Method for calibrating a sensor for monitoring a melt pool in an additive manufacturing machine

A method for calibrating a monitoring sensor for a melt pool in a melt pool monitoring system of an additive manufacturing machine, the method comprising at least the following steps:

• measuring and recording a value of a signal transmitted by the monitoring sensor when the monitoring sensor is not exposed to a reference radiation;
• exposing the monitoring sensor to the reference radiation;
• measuring and recording a value of the signal transmitted by the monitoring sensor when the monitoring sensor is exposed to the reference radiation;
• calculating a correction coefficient for the monitoring sensor from a reference value associated with the reference radiation and the values of the signals transmitted by the monitoring sensor when the monitoring sensor is not subjected to the reference radiation and when the monitoring sensor is subjected to the reference radiation;
• and
• recording in a correction table the correction coefficient for the monitoring sensor and the value of the signal transmitted by the monitoring sensor when the monitoring sensor is not exposed to the reference radiation,
• wherein an electronic gain of the monitoring sensor is adjustable, and the electronic gain is adjusted to a predefined value before the steps of measuring and recording the values of the signals transmitted by the monitoring sensor.