Development of an Optical Bubble Counting Algorithm (OBCA)

1. Development of anOptical Bubble Counting Algorithm (OBCA) Arkadiusz Kalicki PERG Group, Institute of Electronic Systems, Warsaw University of Technology in cooperation with Ph.D Bhaskar Mukherjee, DESY Hamburg Dominik Rybka, PERG

2. Plan of presentation • Introduction • Bubble dosimeter • OBCA, counting algorithm • Results • Conclusions • Future plans

3. Introduction • There are different types of dosimeters • For our experiment we need real-time neutron dose monitoring • The dose should be easy to read, especially automatically • We need dosimeters very frequent, so they should be low cost and reusable • Neutron bubble detector is a good choice • For automatic reading of bubble dosimeter we developed Optical Bubble Counting Algorithm (OBCA)

4. Neutron Bubble Detector • How bubble dosimeter works • The detector consists of an elastic polymer with droplets of superheated liquid • When these droplets are stuck by neutron they form small gas bubbles • The bubbles remain fixed in the polymer to provide a real time record of the dose. • Bubble dosimeter features • Is reusable • The number of bubbles formed is directly proportional to the dose • Response is independent of dose rate • Detectors are very compact and light-weight. Bubble dosimeters we used are producedbyBTIBUBBLE Technology Industries.

5. Counting algorithm • Read image • Detect edges with Canny edge detection algorithm: • smooth the image with Gaussian filter to eliminate any noise • find the image gradient to highlight regions with high spatial derivatives • track along these regions and suppresses any pixel that is not at the maximum • reduce gradient array by hysteresis • track along the remaining pixels that have not been suppressed • hysteresis uses two thresholds and if the magnitude: • is below the first threshold, • then it is set to zero (non-edge) • is above the high threshold, • then it is made an edge • is between the 2 thresholds, • then it is set to zero unless there is a path from this pixel to a pixel with a gradient above T2 • Eliminate straight lines and small objects • Count bubbles.

6. OBCA version 1 • Application written in Java Swing • Reads any type of image (jpg, bmp, etc.) • Runs on any OS with JRE • User friendly interface • Read image • Find angles • Count bubbles

7. OBCA version 1 OBCA, read image

8. OBCA version 1 OBCA, find angles

9. OBCA version 1 OBCA, count bubbles: 44, manually 40

10. Results Number of bubbles manually counted by three different persons and counted by OBCA v 1

11. Conclusion • Algorithm works fine • as shown in the table error in number of counted bubbles is small, even for manual counting is a flew percents • sometimes there is a problem with elimination of non bubble objects • it is not accurate when there are overlapped bubbles – we need algorithm based on shape recognition • Algorithm can be used for real-time bubble monitoring • OBCA has user friendly graphical interface, can by run on any operating system with JRE

12. OBCA the future version Original image High-pass filter Histogram manipulation delete small objects 3D view of bubbles

13. Thank you