Confocal microscopy based on dual blur depth measurement

In this paper, we propose a confocal microscopy based on dual blur depth measurement (DBCM). The first blur is defocus blur, and the second blur is artificial convolutional blur. First, the DBCM blurs the defocus image using a known Gaussian kernel and calculates the edge gradient ratio between it and the re-blurred image. Then, the axial measurement of edge positions is based on a calibration measurement curve. Finally, depth information is inferred from the edges using the original image. Experiments show that the DBCM can achieve depth measurement in a single image. In a 10×/0.25 objective, the error measured for a step sample of 4.7397 µm is 0.23 µm. The relative error rate is 4.8%.