A laser processing head for processing a workpiece by means of a laser beam, comprising: - a housing through which a beam path for the laser beam is guided, and which has a focusing optics for focusing the laser beam onto a joint of the workpiece to be processed, - a light cutting device fitted on the housing having a light source for generating on the workpiece a light line which cuts a location to be joined at a predetermined distance (d) from the joint, - a camera with an optical bandpass filter arranged in an observation beam path in front of the camera, the light source having an at least local emission maximum in the wavelength passband of the bandpass filter, and the optical bandpass filter being configured so that the laser beam is not transmitted, and the camera imaging the light line at the location to be joined as well as the portion transmitted by the bandpass filter of the process light of a melt pool, produced by the laser beam impinging on the workpiece to be processed, at the joint at regular time intervals, and - a processing unit with a memory for receiving the recorded image data from the camera, which is designed -- to determine, by image processing of the received image data, the intersection point of the light line with the location to be joined, -- to store the intersection points between light line and location to be joined as target trajectory in the memory, and -- to determine a minimum distance between the stored target trajectory and the current melt pool midpoint, characterized in that the processing unit is configured to determine the midpoint of the melt pool at the joint by image processing. - a housing through which a beam path for the laser beam is guided, and which has a focusing optics for focusing the laser beam onto a joint of the workpiece to be processed, - a light cutting device fitted on the housing having a light source for generating on the workpiece a light line which cuts a location to be joined at a predetermined distance (d) from the joint, - a camera with an optical bandpass filter arranged in an observation beam path in front of the camera, the light source having an at least local emission maximum in the wavelength passband of the bandpass filter, and the optical bandpass filter being configured so that the laser beam is not transmitted, and the camera imaging the light line at the location to be joined as well as the portion transmitted by the bandpass filter of the process light of a melt pool, produced by the laser beam impinging on the workpiece to be processed, at the joint at regular time intervals, and - a processing unit with a memory for receiving the recorded image data from the camera, which is designed -- to determine, by image processing of the received image data, the intersection point of the light line with the location to be joined, -- to store the intersection points between light line and location to be joined as target trajectory in the memory, and -- to determine a minimum distance between the stored target trajectory and the current melt pool midpoint, -- to determine, by image processing of the received image data, the intersection point of the light line with the location to be joined, -- to store the intersection points between light line and location to be joined as target trajectory in the memory, and -- to determine a minimum distance between the stored target trajectory and the current melt pool midpoint,