Patent ID: 7929140

Claim:
A process monitoring system for determining a spectral response of a process material, the system comprising: a drum for containing a process material, the process material being processed within the drum, the drum comprising a window element; a semiconductor tunable source for generating an optical signal that is wavelength tuned over a scan band; and an optical probe, secured on an outside of the drum, for conveying the optical signal to the process material, through the window element, and detecting the optical signal after diffuse reflection, received through the window element, from the process material to yield the spectral response of the process material, the optical probe for expanding a beam of the optical signal to a diameter of greater than 10 millimeters prior to the diffuse reflection from the process material, wherein the optical probe comprises a projection lens system that expands the beam of the optical signal from the tunable source to the diameter of greater than 10 millimeters using a series of projections lenses that expand and improve a collimation of the beam of the optical signal.