Security method for monitoring an optical module and three-dimensional sensor using the same

A security method for monitoring an optical module, applied to a three-dimensional sensor including the optical module and a light source module opposite to each other, comprising:

• arranging at least one first inductive coil on the optical module and correspondingly arranging at least one second inductive coil on the light source module;
• inputting an alternative current to one of the at least one first inductive coil and the at least one second inductive coil and driving another of the at least one first inductive coil and the at least one second inductive coil to generate an inductive current;
• and
• continuing with detecting a value of the inductive current and determining whether an abnormality of the optical module occurs according to a variation of the value of the inductive current.