Disclosed is a method for calibrating an optical component, such as a DWDM, a thin film filter, a collimator, and a wave-guide. The method includes the steps of projecting a laser beam through the optical component, detecting the transmitting power while moving the optical component until the transmitting power is maximum to determine a local area, and detecting the reflected power while moving the optical component with fine steps within the local area until the reflected power is minimum, where an optimum point is located, which gives the maximum transmitting power and minimum reflected power.