An aerospace technician uses a flexible optical borescope (an industrial endoscope) to inspect the interior of a gas turbine blade for micro-cracks and thermal degradation.
Identify the two types of optical fibre bundles used in this borescope. Compare their roles, and explain why a cladding layer is critical for one bundle but can be omitted for the other.
High-speed telecommunication networks rely on narrow-core single-mode fibres and monochromatic light sources to mitigate modal and material dispersion.
Explain why these design features are redundant for a typical 1.5 m1.5\text{ m}1.5 m borescope. Describe the negative consequences that would occur if a design engineer attempted to incorporate single-mode fibres and monochromatic illumination into this inspection system.
