LineLIDAR sensor LL-60A

The transmitter of LineLIDAR sensor LL-60A creates an optical pulse applied for distance measurement with a laser, which is spread like a line. The receiver is a SPAD receiver matrix, which comprises 256 rows. Even single photons can be detected with SPAD detectors. 

Accurate time-to-digital converters (TDCs) are also integrated into the receiver, which work alongside SPAD detectors. These watches start measuring time when the laser pulse leaves the device and, in an ideal situation, stop measuring due to the breakthrough caused by the laser pulse reflected from the object into the SPAD detector. Based on the elapsed time, it is possible to calculate how far a photon from a certain direction has traveled. As a technology this is called Direct Time-of-Flight (ToF). 

With the help of optics, the desired field of view (FOV) and angular resolution are achieved, from which direction the individual SPAD detector detects photons. With the help of transmitter optics, the laser pulse is spread at a planned angle in the case of a 2D lineradar.

Above is presented an observation picture of how the laser pulse is spread into a line, from which the receiver detects the bounced photons. 

For this device, the FOV value of the receiving optics has been chosen to be 60°, which means about 0.23° angular resolution of a single SPAD row when the receiver has 256 adjacent SPAD detectors.

Below is presented a measurement case where the line is rotated to create a 3D point cloud of surrounding environment.