This unique industrial application uses 3 optical channels to monitor silver film deposition on a moving roll of plastic using transmission and reflectance.  One channel is used to perform lamp drift compensation for the 2 other measurement channels. One channel is setup with a silver reference reflectance profile with a reflectance probe positioned over the web sample.  The 2nd measurement channel is setup to continuously measure transmittance just below the web sample where the probe illuminates.   The "web" consists of a continuous sheet of plastic that is on a conveyor that is moving out of a silver coating deposition chamber.
 

The objective of the continuous monitor is to spot defects in the silver coating that is being applied to the plastic sheet.  The instrument computer receives input from the moving web tachometers that provide precise positioning information to the SpectraWiz software.  The software is recording to disk the web position in feet, the reflectance value, and the transmission value for the entire process.  Additionally the SpectraWiz software provides real-time displays and alarms (when triggered) that watch pre-set limit values for the 2 measurement channels.  Simple operator key-press functions allow detailed viewing when problems occur with the coated material on the web.