Transformer oil quality assessment based on lens-free holographic microscopy

In order to avoid serious problems caused by excessive gas in transformer oil and to realize online monitoring of transformer oil, we propose a method based on lens-free holographic microscopy for transformer oil quality assessment. Using a lens-free device, we can obtain a hologram of the gas bubbles with a large field of view in transformer oil. After the reconstruction, the quantitative phase and shape information of the gas bubbles in the oil can be acquired, thus we can further calculate the parameter of the area, volume, amount, and gas to oil volume ratio of the gas bubbles in transformer oil, which can be used to evaluate the quality of transformer oil effectively. During the experiment, we measured the smallest diameter of the gas bubble in oil was 8 & mu;m. The newly designed method provides a new solution for the assessment of transformer oil quality.