A new method for measurement of the pitch deviation of a scale grating by an optical angle sensor based on the laser autocollimation is proposed. In the proposed method, the scale pitch deviation is evaluated through detecting the change in the angles of diffraction of the first-order diffracted beams, which is associated with the change in the scale pitch deviation. The optical angle sensor unit is designed to measure the angles of diffraction of both the positive and negative first-order diffracted beams simultaneously so that the influences of the scale form error and the roll error motion of the linear slide for the scanning of a linear scale can be canceled through the differential operation. The optical angle sensor unit based on the laser autocollimation is newly designed and developed, and the pitch deviation of a linear scale from a commercial interferential scanning-type linear encoder is evaluated by the developed setup to verify the feasibility of the proposed method in experiments. The scale form error obtained through the differential operation is also compared with the one evaluated by a commercial Fizeau interferometer. Furthermore, the uncertainty analysis on the proposed pitch deviation measurement is carried out based on GUM to theoretically verify the feasibility of the proposed method.

提出了一种基于激光自准直的光学角度传感器测量光栅尺间距偏差的新方法。在所提出的方法中，通过检测一阶衍射光束的衍射角的变化来评估标尺间距偏差，该变化与标尺间距偏差的变化相关。光学角度传感器单元设计用于同时测量正和负一阶衍射光束的衍射角，以使刻度尺的形状误差和线性滑块的滚动误差运动对线性刻度尺扫描的影响可以通过微分操作取消。新设计开发了基于激光自准直的光学角度传感器单元，通过开发的装置评估了线性标尺与商用干涉扫描型线性编码器的螺距偏差，以验证该方法在实验中的可行性。通过微分运算获得的标度形式误差也与通过商用Fizeau干涉仪评估的标度形式误差进行了比较。此外，基于GUM对所提出的螺距偏差测量进行了不确定性分析，从理论上验证了所提出方法的可行性。