With the increasing application of fiber lasers, the reliability of fiber lasers has attracted more and more attention, including the reliability of laser output performance, the reliability of electronic components, the reliability of optical devices, the reliability of systems, etc. Wait. Most of these are closely related to the thermal properties of the laser itself. In addition, the temperature has a great influence on the performance of the laser, especially the output power and output stability of the laser.
The heat of the fiber laser mainly comes from the pump source and the gain cavity. For the pump source, its conversion efficiency is about 50%, which also means that an energy equivalent to the output optical power is generated in the form of heat. If the heat cannot be dissipated in time, the temperature of the internal chip will rise rapidly, and the center wavelength of the laser will drift as the temperature rises. For the gain cavity, only a part of the pump light is converted into laser output after entering the active gain fiber, and the rest of the energy is converted into heat energy. Thermal energy will increase the temperature of the gain medium, resulting in broadening of the fluorescence spectrum and short lifetime of spontaneous emission, thereby reducing the energy conversion efficiency. Therefore, thermal management has a non-negligible significance for fiber lasers.
At present, the commonly used thermal management technologies are mainly air-cooled and water-cooled. Among them, the air-cooled heat dissipation technology is mainly used in low-power pulsed lasers and low-power continuous lasers. Most of the medium and high-power fiber lasers use water-cooled heat dissipation as the main heat dissipation. measure.
Two main ways to dissipate heat
1. Water cooling
As the name suggests, water cooling is the use of water to take away heat through a heat exchanger (such as a water cooling plate). Its working principle is also very simple, that is, the cold water in the chiller flows into the heat exchanger through the water pipe, and then comes out from another port of the heat exchanger, and then flows back to the chiller through the water pipe. Heat is carried away from the inside of the laser.
The water-cooled heat dissipation method has a simple structure and is easy to maintain; the heat dissipation capacity is strong and the temperature uniformity is good. The cooling performance of the laser can be improved by using a chiller with a larger cooling capacity. At present, there are more than 500 manufacturers integrating and selling handheld laser welding machines on the market, and they generally use water cooling. However, in addition to the laser itself, the hand-held laser welding machine with water cooling also requires additional chillers and water, which results in a substantial increase in the overall volume and weight of the equipment, and limited use environments.
2. Air cooling
In a broad sense, air-cooled heat dissipation refers to the use of fans to enhance air convection and complete heat exchange inside the machine. With the improvement of technology, major laser manufacturers have begun to set foot in the field of air cooling and heat dissipation. In June last year, the global fiber laser giant I company launched the air-cooled LightWELD 1500W hand-held laser welding product; in August, GW launched the air-cooled A1500W intelligent laser welding machine for the first time in China; this month, our company also released the RL-F1000 Air-cooled laser welding machine.