Comparison of transverse mode instability in Yb, Tm and Ho doped bent high-power fiber amplifiers

Abstract

Dust particle artifacts are present in all imaging modalities but have more adverse consequences in medical images like retinal images. They could be mistaken as small lesions, such as microaneurysms. We propose a method for detecting and accurately segmenting dust artifacts in retinal images based on multi-scale template-matching on several input images and an iterative segmentation via an inpainting approach. The inpainting is done through dictionary learning and sparse-based representation. The artifact segmentation is refined by comparing the original image to the initial restoration. On average, 90% of the dust artifacts were detected in the test images, with state-of-theart restoration results. All detected artifacts were accurately segmented and removed. Even the most challenging artifacts located on top of blood vessels were removed. Thus, ensuring the continuity of the retinal structures. The proposed method successfully detects and removes dust artifacts in retinal images, which could be used to avoid false-positive lesion detections or as an image quality criterion. An implementation of the proposed algorithm can be accessed and executed through a Code Ocean compute capsule.

Investigating changes in the electric field profiles of transverse modes in fibres due to bending

“…Reducing the radius of the fibre core and enhancing the value of the parameter of NA, the modes coupling decreases as a result of increasing the modes separation frequency. Also bending the fibre increases the separation frequency, however in fibres with high NA or low core diameter, the amount of increase in separation frequency due to bending effect is less [11].…”

“…Development of optical fibre applications, including lasers and fibre amplifiers [8][9][10], control of mode instability [11][12][13][14][15], fibre sensors [16,17], material detection using evanescent fields [18], and telecommunication applications for data and information transmission [19][20][21], necessitates a comprehensive investigation into the behaviour of electric fields of fibre modes. Additionally, certain types of fibres with doughnut type or annular intensity distribution (Mode LP 02 ) can find utility in areas, such as optical tweezers [22] and scanning and treatment of internal surfaces of pipes [23,24].…”