Patent ID: 7868299

Claim:
A method for detecting radiant energy with a light sensing apparatus, the light sensing apparatus comprising a phototransistor, a sensitivity adjusting circuit and a signal conditioning circuit having a sensor output terminal, the method comprising: determining a first power level and a second power level lower than the first power level of a UV lamp system; detecting radiant energy from the UV lamp system at the first power level and at the second power level, respectively; and adjusting the light sensing apparatus so that the light sensing apparatus is able to provide a first signal that corresponds to the first power level and a second signal that corresponds to the second power level, wherein: the phototransistor has a first terminal coupled to the sensor output terminal, a second terminal coupled to ground and a third terminal coupled to the sensitivity adjusting circuit, the sensitivity adjusting circuit includes: a first capacitor coupled to the third terminal; and an adjustable resistance coupled to the third terminal in parallel with the capacitor and sensitivity of the phototransistor circuit is adjustable by the adjustable resistance.