System and method for foreign object detection in wireless power transfer

A pattern light laser-based foreign object detection (FOD) device in a wireless power transfer system including a power transmitter and a power receiver, the device comprising:

• a laser module comprising:
• a laser light source configured to emit a dot-shaped light,
• a first diffraction grating filter configured to convert the dot-shaped light into a first multi-line pattern,
• a second diffraction grating filter spaced apart from and aligned with the first diffraction grating filter, the second diffraction grating filter configured to convert the first multi-line pattern into a second multi-line pattern having more lines of light than the first multi-line pattern, and
• a window configured to transmit the second multi-line pattern to an object, wherein the second diffraction grating filter is disposed between the first diffraction grating filter and the window;
• and
• a detector spaced apart from the laser module and configured to receive a pattern light reflected from the object and detect a pattern image from the reflected pattern light.