Sometimes conventional thermometer can’t be used to measure high temperature in steel manufacture. It’s not safe for human stand up near to melted steel. Thus, infrared thermometer is used for that situation. If you want make your own infrared thermometer, you can follow this infrared thermometer project.
This contactless thermometer is built using MLX90614 sensor and Arduino. The device is able to measure temperature with range from -70 to 380 degree Celsius.