In industrial inspection, some scenarios place special demands on fiber — high temperatures, harsh conditions. Standard plastic optical fiber can't handle it. Take flame detection. Burners, boilers, and industrial furnaces operate at extreme temperatures. Sensors can't be placed on-site, but the flame's optical signal needs to be transmitted out. That's where glass fiber bundles come in. Why Glass? Glass fiber bundles offer far higher temperature resistance than plastic. Plastic optical fiber typically maxes out at 85°C, while glass fiber operates reliably at up to 350°C — suitable for high-temperature industrial environments. Another key advantage: high numerical aperture. Glass fiber bundles have a wide acceptance angle, capturing more light from divergent sources like LEDs or halogen lamps. For flame detection — where weak optical signals need to be captured — high NA means higher coupling efficiency.