1. A method of measuring a 3 dimensional (3D) image of a circuit board, the method comprising the steps of: establishing a correspondence between illumination adjustment command values and a brightness of a first illumination source by controlling a module control unit and an image acquisition unit through a central control unit for each of a plurality of illumination adjustment command values; establishing a phase-to-height conversion factor by controlling the module control unit and the image acquisition unit to obtain image data from a plurality of images captured by a camera coupled to the image acquisition unit; determining whether a measurement is to be performed in a normal inspection mode or a teaching mode; in the normal inspection mode, measuring a 3D shape of target objects on the circuit board by controlling the module control unit and the image acquisition unit through the central control unit; in the teaching mode, establishing height data for a bare circuit board by controlling the module control unit and the image acquisition unit through the central control unit; following establishment of the height data for a bare circuit board, measuring the 3D shape of target objects on the circuit board by controlling the module control unit and the image acquisition unit through the central control unit; and analyzing the measured 3D shape of target objects on the circuit board in the central control unit whether the 3D shape of the target objects is one of normal or abnormal.