Fiber optics sensor

Fiber optics is a glass fiber which is used to carry signals in the form of pulses of light over distances up to 50 km without the need for repeaters. The term optical fibres indicate special forms of optical waveguides, the most important special features of which are:

  • rotationally symmetrical cross-section
  • Flexible
  • can be produced in great lengths

Fibre optic sensor:

Fiber optic sensors use emitters, receivers, flexion cables packed with thin fibers that transmit light. Light guides (optical fiber) can be screwed on the sensor or form a single unit with the sensor. This sensor can be used as a diffuse sensor. Light guide length is adjusted for each application.

Optical waveguides are glass or plastic translucent fibers that transmit light. Light follows the shape of the light guide, even if it’s curved. This is done through total internal reflection. “Solid” optical media is fiber (core n), with “thin” protection.

Depending on the sensor, there is a cable that can be separated from the emitter and receiver, or using a single cable. If a single cable is used, the emitter and receiver use various methods.

Glass fiber is used if the source of the emitter is infrared light. Fiber plastic is used if the source of the emitter is visible light. The optical fiber can be used with thru-beam sensors, scan retroreflectors, or diffuse scans.

In the thru-beam, the beam is emitted and received by the cable individually. In retroreflector and diffuse scans, the light is emitted and received with the same cable, divided into 2 (bifurcated) branches. The optical fiber is ideal for small objects or narrow censorship areas. The optical fiber has a shorter censorship area due to loss of light in fiber optic cables.

Fibre Optics bending:

For the bend radius must pay attention to the following practical rules:

  • The curved radius should not be less than 10 times the outer diameter of the sheath
  • Within a range of 15 mm from the sensor and the fiber optic head should not be bent
  • The main optical fiber plastic must not be bent or bent. Excessive tensile loads cause destruction. Excessive tensile loads cause damage. Contact with gasoline and organic solvents must be avoided

Fiber optic application:

  • Detection of very small objects
  • Used at temperatures up to 300 ° C
  • Use in a potentially explosive space
  • In areas with strong magnetic fields.


Instrumentation Engineer

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