Light and Optical Sensing

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Photodiodes

Photodiodes are semiconductor devices that convert light into electrical current. They are fundamental components in many optical sensing applications.

Operating Principles
  • Photovoltaic effect
  • PN junction operation
  • Spectral response
  • Response time
  • Dark current
Basic Circuit
// Photodiode light measurement
const int photoPin = A0;
int lightLevel;

void setup() {
  pinMode(photoPin, INPUT);
}

int measureLight() {
  lightLevel = analogRead(photoPin);
  // Convert to lux
  float voltage = lightLevel * (5.0 / 1023.0);
  float lux = voltage * 100.0;
  return lux;
}