简析三坐标光栅尺基本知识 A Brief Analysis of Basic Knowledge About Coordinate Measuring Machine Linear Encoders

​作为三坐标上的关键部件，光栅尺是非常精密的，利用光栅的光学原理工作的测量反馈装置，光栅线位移传感器经常应用于三坐标等精密机器中，可用作直线位移或者角位移的检测。其测量输出的信号为数字脉冲，具有检测范围大，检测精度高，响应速度快的特点。

As a key component of a coordinate measuring machine, the linear encoder is extremely precise. It is a measurement feedback device that works on the optical principle of gratings. The grating linear displacement sensor is often used in precision machines such as coordinate measuring machines and can be used for detecting linear displacement or angular displacement. Its measurement output signal is a digital pulse, and it features a large detection range, high detection accuracy, and fast response speed.

光栅尺的工作原理

The Working Principle of Linear Encoders

常见光栅的工作原理都是根据物理上莫尔条纹的形成原理进行工作的。当使指示光栅上的线纹与标尺光栅上的线纹成一角度来放置两个光栅尺时，必然会造成两光栅尺上的线纹互相交叉。在光源的照射下，交叉点近旁的小区域内由于黑色线纹重叠，因而遮光面积最小，挡光效应最弱，光的累积作用使得这个区域出现亮带。相反，距交叉点较远的区域，因光栅尺不透明的黑色线纹的重叠部分变得越来越少，不透明区域面积逐渐变大，即遮光面积逐渐变大，使得挡光效应变强，只有较少的光线能通过这个区域透过光栅，使这个区域出现暗带，从而便形成了我们所见到的莫尔条纹。

The working principle of common linear encoders is based on the physical formation principle of Moiré fringes. When the scale grating and the index grating are placed at an angle to each other so that their lines cross, the lines on the two gratings inevitably intersect. Under illumination from a light source, in the small region near the intersection points, the black lines overlap, so the light-blocking area is smallest and the blocking effect is weakest; the cumulative effect of light causes a bright band to appear in this region. Conversely, in regions farther from the intersection points, the overlapping portion of the opaque black lines becomes progressively smaller, the opaque area gradually increases—that is, the light-blocking area gradually increases—making the blocking effect stronger, so that only a small amount of light can pass through this region, causing a dark band to appear. In this way, the Moiré fringes we observe are formed.

光栅尺的维护和保养

Maintenance and Care of Linear Encoders

1、光栅尺外尽可能外加保护罩，并及时清理溅落在尺上的切屑和油液，严格防止任何异物进入光栅尺壳体内部。

1. If possible, add a protective cover on the outside of the linear encoder, and promptly clean off chips and oil that splash onto the scale. Strictly prevent any foreign matter from entering the interior of the linear encoder housing.

2、定期检查各安装联接螺钉是否松动，尤其是固定读数头的螺丝。很多时候，读数头固定螺丝松动会造成机床直线轴暴走或不能回参考点。

2. Regularly check whether the mounting screws are loose, especially the screws securing the readhead. In many cases, loose readhead fixing screws can cause the machine's linear axis to run away or fail to return to the reference point.

3、为保证光栅尺传感器使用的可靠性，可每隔一定时间要用无水乙醇清洗擦拭光栅尺面及指示光栅面，保持玻璃光栅尺身的清洁。

3. To ensure the reliability of the linear encoder sensor, the scale surface and the index grating surface should be cleaned and wiped with anhydrous ethanol at regular intervals to keep the glass scale body clean.

4、光栅尺严禁剧烈震动及摔打，以免破坏光栅尺，如光栅尺断裂。

4. The linear encoder must not be subjected to severe vibration or impact, so as to avoid damaging it, such as causing the scale to break.

5、在安装光栅尺和读数头时，特别要注意读数头与光栅尺的距离，或远或近都可能造成读数头的损坏或光栅尺壳体内的刻度的破坏，甚至报废光栅尺。

5. When installing the linear encoder and the readhead, special attention should be paid to the distance between the readhead and the scale. Being either too far or too close may cause damage to the readhead or to the graduations inside the scale housing, and may even render the linear encoder unusable.

如果可以的话，查阅说明书查找防止光栅尺的周围的油、液、气进入光栅尺内部的方法，避免污染光栅尺。

If possible, consult the manual to find methods for preventing oil, liquid, and gas around the linear encoder from entering its interior, so as to avoid contaminating the linear encoder.