The core of optical fiber, liquid core fiber, etc. are usually illuminated by microscopes of different wavelengths.

Optical fiber bundle used for lighting, referred to as optical fiber. Fiber Optic Fibers have a core made of a transparent material (typically glass fibers are made of silica).

Optical fiber transmission utilizes the principle of total reflection of light. In this fiber core medium, light is transmitted while maintaining the characteristics of its light waveform. The high refractive index core part is the main channel for light transmission, while the low refractive index shell covers the entire fiber casing, causing total reflection. , and therefore light can be transmitted in the fiber core.