Special thanks to Professor L. Jay Guo for advising our team and Dr. Qiaochu Li for supporting and approving our work. Project funded by Zhejiang University In affiliation with Optics & Photonics Laboratory - EECS @ Michigan

View our report

What is Laser shadowgraphy?

Laser shadowgraphy is an imaging technique designed to capture non-uniformities in transparent media like air or water. Here, this technique is used to study the mechnism of Photo-acoustic effect, which is the formation of acoustic waves upon the absorption of modulated or pulsed light mainly through thermoplastic expansion.

Our goal - Count the dark bubbles

The team at our lab has developed some sort of PA lens that can generate and focus densely powered ultrasonic waves strong enough to tear apart water molecules. To have a better insight into this phenomenon, we need to acquire data regarding the quantity and size of the bubble emerged during varied cavitation voltage.

Gist of Ideas

• Image preprocessing - Denoising, Equalizing,
• Segmenting - Using modified KNN background segmentation algorithm
• Morphological Operations - Polishing the mask frame
• Overlapping detection - Using algorithm explained in the report
• Count and plot the result

Download our report

Result

Demonstration of capturing bubbles Count and plot bubble size distribution

Running our code

Dependencies

• python 3.6
• pip install
  • opencv-python
  • Pillow
  • pypiwin32
  • matplotlib
  • tkinter

cd into current directory and type in python xx.py or just run hello.bat main.py is the main tkinter application file. All the algorithms and tools used are placed in \MyDIPUtils\

Interface

Look up help for instructions Hit the button and pick up a video file to run. Then select the region where there could be bubbles. When finished, result will be shown as a histograph.

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