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Sensors and Actuators for Robotics

23RIPC210

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Photoelectric sensors �1.The photoelectric sensor �

  • Photocathode is made of low work-function material → enables easy emission of electrons.
  • Incident light causes electron emission, which are accelerated toward the photoanode due to applied potential difference.
  • The resulting current is proportional to light intensity.
  • Quantum Efficiency:
    • Number of electrons emitted per photon
    • Depends on photocathode material
  • Materials Used:
    • Metals (low efficiency)
    • Cesium-based materials (high efficiency, wide spectral response: UV to IR ~1000 nm)
  • Construction:
    • Enclosed in vacuum or low-pressure noble gas (argon)
    • Gas enhances gain via ionization collisions
  • Advanced Technology (NEA surfaces):
    • Uses cesium-coated semiconductor
    • Operates at lower voltage compared to classical sensors
  • Note: Traditional sensors require high operating voltage (hundreds of volts).

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