視覺檢測系統中工業鏡頭的選擇五要素
發布時間：
2023-02-10 11:30
工業相機、圖像采集卡、照明光源、分析軟件和工業鏡頭是組成機器視覺檢測系統的重要元件，其中關鍵的元件還是工業鏡頭。視覺檢測系統若想完全發揮作用，選擇工業鏡頭前必須要考慮到以下五個要素：
Industrial camera, image acquisition card, lighting source, analysis software and industrial lens are important components of machine vision inspection system, among which the key component is industrial lens. If the visual inspection system wants to play a full role, the following five factors must be considered before selecting industrial lens:
1.運行環境
Operating environment
機器視覺檢測系統的工作環境不同所選用的工業鏡頭會有所區別。因為物體的反射系數、光線、溫度、振動和污染物等都會影響鏡頭的正常工作。若是在高溫環境下，可能因為鏡頭里光學元件的熱膨脹出現問題。并不是所有的鏡頭都可以適應溫度變化，在檢測熱物體時，使用工作距離比較長的鏡頭，也就是說我們要根據視覺檢測系統的工作環境選擇適合的鏡頭。
The working environment of machine vision inspection system is different, and the industrial lens selected will be different. Because the reflection coefficient of the object, light, temperature, vibration and pollutants will affect the normal operation of the lens. If it is in a high temperature environment, it may be due to the thermal expansion of the optical elements in the lens. Not all lenses can adapt to temperature changes. When detecting hot objects, use lenses with long working distance, that is to say, we should select the appropriate lens according to the working environment of the visual inspection system.
2.檢測物體類別和特性
Detection object category and characteristics
鏡頭對于物體特征的解析能力依賴于特征的對比是否強烈。確定系統解析度、或者物體解析特征的方法，可以使用諸如倫奇刻線法這樣的解像力方法。鏡頭在指定光線條件下辨識特定寬度的線耦或者點距的能力，決定了它的解析度。解析度通常被模塊轉換功能（MTF）以圖像的方式顯示出來。
The ability of lens to analyze object features depends on whether the contrast of features is strong. In order to determine the resolution of the system, or the analytic characteristics of an object, we can use the image force method such as lunge's method. The resolution of the lens is determined by its ability to identify the line coupling or point distance of a specific width under the specified light conditions. Resolution is usually displayed in the form of images by the module conversion function (MTF).
3.景深或者焦距
Depth of field or focal length
景深效果（DOF）是指由于物體移動導致的模糊。DOF是完全在焦距范圍內的物體深度，是保持理想對焦狀態下物體允許的移動量，從焦距前后移動。當物體的放置位置比工作距離近或者遠的時候，它就位于焦外了，這樣解析度和對比度都會受到不好的影響。出于這個原因，DOF同指定的解析度和對比度相配合。當景深一定的情況下，DOF可以通過縮小鏡頭孔徑（也就是增加F/#值）來變大，同時也需要光線增強。
Depth of field effect (DOF) refers to blurring caused by moving objects. DOF is the depth of the object completely within the focal length range, and the allowable movement of the object under the ideal focusing state, moving forward and backward from the focal length. When the object is placed closer or farther than the working distance, it is out of focus, which will affect the resolution and contrast. For this reason, DOF matches the specified resolution and contrast. When the depth of field is fixed, the DOF can be increased by reducing the aperture of the lens (i.e. increasing the F / #) value, and light enhancement is also required.
4.加載
Loading
很多相機鏡頭需要平穩加載，但是當物體和鏡頭之間的距離受到限制，改變鏡頭與圖像之間的距離，就可以改變工作距離。加載限制，包括用于艱苦環境的保護外殼，必須具有足夠的柔性，可以根據工作距離進行調整。
Many camera lenses need to be loaded smoothly, but when the distance between the object and the lens is limited, changing the distance between the lens and the image can change the working distance. The loading limits, including protective enclosures for harsh environments, must be flexible enough to be adjustable according to the working distance.
5.檢測距離
Detection distance
當圖像在焦距范圍內的時候，物體和照相機鏡頭前端的距離。它限制了視覺系統以及和視覺系統一起工作的設備所需要的空間。在極限范圍內，通過鏡頭重新對焦，可以改變工作距離。
The distance between the object and the front of the camera lens when the image is in focus. It limits the space required by the vision system and the devices that work with it. Within the limits, the working distance can be changed by refocusing the lens.
由此可見，合適的鏡頭選擇對于機器視覺檢測系統發揮著非常重要的作用。
Therefore, appropriate lens selection plays a very important role in machine vision detection system.
視覺檢測系統,機器視覺檢測技術