Light Sensors

1) PhotoResistor Light Detector:

This detector is automatically supplied with each Light Controller and comes in a 3-pc. light-sensing kit – the CL9 kit.

(2 for either IR, or for UV installations in curing applications)

  • Comprised of a photoResistor with mount
  • Extras can be ordered as well

Socket Mount PhotoResistor Detector Retaining Ring

2) PhotoDiode Light Detector:

MERCRON’s own, temperature-stabilized photoDiode detector: the “PD”

  • Optional, but highly recommended
  • Has deliberately-designed features with distinct advantages in Machine Vision applications (See below)
  • Completely interchangeable with the photoResistor normally supplied
  • Can be ordered separately


  • Can be retrofitted with an external 5-Volt source
  • Has no “light memory”, no hysteresis
  • Has basically same spectral band-pass that a CCD camera has
  • Sensitive to all colors – even UV
  • Will compensate correctly for color changes due to lamp aging
  • Permits true “Instant On” Regulation for Machine Vision Lighting Systems
  • Available in 5 levels of sensitivity – 10 to 200 – in the order of “doubling sensitivity” (See Models below)
PDR 47 Fluorescents
PDS 10, 20, 47, 100, 200 Metal Halide, Sodium
PDT 10, 20, 47, 100, 200 Tungsten
PDV 100, 200 Ultraviolet Recommended for Curing Applications

Some of our customers over the past 30 years: