Optical In-line Control of Web Coating Processes with UV-VIS-NIR Spectroscopy. AIMCAL Europe Web Coating Conference Peter Lamparter

Transcription

1 Optical In-line Control of Web Coating Processes with UV-VIS-NIR Spectroscopy AIMCAL Europe Web Coating Conference Peter Lamparter

2 Optical In-line Control of Web Coating Processes with UV-VIS-NIR Spectroscopy 1 Why Inline Process Monitoring? 2 Photo Diode Array Technology 3 Measured Spectra and Calculated Values 4 Measurement Geometries 5 Requirements and Challenges of Inline Monitoring 6 Conclusion

3 Agenda 1 Why Inline Process Monitoring? 2 Photo Diode Array Technology 3 Measured Spectra and Calculated Values 4 Measurement Geometries 5 Requirements and Challenges of Inline Monitoring 6 Conclusion

4 Benefits of optical inline control Inline Monitoring Process- Optimization Improved Yield Improved Quality Improved Profitability

5 Optical Inline Monitoring with UV-VIS-NIR Spectroscopy Spectral Transmission and Reflection in a wavelength range from 190nm to 2.200nm Colorvalues, Layerthicknesses, Haze 5

6 Agenda 1 Why Inline Process Monitoring? 2 Photodiode Array Technology 3 Measured Spectra and Calculated Values 4 Examples 5 Requirements and Challenges 6 Conclusion

7 Schematic: Diode Array Spectrometer; Transmission Dispersive device: Grating SMA Fiber Connector Sample Light source Spectrometer Body Photo Diode Array Cross section converter / Slit

8 Schematic: Diode Array Spectrometer; Reflectionion Dispersive device: Grating SMA Fiber Connector Sample Light source Spectrometer Body Photo Diode Array Cross section converter / Slit

9 Gratings Spektrometer Moduls Spectrometer in Production Line

10 Agenda 1 Why Inline Process Monitoring? 2 Photo Diode Array Technology 3 Measured Spectra and Calculated Values 4 Measurement Geometries 5 Requirements and Challenges of Inline Monitoring 6 Conclusion

11 Color Measurement What is light? Light belongs to electromagnetic waves. The human eye captures visible light in the range between about 380 nm and approx nm. The eye captures three different color stimuli: blue, green and red. The color impression is achieved by addition of these three stimuli in the brain. Any color can be composed by adding red, green and blue. Radio waves IR 380 nm 750 nm (visible light) UV X-rays Cosmic rays

12 Color Measurement Color impression depends on three interrelated factors: Light source E.g. daylight or filament lamp, with different intensities of their individual spectral components. Sample The composition defines the components of reflection, absorption and refraction. Light source Observer Observer Different sensitivities of the three lightsensitive receptors on the retina convey different color impressions. Sample

13 Color Measurement Standard geometries Light source Observer 0º/45 45/0º Light source Observer 0º/d d/0º

14 Color Measurement In addition to the CIE color system, it is mostly the L*, a*, b*-system developed by Judd and Hunter, standardized in 1976 and also based on sensitivity. The L*-value indicates the position of the bright/dark axis, the a*-value the position of the red/green axis and the b*-value the position of the blue/yellow axis. The L*, a*, b*-coordinates are directly related to the standard color values X, Y and Z.

15 Layerthickness Measurement White light interference By illuminating samples with white light, interference spectrums are created as a function of the geometric layer thickness and refraction index due to the superposition of reflection spectrums caused by the upper and lower sides of the coating. L1 D = Geometrical thickness L1= Reflection on the upper side of coating L2= Reflection on the substrat Phase shift between L1 and L2 D L2 Coating Interference Substrat

16 Layerthickness Measurement Interference of a single layer with 10 µm thickness

17 Layerthickness Measurement Peak after Fourier transformation Result is the optical thickness of the coating

18 Layerthickness Measurement Interference of two coatings with 2 µm and 15 µm thickness

19 Layerthickness Measurement 3 Peaks after Fourier transformation Result is the optical thickness of both coatings

20 Layerthickness Measurement? Model for optical constants: Tauc Lorentz, OJL, Drude, extended Drude, Kim, combinations, const., New Model Information about the Layerstack Fit - Strategy Inline Prediction of Layerthickness

21 Agenda 1 Why Inline Process Monitoring? 2 Photo Diode Array Technology 3 Measured Spectra and Calculated Values 4 Measurement Geometries 5 Requirements and Challenges of Inline Monitoring 6 Conclusion

22 OPTOPLEX in a glass coating line OPTOPLEX Q NG Quality Control OPTOPLEX III P Process Control

23 OPTOPLEX Q 2 T NG

24 OPTOPLEX III P Configuration with Parallel optics, Transmission

25 OPTOPLEX III P Configuration with Parallel optics and illumination sphere; Transmission

26 OPTOPLEX III P Configuration with Parallel optics and Reflectance Measuring Head OFR d/8

27 OPTOPLEX WEB - Transmission

28 OPTOPLEX WEB Transmission/ Reflection

29 Agenda 1 Why Inline Process Monitoring? 2 Photo Diode Array Technology 3 Measured Spectra and Calculated Values 4 Measurement Geometries 5 Requirements and Challenges of Inline Monitoring 6 Conclusion

30 Requirements for Optical Inline Measurement Systems Non destructive / Contact-free Shortterm ROI Easy Integration in production line User Maintenance and Service Friendliness High Reliability / Robustness/ Stability High Accuracy / Precision High Performance

31 Spectrometer Module Design Principles Fiber cross-section converter as optical input SMA connector Holographically recorded and blazed imaging grating Photodiode Read-out Robust housing, no moving parts Benefits Highly reliable Permanently calibrated No moving parts Wide dynamic range Robust Fiber optic input Diode array equipped

32 Reliability / Robustness Example for a harsh environment: Inline Spectroscopy on a Combine Harvester

33 Accuracy/ Precision Not precise and not accurate Precise, but not accurate Accurate, but not precise Precise and accurate Influenced by Tolerances of: - Reference Methode - Calibration Standards - Measurement System

34 Optoplex WEB Production Line Integration High Measurement Frequency Configurable Measurement Parameters Configurable Multi-graph View - showing spectra, trends, tables, Result evaluation against scalar & spectral tolerances OPC DA 2.0 output of spectra, results, parameters, status information Controlling of measurements via OPC DA 2.0 Result and spectra export in txt format Time controlled measurements External Trigger Automatic and Manual reference measurements Historical Data Retrieval

35 Challenges Distance- /Angle variations Calibration (Material, Methode ) Waviness of Substrate Adjustment of the Measurement Heads Ambient Reflections / Ambient Light Space/ Footprint Contamination

36 Agenda 1 Why Inline Process Monitoring? 2 Photo Diode Array Technology 3 Measured Spectra and Calculated Values 4 Measurement Geometries 5 Requirements and Challenges of Inline Monitoring 6 Conclusion

37 Conclusion Some challenges concerning integration, but Inline measurement technology can provide Lab-values Coater design has to be considered and/or adjusted Most successful when integration is accomplished in partnership between equipment manufacturer or owner and measurement system provider