Precision Scan-Imaging

Mittuniversitetet

Precision Scan-Imaging

For Paperboard Quality Inspection utilizing X-ray Fluorescence

Industry – University project

Calcium content in paperboard

Tommy Nordin Salim Reza Christer Fröjdh Börje Norlin

MID SWEDEN UNIVERSITY

Mittuniversitetet

Paper coating quality

• Outline

• Motivation

• Description of Industrial interest and State of the Art measurements

• XRF Measurements, MIUN & MoRe

• Transmission measurements

• Conclusions and visions

• Challenge

• To understand internal “state of the art” quality measurements

• Every company has different views on quality.

• Show that an X-ray method is consistent with existing methods

• Gain for companies

• MoRe Research offers analysis service, including XRF

• Future vision

• An online system (i.e. Timepix 3 of Medipix 4) could be used to control and optimize the whole production line

2017-07-03

Precision Scan-Imaging for Paperboard

Quality Inspection utilizing X-ray Fluorescence 3

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“The outside counts”

The paperboard printing quality

depends on the coating homogenity

Packaging must exude luxury and live up

to the brand (Martin Sutnar, Läderach)

2017-07-03 Precision Scan-Imaging for Paperboard


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Quality measurements

• Paperboard

• Cellulose fibers [C6H10O5]

• Coating [CaCO3]

• Coating on one or both sides

• The coating gives a smooth surface suitable for high quality printing

• State of the art quality measurement –

The Burnout method

• Acid and heat ”burns” the cellulose

• Thin coating will appear as dark areas on the burnt sample.



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Paper s

am

ple

XRF measurement setup

source

Slit

Spectrometer



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XRF Spectrum

Ca Ka

3.69 kev

Ca Kb

Fe Ka

2.96

&

3.19

?

Pb La

Pb Lb

• Source voltage

30 keV

• 20 min exposure

• Shield removes

Fe and Pb peaks

• Argon in air



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XRF measurement setup • MOXTEK MAGPRO, 60kV, 12W, Ag-anode

• 0.5 mm focal point

• Aluminum profile shielding removes Fe- &

Pb-signal

• JJ-XRAY ESRF-type slits

• Thorlabs translation stages

• Amptek X-123 SDD Spectrometer



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XRF image from Ca-line



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XRF image and reference burnout image

• Photo of

burnout

sample

• XRF image

Ca-line

0,5 mm

• Interpolated



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Exposure time and spot size limitation

• Practical slit and spectrometer mounting considerations

• The distance from the source to the slit limits the intensity

• 0.5 mm and 20 min exposure

• The distance from the slit to the

sample limits the spot size

• Alternative geometry 1 min exposure but ~2 mm spot size

• MoRe Research mounts a pinhole

close to the sensor

• 0.1 mm and “reasonable” exposure

Focal point Spot size Slit

Source

Slit



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Resolution comparison

• XRF images

• Sample 1: 0.1 mm resolution

• Calcium intensity (colormap jet)

• Sample 2: 0.5 mm resolution

• Sample 2 is previously compared to Burnout image

• Structure visibility limit <0.5 mm

• ”my opinion”

MoRe Sample

MIUN Sample



Copper fluorescence

Transmission measurement

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Calcium surface measurement

Paper s

am

ple

source

Slit

Spectrometer

Copper p

late



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Spectrum with copper plate behind paper sample



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Transmission image from Cu-line



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Comparison: XRF and Cu transmission image

The coating smooths the total thickness



Online applications

Visions

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Setup proposal for online measurement

Object

Incident beam

Detector

Scan

Collimator

• Columns transverse to the paper line

• Slit collimated line beam

• Stepper methodology

• Scanning summation along rows

• The movement gives image information

• 2D collimator needed

• to retrieve “enough” resolution XRF image

• Paperboard movement

~ 10 m/s

• Realistic source can be

• Liquid jet 500 W source



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Timepix 3 energy resolution

0

50

100

150

200

250

300

350

400

0 20 40 60 80 100 120 140

Ti Cu

• Energy resolution for Timepix3 with

a silicon sensor.

• No calibration applied. The spectrum

shows the resolution of Ti (4,5 keV)

and Cu (8,0 keV).

• The needed separation of Ca & Cu

is bigger than this separation.

• Provided by David Krapohl



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Thank you for listening

Welcome to Sundsvall and IWORID 18 next year!

Precision Scan-Imaging

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