Rings

Broad rings

Detection and quantification of grey level differences of ca. 1% in the electrode particles – local tomography and broad ring artifacts are making this challenging task even more difficult. Standard solutions used at the TOMCAT beamline (e.g. constant padding) are not sufficient in the phase retrieved case [B36], if small grey level differences need to be reliably detected. A more sophisticated flat-field correction might help for the ring artefact problem.

tomo_ID

00071

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00071

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tomo_00071

Instrument

SLS TOMCAT

Sample name

SLS_01

X-ray energy

24.999 keV

Sample-to-detector distance

15 mm

Scan Range

180 degree

Number of Projections

1201

White Fields

200 (100 before 100 after)

Dark Fields

10

Pixel size

0.65 µm

Rotation axis location

1302.50

To load the data sets and perform a basic reconstruction using tomopy

tomopy recon --file-name tomo_00071.h5 --rotation-axis 1302.50

To enable phase retrieval un-comment the appropriate setting in tomopy_rec.py

Soft Tissue

To limit radiation damage of soft tissue, the energy is set in the hard x-ray regime. Samples are weakly absorbing and generate severe ring artefact. Below are two soft tissue sample measurements collected as follows:

tomo_ID

00072

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00072

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tomo_00072

Instrument

APS 2-BM

Sample name

soft tissue

X-ray energy

20 keV

Sample-to-detector distance

15 mm

Scan Range

180 degree

Number of Projections

1500

White Fields

10

Dark Fields

10

Pixel size

1.43 µm

Rotation axis location

1403

tomo_ID

00076

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00076

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tomo_00076

Instrument

APS 2-BM

Detector

PCO edge

Sample name

soft tissue

X-ray energy

braod 60-70 keV

Exposure Time

100 ms

Scan Type

Fly Scan

Scan Speed

0.75 deg/s

Shutter Mode

Rolling

Scintillator

10um LuAG

Sample-to-detector distance

90 mm

Scan Range

180 degree

Number of Projections

2000

White Fields

10 pre scan

Dark Fields

10

Pixel size

2.2 µm

Rotation axis location

1275

To load the data sets and perform a basic reconstruction using tomopy

tomopy recon --file-name tomo_00072.h5 --rotation-axis 1403
tomopy recon --file-name tomo_00076.h5 --rotation-axis 1275

To enable phase retrieval un-comment the appropriate setting in tomopy_rec.py

Al Samples

Here we present two measuremend done on the same Al sample presenting mild ring artefacts. Mesurements have a different white field data collection strategy.

tomo_ID

00073

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00073

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tomo_00073

Instrument

APS 2-BM

Sample name

AlO2_01

X-ray energy

25 keV

Sample-to-detector distance

10 mm

Scan Range

180 degree

Number of Projections

1500

White Fields

100 at the end

Dark Fields

1

Pixel size

0.74 µm

Rotation axis location

1001.2

tomo_ID

00074

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00074

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tomo_00074

Instrument

APS 2-BM

Sample name

AlO2_02

X-ray energy

25 keV

Sample-to-detector distance

10 mm

Scan Range

180 degree

Number of Projections

1500

White Fields

200 (100 pre 100 post)

Dark Fields

1

Pixel size

0.74 µm

Rotation axis location

1001.6

White beam

To increase data collection speed on a BM source, the beamline is set in white beam mode. This data set contains mild ring artefacts and was collected with the following experimental conditions:

tomo_ID

00075

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00075

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tomo_00075

Instrument

APS 2-BM

Detector

PCO DIMAX

Exposure Time

5 ms

Scan Type

Fly Scan

Scan Speed

9 deg/s

Shutter Mode

Rolling

Scintillator

100um LuAG 28mm Glass

Sample name

Ceramic Rod + Clay + Wire

X-ray energy

white beam

Sample-to-detector distance

110 mm

Scan Range

180 degree

Number of Projections

3000

White Fields

200 (100 pre 100 post)

Dark Fields

none

Pixel size

1.43 µm

Rotation axis location

1010

To load the data sets and perform a basic reconstruction using tomopy

tomopy recon --file-name tomo_00073.h5 --rotation-axis 1001.2
tomopy recon --file-name tomo_00074.h5 --rotation-axis 1001.6
tomopy recon --file-name tomo_00075.h5 --rotation-axis 1010

To enable phase retrieval un-comment the appropriate setting in tomopy_rec.py

add datasets APS05

from https://drive.google.com/drive/folders/0B78bW1AwveI_WVdXQlBRMVBKQk0