes aligned in the matrix can be generated. The designed four-probe unit was integrated into the optical sensor head of the three-axis surface encoder. Interference signals generated by the superimposition of diffraction beams from the XY gratings were utilized in the three-axis surface encoder so that the translational displacement motions of the mosaic scale grating along the X-, Y- and Z-axes can be detected simultaneously by each probe in the four probes. Experiments were carried out to verify the feasibility of both the designed four-probe optical sensor head and the proposed concept of the mosaic scale grating for expanding the measurement range of the three-axis surface encoder along the X- and Y-directional primary axes of motion. Measurement sensitivity of each probe was compared, and its compensation was carried out by linear matrix calculations. Measurement resolution and nonlinearity of each probe were also investigated. In addition, XYZ-directional translational motions of a linear stage when a long-range translational motion along the X-axis was given to the mosaic scale grating were measured by stitching the measured results by the four probes.