Profile measurement system and profile measurement method

A profile measurement system comprising:

• a light projector configured to project a pattern of light on an object, the pattern comprising at least one geometrical shape, wherein the light projector comprises:
• a light source configured to provide light;
• a mask disposed on a transmission path of the light and having an aperture to allow a portion of the light to pass through and to generate the pattern;
• and
• an optical system disposed on the transmission path of the light and comprising a variable focal length lens element, wherein the optical system is configured to project the pattern at different projection distances;
• an imaging device configured to capture images of the pattern of light projected at the different projection distances, wherein the imaging device comprises a lens system and an imaging sensor;
• a control system configured to control a projection distance of the light projector and a focus distance of the imaging device;
• and
• a processing unit configured to obtain in-focus pixels in the captured images, generate mask images each containing a mask region and an in-focus region based on the in-focus pixels, reconstruct a large depth of field pattern image based on the captured images and reconstruct the object profile.