Patent ID: 7417940

Claim:
An optical pick up, comprising: a laser diode which outputs a light in response to an input current; a photo diode which receives the light and outputs a voltage; a digital potentiometer which adjusts the voltage output by the photo diode according to a voltage adjusting signal, the digital potentiometer being included in the photo diode; and a controller which outputs the input current, sets a first reference voltage to be outputted by the photo diode according to the light, and outputs the voltage adjusting signal to the digital potentiometer according to a difference between the output voltage and the first reference voltage, wherein when the output voltage is equal to the first reference voltage, the input current is a first input current, and the controller outputs a second input current to the laser diode and sets a second reference voltage corresponding to the second input current to ascertain whether another output voltage of the photo diode is equal to the second reference voltage to confirm a sensitivity adjustment of the photo diode.