In-process monitoring in laser solidification apparatus

A laser solidification apparatus for building objects by layerwise solidification of material, the laser solidification apparatus comprising:—

• a build platform for supporting the object and a material bed, an optical module comprising a movable guiding element for directing the laser beam to solidify material of the material bed;
• a detector module comprising a sensor for detecting radiation emitted from the material bed and transmitted to the sensor by the movable guiding element of the optical module, the detector module removably mounted to the optical module;
• and
• a controller comprising an interface arranged to be releasably coupled to an electronic output of the detector module such that the controller can receive sensor signals from the sensor of the detector module,
• wherein the controller is arranged to form data packets comprising control or measurement data sent to or generated by the optical module and sensor data based upon the sensor signals received from the detector module.