Since lasers are so precise, they have a lot of different parts to ensure they work correctly. If one component is off, the entire laser will function improperly, which can lead to disastrous results. Temperature sensors help ensure the laser is working properly. Continue reading to learn about the different temperature sensor types and their different uses.
What Is a Temperature Sensor?
Before understanding the different laser temperature sensors, you must know their roles in a laser system. When you use a laser, you want to eliminate outside variables as much as possible. You must ensure that the laser is stable and accurate, and one variable that is important to control is temperature.
Some lasers must charge for around 30 minutes to reach their full power. Others don’t need to charge for this long, but whether the laser is on for a second or an hour, you will see some temperature changes. Lasers are light amplified by the emission of radiation, and while they are on, they build up heat. This heat can interfere with the laser itself and some of the peripheral equipment that keeps the laser functional and stable in the first place.
As the temperature builds or, in some cases, cools down, the laser light quality can change, affecting the stability of the laser. If the laser is unstable, it will not properly fulfill its purpose. Data points will be incorrect, cuts will not be clean, and data won’t be transferred. All of this can compound, resulting in even more problems. Temperature changes can also potentially damage the laser itself.
Temperature management is critical in laser systems, which is why people have developed temperature controllers that can address temperature variances as they arise.
What Is a Temperature Controller?
A temperature controller is a critical part of any laser system because it can recognize and address temperature changes quickly. Manufacturers designed them to sense when temperatures go above or below a designated temperature range and respond appropriately. Temperature controllers can heat or cool the laser diode to the right temperature window. Within the laser diode is a Thermo-Electric Cooler (TEC), a device that appropriately heats or cools the system when a positive or negative current is applied.
However, before the temperature controller and TEC can do that, the controller must sense temperature changes in the first place. It does this with temperature sensors and depending on the type of laser and general application, there are multiple sensor options to choose from. The most common temperature sensors you can find are:
- Thermistors
- Thermocouples
- Platinum Resistive Temperature Devices (RTDs)
- IC Sensors
Each has advantages and disadvantages, but the best one ultimately depends on the application requirements. Some are more versatile than others, while some are more finely tuned and can recognize even the smallest temperature changes.
Pros and Cons of Thermistors
Some of the most common temperature sensors that you can find for many different applications are thermistors, which are very often used as laser temperature sensors. They are relatively small and have a fast response time, making them typically very effective at sensing temperature changes and adjusting before they spiral out of control. It is a nonlinear resistance device, meaning that it requires a small and accurate current source to operate.
These thermistors work because the temperature change leads to resistance change. The thermistor uses the Steinhart-Hart equation to convert the resistance to temperature as the resistance drops or rises because of the change in temperature. Thermistors have large resistance changes, meaning that they can measure even the smallest temperature changes. Depending on the kind of thermistor material, you’ll also see minimal drift compared to other sensors.
Their operating range is generally between –25°C to +125°C, which is useful for most applications but not as wide as some other temperature sensors. Even with this smaller range, people use thermistors for multiple applications, like safety equipment, thermometers, and laser temperature controllers.
Pros and Cons of Thermocouples
While thermistors have a smaller operating range, thermocouples can measure temperature changes in a significantly larger range, about −180°C to +2,320°C. While they can measure changes in this range, they have some drawbacks. Thermocouples have poorer stability, and their results are less repeatable. Their range is great for larger applications, and their response time is quick, but they can fail to register smaller temperature changes. They are one of the more affordable temperature sensor options, making them a great choice for industrial applications.
Pros and Cons of Platinum Resistive Temperature Devices (RTDs)
Part of what makes RTDs so unique compared to other temperature sensors is they are incredibly stable and accurate. You won’t experience too much drift over time, and you can rest assured that it will notice any temperature changes quickly and respond to them accordingly. However, they have relatively small resistance changes, so they will struggle to measure small temperature changes. Additionally, RTDs are more expensive than some other temperature sensor options.
With all that said, RTDs are a great option. They can spot changes over a wide range, from –250°C to 750°C, and are incredibly stable, as we mentioned. These factors make them great for long-term applications that need accurate temperature control.
Pros and Cons of IC Sensors
Whereas thermocouples, RTDs, and thermistors are nonlinear, IC sensors are linear, meaning you can easily convert their output into °C. Their linearity is a pro, but they are not as accurate as some of their counterparts. They can also be quite slow at times, making them not the best choice for laser applications that need to make temperature adjustments as soon as possible. These sensors also don’t have the biggest operating range, going from about –55°C to 150°C.
While IC sensors have some drawbacks, they also have some benefits compared to other sensors. They’re incredibly small and have low power consumption. These benefits make them great for applications like fitness tracking and computing systems.
Each different temperature sensor has a specific use, but they’re all important for ensuring that your laser system works correctly. Without these sensors, it would be hard to detect if something was amiss with the temperature of your laser system and needed to be heated or cooled. Here at Arroyo Instruments, we are one of the best temperature controller manufacturers, and we can ensure that our temperature controllers can detect temperature changes and correct them. You will surely have a consistent and efficient laser system when you work with us!
