LiDAR

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What are the challenges with LiDAR?

Essentially, LiDAR is a ranging device, which measures the distance to a target. The distance is measured by sending a short laser pulse and recording the time lapse between outgoing light pulse and the detection of the reflected (back-scattered) light pulse. 

There are some well-known challenges with operational LiDAR systems. These challenges depend on the type of LiDAR system. Here are some examples:

  • The isolation and rejection of signal from the emitted beam - The radiance of the probing beam is generally much greater than that of the return beam. Care must be taken to make sure the probing beam is not reflected or scattered by the system back into the receiver such that the detector is saturated and unable to detect external targets.
  • Spurious returns from debris in the atmosphere between the transmitter and the intended targets - The debris can cause such a strong spurious return that the return from the intended targets is not reliably detected.
  • Limitations on available optical power -A system with more power in the beam provides higher accuracy but is more expensive to operate.
  • Scanning speed-Safety can be an issue when the laser source is operating at a frequency dangerous to human eyes.  This issue is being mitigated by other approaches such as flash LiDAR which illuminate a large area all at once and by operating at eye-safe wavelengths.
  • Device crosstalk-signals from nearby LiDAR devices might interfere with the signal of interest.  The challenge faced now is how to differentiate signals emitted by other LiDAR devices nearby.   Various approaches with signal chirping and isolation are under development.
  • Cost and maintenance of LiDAR systems – These systems are more expensive than some alternative types of sensors however there is active development to overcome the high cost and produce systems at lower prices for wider use.  Rejection of returns from unintended objects- This is similar to the rejection of atmospheric spurious signal as mentioned previously. However, it can also happen in clear air scenarios. Addressing this challenge generally involves minimizing the size of the beam at various target distances as well as over the field-of-view received back at the LiDAR receiver


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