Flat-field focusing lens, also known as field lens or f-theta lens, is a professional lens system, the purpose is to form a uniform focused spot of laser beam in the entire marking plane, it is one of the important accessories of laser marking machine.
If the laser marking machine does not use a professional field lens, the beam will not be able to enter the designated focal point vertically. In general terms, the function of the field lens is to focus the incoming beam to a beam spot and the focal length will not varies with the deflection angle.
Another point is the focal length. It has a certain relationship with the working distance, but the focal length is not equal to the working distance.
When marking large objects, the required field lens also needs to be larger. Many manufacturers usually like to scan the lens with a large range of marking, but blindly increase the scanning area, that is, when the scanning area reaches a certain level, the diameter of the light spot becomes larger, the distortion increases, and the power density of the laser decreases faster. The longer working distance will lead to the loss of laser energy, which is not conducive to precision marking.
A common problem is insufficient marking depth or uneven marking on high-density materials.
In general, the choice of field lens is mostly the choice of focal length, and its measurement factors mainly include the size of the specific marking object; the size of the required marking range; the fineness of the processing and the overall matching of the equipment.
SUNINE laser laser marking machine adopts high-transmittance coated fused silica field lens, which is used to greatly improve the ability to meet the actual needs of customers.