What is the working principle of ToF?

      ToF (Time of Flight) is actually a deep information measurement scheme, which is mainly composed of an infrared light projector and a receiving module. The projector projects infrared light outward. The infrared light is reflected by the measured object and received by the receiving module. By recording the time when the infrared light is emitted from the time of receiving, the depth information of the illuminated object is calculated, and 3D modeling is completed.  ToF has been widely used in many industrial fields such as surveying, logistics, and unmanned driving. The program is relatively mature. Now, its application in the field of consumer electronics has gradually increased. 

      The ToF method can generally be divided into two types depending on the modulation method: Pulsed Modulation and Continuous Wave Modulation. Pulse modulation requires high-precision clock measurement, and needs to emit high-frequency high-intensity laser. Currently, in practical applications, sine wave modulation is usually used, and the phase offset method is detected to realize the function of measuring distance. Figure 1 depicts the basic principles of a ToF camera (continuous wave). 

Figure 1: How the ToF depth camera works. 

      Although the accuracy of 3D structured light is higher in depth measurement, the process is relatively complicated and has relatively high limits on ambient light and recognition distance. ToF is more adaptable to ambient light, the recognition distance can reach 10m, the response time is faster, and the process difficulty is relatively low. Therefore, many manufacturers are now more willing to choose ToF 3D sensing solutions. 

      In general, the advantages of ToF are mainly: 

        1) The interference from ambient light is relatively small; 

        2) The detection distance is long. It can reach several tens of meters with enough laser energy. The ToF technology currently used in consumer electronics is up to 10 meters; 

        3) Small size. 

      Of course, ToF also has some obvious problems: 

        1) Resource consumption is large. This scheme requires multiple sampling integrations when detecting the phase offset, and the calculation amount is large. 

        2) The edge accuracy is low. 

        3) Limited to resource consumption and filtering, there is no way to achieve higher frame rate and resolution. , 

        4) High requirements on equipment, especially time measurement module. 

If you want to know more, our website has product specifications for ToF, you can go to ALLICDATA ELECTRONICS LIMITED to get more information