In-Situ Color Monitoring

The RTG-Infinity Series product incorporates patent-pending technology to monitor the Red, Green, and Blue color components with an overlapping sensor design that guarantees every spot across the film is monitored.  The image below is a 16” (41cm) wide sensor array, with overlapping sensors, partially covered by a colored film.   The first chart indicates the percent transmission of each color component.  The subsequent charts depict CIE XYZ and L*a*b* data.


CIE XYZ representation:


L*a*b* Color representation:


The advanced settings for the L&M RTGOM-Infinity software allows configuration of the matrix transform between the sensed RGB data and the CIE XYZ values that also drive the L*a*b* data.  This allows better matching with existing in-house systems and color spaces.


Window and Specialty Films

Modern window films require varying combinations of specific ultraviolet (UV), visible, and infrared (UR) response.  In addition to monitoring the critical RGB components, The RTG-Infinity series can be custom designed to add other wavelength bands for monitoring.  A system can, for example, monitor specific UV, Visible, and IR bands to provide full-width coverage for all critical wavelength bands.  The same techniques can be used for monitoring specialty films that have a handful of critical wavelength bands.  Even when a more expensive spectrometer-based system is used during initial deposition, the RTG-Infinity technology can be used for process checks during down-stream converting operations.

Rugged by Design

When you hold an L&M Instruments light source or detection module in your hands, you immediately know you have made the right product decision for deployment into your harsh environment.  All devices are built using heavy-weight, rugged anodized aluminum housings.  Optical components are sealed with vacuum-friendly compression mounts.  High-temperature electronics are sealed with a variety of techniques to resist dust and humidity.  System design minimizes power and cabling requirements, including “head-less” configurations for precision optical feedback without the need for a computer and monitor.

“Pitch Perfect”

Many optical density monitoring solutions in the field today monitor at a fixed transverse-direction (TD) interval or “pitch”.  This pitch usually matches the spacing of the evaporative sources, giving an OD reading for the location directly above each evaporative source.  Over time manufacturers have added more sensors, at a smaller pitch across the TD, to detect banding and other anomalies.  In some systems a single optical density sensor is installed and moved across the TD during the deposition process.  This provides a theoretically zero pitch across the transverse direction, trading off machine direction (MD) resolution, as the actual sensed area over the length and width of the substrate represents a serpentine or zigzag pattern.  While the L&M technology is deployed in all such configurations, the new RTG-Infinity series of products is designed to eliminate the tradeoff between TD and MD resolution.  The Infinity series provides Patent-Pending overlapping sensor technology to simultaneously detect the OD across the entire width of the substrate, with no moving parts.

Wavelength Selection

One of the key factors when monitoring optical density or percent transmission is the actual wavelength, or wavelengths, used for detection.  Near-IR monitoring, typically in the 900 to 1000nm range, is common for metal deposition monitoring.  The wavelength has good optical characteristics relative to the end-product features.  At times, however, it is desirable to match an in-house standard.  Because such standards are more “visual” in nature, they typically have a more human visual or, sometimes, “orthochromatic” response.  The L&M products provide a variety of options from the ultraviolet to the mid-infrared.  This not only allows better matching to in-house visual-spectrum standards, but also allows the monitoring of custom properties that may be a result of a few wavelength bands.  Some material layers, for example,  can be effectively monitored based on the ratio of two wavelength bands.  In such cases, two RTGOM modules can be configured with two different wavelength bands.  This can produce a system with better sensitivity and stability than other spectrometer-based solutions.