What are modulated and non-modulated of Photomicro sensors Used for Industrial Equipment?

The following table shows the sensing method and characteristics for modulated and non-modulated light.

  Non-modulated Modulated
Sensing method Method used to detect light steadily
emitted by the emitter element
Method used to detect light emitted in
pulses by the emitter element
Characteristic Cost Lower than modulated models Higher than non-modulated models
External light
interference
Susceptibility to ambient light Resistant to ambient light