How Are Industrial Lasers Cooled?

There are several varieties of industrial lasers. Some lasers, such as fiber lasers, have specific arrangements that enable spreading the heat they generate over a larger surface area. This arrangement gives fiber lasers better cooling characteristics over other media. Other lasers need extra cooling arrangements to remove the heat they generate. For example, ion lasers generate extreme heat when active and need elaborate cooling methods. Other lasers, emitting energy in the microwave and far-infrared region of the spectrum such as carbon dioxide lasers are immensely powerful, and cut hard material such as steel. The laser essentially melts through the material it focuses on. The problem is these industrial lasers have a limited surface area from where to exchange heat.

Although people traditionally use thermoelectric modules as heat exchangers, their efficiency has always limited their application. Now, thermoelectric modules are available which exhibit high heat flux density and are able to achieve higher heat pumping capacity compared to standard thermoelectric modules.

For instance, the UltraTEC series of thermoelectric modules from Laird has heat-pumping capacity of up to 340 Watts, which is fully adequate to cool applications such as industrial lasers that offer only a limited surface for heat exchange.

Industrial laser applications are numerous, including drilling, additive manufacturing, micro machining, welding, and cutting. Irrespective of the application, industrial lasers generate tremendous amounts of heat, which needs to be quickly and effectively removed to allow the laser to perform long-term and properly. Cooling lasers efficiently has always been a significant challenge for the industry.

Typical methods of cooling include transferring the excess heat by conduction or convection. Air may be used to remove the heat directly, or the heat could be transferred to a coolant, usually circulating water. The water carrying the heat is then circulated through a chiller or any heat transfer system. However, these arrangements depend on the system size and configuration, and can be expensive, complex, and noisy.

The UltraTEC series of thermoelectric modules offers excellent heat pump density, and allows precise temperature control. In fact, under steady state conditions, temperatures can remain within ±0.01°C. As these thermoelectric modules offer solid-state operation, these cooling solutions do not produce noise or vibrations. Moreover, they are available in multiple configurations, making them simple to implement.

Any laser system needs to be accurate and repeatable. Stability of the laser system is highly dependent on balanced, controlled cooling. The advantage of using UltraTEC thermoelectric modules for cooling is they can deliver highly reliable cooling solutions under conditions where the laser is in continuous use and even when cycling at high powers.

Laird assembles UltraTEC thermoelectric modules from Bismuth Telluride semiconductor materials. They use aluminum oxide ceramics, which are thermally conductive. This makes the UltraTEC thermoelectric modules capable of carrying high currents that are necessary for large heat-pumping applications. For instance, with Qmax rating of 340.6 W at 25°C, these thermoelectric modules can operate continuously up to 80°. This adequately ensures that the laser system will never overheat when being cooled by the high heat pump density UltraTEC series of thermoelectric modules. These modules are RoHS compliant and DC operated.