• High Precision
• Fast Response Time
• Excellent Detection of Streaks and Gaps
• Rugged Solid State Design
• Minimized Base Material Sensitivity
• Long Lamp Lifetime, Easily Replaced

Description

The NDC Model 120 affords simple, reproducible and reliable measurement of ultra-light aqueous, solvent and thermoplastic coatings. The NDC Ultra-Violet Fluorescence (UVF) sensor operates by adding a minute amount (0.01 - .05% typical) of a fluorescent tag to the emulsion, solution or thermoplastic coating. The sensor measures the amount of the tag that is present after the coating is applied. Measurement is made in a backscatter mode from the coated side of the web. Coatings can be measured wet or dry. Typical tags have a fluorescence efficiency of 95% when exposed to ultra-violet radiation. Excitation is accomplished by a bright, efficient and safe, non-nuclear source. Data is rapidly sampled and converted to display of engineering units such as g/m2.

Theory of Operation

Light emitted by a mercury lamp is filtered and collimated. The light passes through a beam splitter and lens, and then onto the product to stimulate fluorescence. Fluorescent light emitted by the product is collected by the same lens and re-collimated. This light passes through a beam splitter and filter tuned to the primary emission wavelength of the particular tag used and is focused onto the signal detector. A small portion of the ultraviolet light from the mercury lamp passes through a beam splitter and is separately detected by a reference detector to compensate for lamp intensity fluctuations. The reference and sample signals are combined, filtered to remove the effects of ambient light, and processed to produce a sample coat weight.