J. Eur. Opt. Society-Rapid Publ. 22, 26( 2026) 271
Fig. 2. LC-OCT setup. The tapered microfiber under study is not shown to scale and is enlarged for illustration purposes.
is generated by averaging 100 frames to reduce photon shot noise. The device is mechanically stable, ensuring that this averaging does not introduce blur that could degrade spatial resolution.
3 Results and discussion
Figures 3a – 3e show cross-sectional images of the tapered section of fiber 1 for different cladding diameters. The white traces indicate the cladding, and the small points at the center of the images in Figures 3a – 3c indicate the core. Because the cladding and core surfaces are smooth, the optical reflection is predominantly specular. Only light reflected from surface regions that are nearly perpendicular to the illumination direction is detected. Fitting the visible cladding boundary in the image with a circle confirms its circular geometry, although only a portion of it is observed. From the initial diameter of 125 lm down to a cladding diameter of approximately 67 lm, the cladding / core interface could still be observed despite the small step index. The resolution of the LC-OCT device enabled to measure the diameter of the thinnest part, namely the microfiber( Figs. 3e and 3f), yielding a diameter value of 1.6 ± 0.1 lm. This measurement is in very good agreement with the value obtained by conventional optical microscopy using an immersion microscope objective( see Fig. 3g), giving a diameter of 1.5 ± 0.1 lm. Both measurements are also in good agreement with the targeted diameter of 1.71 lm. Performing measurements by Scanning Electron