This is another epic video by the famous The Action Lab YouTube channel. This time showing the mechanics of facial recognition via a grid of lasers that project from many modern phones. The light projected for facial recognition is in the infrared (IR) range and can be made visible with an IR camera. The pattern that becomes visible of many dots which when deformed in the reflection back to the camera can determine the contours of your face. Beyond just facial recognition, the IR lasers can be used to scan around objects to produce a full 3D rendering of the object.
On the back of some phones, such as the new iPhone 12, there equips a LIDAR (Light Detection and Ranging) scanner which can measure the distance of objects via the time it takes for the lasers to reflect back from the object. This allows for forming a full 3D rendering of the environment around you. LIDAR uses UV, visible, and near IR (on the faster frequency IR range) light. An IR camera can be used to see some of the projected LIDAR laser patterns, which shows it to be more spread out than the typical IR lasers for facial recognition. Since it uses some non-visible light, the LIDAR scanner can be used even in the dark, which renders a black and white 3D grid pattern of the surrounding environment.
The mechanism behind projecting thousands of lasers from such a small region involves bouncing light back and forth across tiny mirrors that gradually becomes more transparent until the light finally escapes in a more uniform form as a LASER (Light Amplification by Stimulated Emission of Radiation). Amazing stuff!