Patent ID: 6859285

Claim:
An optical system for producing an image of the surface of an object, said object having a characteristic, temperature-dependent, dominant, self-emitted EMR spectrum, comprising: an EMR source for projecting electromagnetic radiation toward said object; an EMR detector for selectively detecting a spectrum component of said projected EMR, said component being reflected by the surface of said object and being directed toward said EMR detector; an airflow controller to provide airflow at a preselected temperature around said hot object to decrease a temperature gradient to remove air density distortion; and wherein said projected electromagnetic radiation has a wavelength which is selected as a function of object temperature and material, said reflected component of said projected EMR has said wavelength that is different than said self-emitted, dominant EMR spectrum such that the reflected component can be distinguished from said self-emitted EMR based on wavelength and wherein said optical system further includes an interference filter in association with said EMR detector configured to pass said wavelength and block self-emitted EMR.