TOF depth sensor based on laser speckle projection and distance measuring method thereof

A distance measuring method adopting a ToF depth sensor based on laser speckle projection, comprising a laser speckle projection unit and an image sensor, wherein the laser speckle projection unit is composed of a laser projector and a diffraction optical element (DOE);

• the laser projector is used for projecting periodic infrared laser signals with phase information to a detected space;
• the DOE is used for uniformly distributing a beam of incident infrared laser signals into L beams of emergent infrared laser signals, enabling each beam of emergent infrared laser signals to carry respective phase information, and beam diameters, divergence angles and wavefronts of the emergent infrared laser signals to be identical with those of the incident infrared laser signals, while only changing a transmission direction and controlling coded patterns projected out by laser speckles, wherein L is a positive integer greater than 1;
• and the image sensor is used for obtaining depth information, comprising the following steps:
• S100:
• projecting, by a laser projector, periodic infrared laser signals with phase information to a detected space;
• S200:
• uniformly distributing, by a DOE, incident infrared laser signals into L beams of emergent infrared laser signals, each beam of the emergent infrared laser signals forming a laser speckle after reaching the detected space and controlling a coded pattern projected out by the laser speckle;
• S300:
• first, obtaining an individual pixel size of the image sensor;
• next, forming, by each pixel of the image sensor and each beam of emergent infrared laser signals, laser speckles after reaching the detected space for transmitting and receiving view field matching;
• and then, calculating a phase difference between the incident infrared laser signals and the emergent infrared laser signals to obtain depth information.