Emissivity correction apparatus and method

Apparatus for measuring the emissivity of a remote object that is within a chamber including a boundary wall of quartz and that is heated to elevated temperatures by radiation supplied thereto through the quartz boundary wall, the apparatus comprising:

• first detection means disposed to detect through the quartz boundary wall the spectral radiation emanating from a selected location on the remote object at elevated temperature for generating output signals representative of the detected radiation within a selected waveband;
• source means of radiation disposed to supply radiation of selected intensity within the selected waveband through the quartz boundary wall to the selected location on the object;
• second detection means disposed for measuring the intensity of the radiation from the source means reflected from the selected location on the object;
• and
• circuit means coupled to receive the output signals from said first and second detection means for producing therefrom an output that is representative of the emissivity at elevated temperature of the remote object.