在实际应用中，平面测试仪主要用于工件的微米级测试，从而检验工件是否合格。高分辨率和高稳定度是平面测试仪研制的两大关键技术。采用分辨率扩展的方法可以提高分辨率；同时利用单片机和复杂可编程逻辑器件（CPLD）设计产生高稳定度的信号源，提高了系统的稳定度。内容包括工作原理，测试步骤和硬件设计，并介绍了提高精度的措施，主要由位移传感器，高稳定度信号源，单片机，信号处理单元四部分组成，具有高稳定度，高分辨率，低成本，操作简便的特点，目前已在重庆受拓利检测仪表有限公司正式投入使用。

In practical application, plane measuring instrument is mainly used to test flatness of workpiece in micro level, so that people can check if the workpiece is qualified or not. High resolution and high stabilization are two key technologies. The method of resolution extension is presented for improving the resolution of workpiece,and a signal source with high stabilization, which is designed by microcontroller and Complex Programmable Logic Device(CPLD), improves the stabilization of the system. The paper propose work principle and test step, the design of hardware,and introduces the measure for improving precision. The system is consisted of a position transducer, a signal source with high stabilization, a microcontroller and a signal processing unit. It has many advantages such as high resolution, high stabilization, low cost and simple operation, It also has been formally put to use in Chongqing Actaris Measurement Instrument Co.Ltd. now.

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