Over the past century there has been a dramatic increase in the demand for float glass in many fields of industry. Usually, 10 to 30% of produced float glass is coated with various coatings for different purposes. As a consequence quality control of the coatings is one of the most current issues during the process of float glass manufacturing. In this work we describe a system designed for the online control of reflectivity, transmittance and color coordinates of the coatings during the glass production process. The working principle of the system is based on the measurement of the spectral characteristics of reflectivity and transmittance of coatings within the 400-700 nm spectrophotometer spectral range during the online coating process. The measurement unit consists of two microspectrometers (one for the measurements of the spectral characteristics of the reference source, and the other for the measurements of the reflectance spectrum), illumination head (consisting of one white 1W LED and collimating lenses), stabilized power supply, microprocessor and 18 bits precision ADC. The use of the reference channel allows us to stabilize the intensity of the incident light up to 10-4 level. The repeatability of the measurement of reflectivity coefficient in laboratory conditions was in range of ± 0.001. However, in the measurements in the factory environment, due to the vibration of the glass ribbon on the conveyer, the measurement reproducibility was about ± 0.005.

Date Published: 13 May 2013
PDF: 7 pages
Proc. SPIE 8788, Optical Measurement Systems for Industrial Inspection VIII, 878835 (13 May 2013); doi: 10.1117/12.2020763

Published in SPIE Proceedings Vol. 8788:
Optical Measurement Systems for Industrial Inspection VIII
Peter H. Lehmann; Wolfgang Osten; Armando Albertazzi, Editor(s)