Laser Molten Metal Level Control Posted in: Fill Level Measurement, Updates – Tags: , ,

Over the years, the metal industry has developed into a key focus for Acuity Laser, with extensive experience with integrated steel mills and foundries. Experience gained from several applications in the metals industry has given us a comprehensive understanding of the potential issues when installing our sensors into these difficult environments.

A common Acuity sensor used in the metal industry is our AS2100 Accurate Distance Sensor. In particular, a few of our customers are using the AS2100 to measure and control the level of molten metal in a furnace. The AS2100 is often selected for this application because it performs better on hot targets due to the sensor’s phase mixing technology. The sensor also boosts an impressive linearity of +/- 1 mm over the full range of 100 meters and can measure fill levels at speeds up to 250 Hz. Due to its high performing capability, measurement technology, and standard interfaces (RS232/RS422/RS485 digital outputs and 4-20 mA current output), as well as ethernet/IP communication, it is easily the preferred sensor for this application.

When designing our AS2100 sensor into applications like the monitor molten level control, it is important to consider a few factors related to heat.

AS2100 cooling enclosure front

AS2100 cooling enclosure front

The first challenge is the sensor’s measurement of the hot, glowing molten metal material. Although sometimes a challenge, using the AS2100 for measurements on these types of surfaces is possible. In fact, the AS2100 sensor has had a lot of success in measuring high temperature targets largely due to the sensor’s measurement technology and because it contains a filter glass integrated directly in the sensor that reduces disturbances outside of the laser’s wavelength. However, the higher the target’s temperature is, the higher the disturbance. For some targets, the disturbance is too high, and the sensor’s detector becomes swamped and unable to take a measurement. To further help reduce disturbances, an additional bandpass filter glass can be installed in front of the sensor optics.

The second heat related challenge is the ambient temperature the sensor is installed into – in this case, the furnace. The AS2100 can accurately measure from a long distance away, but when installing inside a furnace, it is often hard to find an area to install the sensors to protect it from the harsh, hot environment. Protecting the sensor from the ambient heat is critical for the sensor to operate and to maintain its implied lifespan. Without the option to install the sensor at a safe distance away, additional cooling is needed for this sensor to work in this environment.

AS2100 cooling enclosure rear

AS2100 cooling enclosure rear

To deal with these heat related challenges, Acuity engineers have designed an AS2100 cooling enclosure with a built-in bandpass filter option. The cooled housing enables the sensor to be protected from the hot ambient temperature and the bandpass filter options allows the sensor to perform reliable, accurate measurements on the molten metal. The combination of the sensor, the cooled housing, and the additional bandpass filter enables the ability for accurate level control despite the difficult challenges this application presents.

To learn more about the AS2100 or the cooled housing developed by the Acuity team, please reach out to us at

Related Products

AS2100 Accurate Distance Sensor

The AS2100 is a highly accurate laser distance sensor that is designed to work well outdoors, in bright lights, and even on difficult targets such as hot or dark surfaces. With the ability to take accurate measurements (± 1 mm) from distances up to 500 meters away, and a measurement frequency of up to 250 Hz, it is the perfect laser for a wide range of applications.