The main lighting mode of image measuring instrument
lighting is a very key link in the measurement process of image measuring instrument. A good lighting scheme plays an important role in accurately measuring various values of the measured object
in image measuring instruments, there are three main lighting methods: surface light lighting, contour light lighting and coaxial light lighting. The surface light and contour light illumination methods are relatively common, and the coaxial light illumination plays a vital role in the measurement of the serious consequences of 10 points caused by the failure to recover once the fatigue of some special workpieces occurs. In addition to the surface light and contour light, the automatic image measuring instrument developed by Tianzhun company () adds coaxial light illumination, which can be specially used to measure the hole depth and blind hole depth of the workpiece, and has a very unique role in measuring reflective and mirror workpieces, as well as a strong auxiliary role in the accuracy of grasping primitives
surface light illumination: surface light illumination generally adopts ring or dot illumination, which is on the same side as the camera. Circular lamp is a commonly used surface light illumination method, which is easy to install on the lens and can provide sufficient illumination for the diffuse reflection surface. Surface light illumination uses surface light sources. The surface light source provides general illumination for the surface of the workpiece. The current application trend is to use the annular surface light source to provide surface illumination in multiple directions and incident angles. The image measuring instrument of Tianzhun company provides surface light lighting in Zone 8 of the 6th Ring Road. A total of 48 independent zones can be controlled. Each zone can independently control the switch and brightness, and the brightness level is as high as 200. And the incident angle of each ring is different, which ensures that different lighting modes can be provided for different workpieces
contour lighting: contour lighting is to place the light source on the back of the object. This lighting method is very different from other lighting methods, because the image can be repaired by grinding, and the analysis is not reflected light but incident light. Contour lighting produces a strong contrast. When using contour lighting technology, the surface features of the object will be lost, but the contour information of the object can be clearly obtained. The light source illuminating the contour light is called the contour light source. The contour light source distinguishes the light transmitting part from the light impermeable part. The light transmitting part is white and the light impermeable part is black. In this way, a black-and-white contrast picture is obtained. A very important point of contour light is to ensure that the emitted light is a parallel light, so as to ensure that different intensities of light will not cause changes in the contour of the workpiece, thereby affecting the accuracy of measurement
coaxial light illumination: coaxial light illumination refers to the light in the same direction as the axis of the camera irradiates the surface of the object. Coaxial light illumination uses a special semi reflective mirror to reflect light to the direction of the lens axis of the camera. The semi reflecting mirror only allows light reflected from the surface of the object and perpendicular to the lens to pass through. The illumination technology provided by the coaxial light source is very useful for realizing the uniform illumination of the surface of flat objects with mirror characteristics, which can be economical for some specific experiments. In addition, this technology can also highlight the surface angle change part, because the reflected light on the surface that is not perpendicular to the camera lens will not enter the lens, resulting in a darker surface
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