1. Presented by: Les Jenson Chief Engineer Beta LaserMike
2011 AIMCAL Technical Conference
Non-Contact, Laser-Based Technology for Accurately Measuring the Length and Speed of Product in Web Coating and Lamination
Presented by: Stuart Manser, Beta LaserMike
Presented by:
Les Jenson
Chief Engineer
Beta LaserMike
BETA LaserMike

2. Introduction Technology of a Non-Contact Length and Speed gauge
Describe how it works
Three applications examples:
Coating and Lamination Control
Continuous Length
Stretch and Draw

3. Traditional Length & Speed Measurements
Accomplished by using a roller that contacts the material being measured
The material turns the roller as the material moves
An encoder or tachometer is attached to the roller
Generates pulses as the wheel or roller rotates
Relies on friction between the material and roller

4. Disadvantages Tachometers/Encoders
Error caused by slippage
Dependent on friction
Wheel pressure
Product surface
Lubricant on surface
Recalibration
Diameter change because of wear
Diameter change because of build-up
Maintenance
Bearings and other mechanical parts wear out

5. LaserSpeed History LaserSpeed technology was developed in 1984
Aluminum/Steel Mills
Small integrated gauge developed in 2001
Smaller
Cheaper
Easy to Install
High Accuracy – 0.05%

6. System Concept FPGA- Signal processing PCB
Laser diode assembly with temperature control
Proprietary beams steering optics and receiving optics
Measuring region

7. Non-Contact Gauge Technology

8. Non-Contact Gauge Technology
Two laser beams cross at an angle 2K
K bisects the two laser beams
Constructive and Destructive Interference cause a Fringe Pattern
The Fringe Pattern consists of light (constructive) and dark (destructive) stripes

9. Fringe Pattern Expanded
Constructive Interference occurs when two laser beams are in phase and add together to equal the original laser density - light stripe
Destructive Interference occurs when two laser beams are out of phase and the two laser beams cancel each other out - dark stripe

10. Fringe Pattern Generation
Fringe Pattern looks like an elongated football
Measuring region (Depth of Field) is where the fringe pattern exist
Project this fringe pattern on the surface of the product to be measured

11. Laser Doppler Velocimetry (LDV) Theory
Fringe direction

12. No Calibration Required
Wave length of the laser is fixed and constant
Laser diode based system
Laser diode is temperature controlled
Crossing angle is created optically
No moving parts in optics package
Crossing angle is permanently fixed
Fringe Spacing ‘d’ is fixed and cannot change

13. No Calibration Required
Frequency measurement uses an all Digital Signal Processor
Autocorrelation algorithm
High measurement rate
High measurement accuracy
High measurement repeatability
Signal processor is all digital and has no drift or measurement error

14. No Calibration Required
Length is achieved by numerically integrating the speed
Permanently calibrated with very high accuracy

15. Non-Contact Gauge Block Diagram - Dual-Beam Laser Interferometer
Diode Laser
Acusto-Optical Modulator
Product
Optical Beam Splitter
Photo -Detector
Received Light
Receiving Lens (15mm)
Fringe Direction
Measurement Region

16. Coating and Lamination Control Application
Manufactures label products
Depends on accuracy of line’s drive speed and contact encoder to:
Apply adhesive and easy release coatings to backing
Apply varnishes to face of label
Control speed of two or more materials during lamination of clear material to printed face stock
Measures product length to apply exact quantity of coatings and lamination

17. Problem Inaccurate length and speed measurements
2% error
Slippage due to texture, slick coatings, lubricants, etc.
Contact method relies on wheel circumference and # of rotations
Contact measurement wheel:
Rides on product
Builds-up debris or wears down
Requires recalibration

18. Scrap Cost Calculation
2% length and speed inaccuracy
20,000 foot roll
400 feet of uncertainty
Each roll costs a significant amount in unnecessary expense
Scrap = roll length x material cost/ft x contact encoder accuracy (2%)

19. Solution
Install non-contact laser gauge at specific measurement points on the line
Control length and speed of lamination line and coating application
+/- 0.05% speed accuracy
Instead of 400 foot per every 20,000 feet of uncertainty
Lowers error to a max of 10 ft on a 20,000 foot roll
Coating Control
Lamination Control

20. Continuous Length Application
Manufactures diapers, pads, liners and pull-on style disposable underwear
Slitting and cut-to-length requirements

21. Problem Lubricants caused slippage errors – 2.5%
Slippage errors always make the product length long
2.5% slippage error on a 1000 foot makes the actual length 1025 foot
Give away 25 foot for every 1000 foot produced

22. Scrap Cost Calculation
Manufacture produces between $2 to $4M of product on this line per year
Over length error of 2.0% cost between $40,000 and $80,000/year/machine

23. Solution
Non-contact laser gauge was installed on in-feed side of parent roll
Non-contact gauge has no slippage errors
Potential saving of $40,000 to 80,000/Year
Reduced maintenance costs
No recalibration
No moving parts to wear out

24. Stretch and Draw Application
Manufacturers require:
Draw down of thin sheet to consistent thickness
Draw and drive rollers pull product down at same speed
Draw down to specific controlled thickness with minimal variance and breakage

25. Problem
Drive speeds and contact encoders do not provide accurate measurements
Tension problems, product composition, and texture cause slippage errors
Slippage error - 1% to 2%
Wheel wear, dirt buildup causes calibration errors
Calibration is directly proportional to the circumference of the wheel
Down time for recalibration

26. Solution
Install non-contact laser gauge at each critical measurement point along the line
Non-contact laser gauge directly measures product
Slippage is not a problem
+/-0.05% accuracy provides reliable, precise stretch and draw measurements
Eliminates any measurement guesswork and uncertainty

27. Summary
Non-Contact Laser Gauge Advantages
No slippage error - optical system and does not contact the product
Permanently calibrated – Laser Interferometer Optical system
No moving parts to wear out
Accuracy: +/-0.05%
Repeatability: +/-0.02%

28. Summary Continued Complete System in one small rugged package
Sensor
Processor
I/O
Power Supply
24 VDC operation
IP67 protection
Built-in water cooling ports
26.25 X X 10.5 cm
2.54 Kilograms

29. Thank You -- Questions