ST Drops Two Time-of-Flight Sensors for 3D Depth Sensing

February 28, 2024 by Jake Hertz

ST has newly released an all-in-one LiDAR module for 3D direct ToF and pushed another indirect ToF sensor into mass production.

STMicroelectronics has announced two time-of-flight (ToF) sensors for applications, including 3D LiDAR and deep vision. The VL53L9CA is a new direct time-of-flight (dToF) 3D LiDAR sensor offering nearly 2,300 measurement zones. The company also announced that China's Lanxin Technology has integrated ST's previously-released VD55H1 500k-pixel ToF sensor into Lanxin's mobile robot deep vision systems.



The all-in-one VL53L9CA can stream a post-processed 2D image, depth data, and a confidence map at 60 fps—the fastest on the market, according to ST.  

Devices like both the VL53L9CA and VD55H1 are critical for vision technology present in applications ranging from AR/VR to robotics.


All-in-One LiDAR Module for 3D Direct Time-of-Flight 

ST describes the VL53L9CA sensor as a 3D direct time-of-flight (dToF) all-in-one LiDAR module. The system is powered by a 940-nm invisible light vertical-cavity surface-emitting laser (VCSEL) covered by metasurface optical elements (MOE) and includes onboard computing resources and power management circuitry. 

What sets the VL53L9CA apart is its multizone ranging capability, allowing it to output distance measurements across up to 54 x 42 separate zones. This feature is critical for applications requiring a detailed spatial understanding of the environment, such as in advanced user interfaces, obstacle detection, and augmented reality technologies. The integration of on-chip postprocessing for streaming 2D IR images and depth maps, including indications of confidence level, further enhances its utility, providing valuable data for complex image processing and spatial analysis tasks.

Application schematic for the VL53L9

ST reports that the sensor can measure at distances ranging from less than 5 cm to over 10 m and at a frame rate of up to 60 Hz. Sophisticated histogram processing and algorithmic compensation techniques support this performance, effectively mitigating the impact of cover glass crosstalk and veiling glare—both common challenges in optical sensing technologies.

Designed with versatility in mind, the VL53L9CA comes in a compact form factor and is compatible with a broad spectrum of cover glass materials, making it useful for integration into a wide range of consumer electronics and industrial applications. 


3D Imaging for Indirect Time-of-Flight

In addition to the VL53L9CA, ST also announced that its VD55H1, a solution for 3D imaging technology tailored for indirect time-of-flight (iToF) applications, will be used in Lanxin Technology's mobile robot deep vision systems.

Equipped with a resolution of 0.54 MPix within a 672 x 804-pixel array, the VD55H1 comes in a compact 4.5 mm x 4.9 mm die. This compact size, combined with the device's use of backside-illuminated fast photodiode pixel technology, ensures high-precision depth mapping capabilities. According to ST, the sensor can achieve more than 85% demodulation contrast at 200 MHz, communicate via SPI, I2C, or LVDS, and achieve a standard power consumption of 80 mW.

Block diagram of the V55H1

Block diagram of the V55H1

One of the key features of the VD55H1 is its support for multifrequency operations up to three frequencies. This enhances depth resolution and mitigates interference from ambient lighting, a crucial factor in outdoor applications or environments with variable lighting conditions. The sensor's ability to operate at multiple frequencies also allows it to easily distinguish between objects at different depths, enhancing the sensor's utility in complex scenarios.

The VD55H1's versatility and high performance may make it a valuable component in products that rely on accurate and reliable depth sensing. According to ST, its applications extend beyond AR and gesture recognition to include robotics, where precise spatial awareness is critical, and security systems, where the ability to detect and analyze movements in three dimensions can enhance surveillance.


Plug and Sense

With more applications relying on image sensing, ST aims to put new ToF sensors in the hands of designers. Both fully integrated modules work easily alongside any microcontroller, requiring minimal overhead to get sensing immediately. The real value of these modules is their integration and ease of use. Users can set up the I2C channel and start sensing. 



All images used courtesy of STMicroelectronics.