Pyrometer including an emissivity meter

A laser processing apparatus comprising a radiation source supplying a processing beam,

• an optical head for directly directing the processing beam onto an object surface, and
• a pyrometer for measuring thermal radiation and emissivity for both diffusely and specularly reflecting surfaces of an object, said pyrometer further comprising:
• a thermal radiation detector;
• an optical system connected to the thermal radiation detector for concentrating thermal radiation originating from an object surface area on the detector;
• an emissivity meter connected to the optical system, the meter further comprising a radiation source supplying measuring radiation and a measuring radiation detector for converting the measuring radiation reflected by the object surface into an electrical signal;
• an optical integrator adjacent to the object surface area arranged in the radiation path of the measuring radiation between the radiation source and the measuring radiation detector, wherein the radiation source extends to an aperture of the optical integrator and diffusely irradiates the object surface, and
• a shield connected to the optical integrator for preventing measuring radiation from irradiating the object surface area directly.

A method of monitoring and controlling the process of heating a surface, in which the temperature of the surface is measured by a pyrometer comprising:

• a thermal radiation detector;
• an optical system connected to the thermal radiation detector for concentrating thermal radiation originating from an object surface area on the detector;
• an emissivity meter connected to the optical system, the meter further comprising a radiation source supplying measuring radiation and a measuring radiation detector for converting the measuring radiation reflected by the object surface into an electrical signal;
• an optical integrator adjacent to the object surface area arranged in the radiation path of the measuring radiation between the radiation source and the measuring radiation detector wherein the radiation source extends to an aperture of the optical integrator and diffusely irradiates the object surface;
• and
• a shield connected to the optical integrator for preventing measuring radiation from irradiating the object surface area directly,
• said temperature being subsequently used for monitoring and controlling the heating process.