Stanford EE259 I Camera principle of operation and architectures, image formation I 2023 I Lec. 19

TL;DR

This comprehensive analysis explores the digital signal processing (DSP) techniques used in lidar and imaging systems, including direct detection lidar, coherent detection lidar, and cameras.

Transcript

okay uh let's get started uh as usual with a quick review of a previous lecture so last time we started looking at the system architectures for the two main types of lidar which is the direct detection lidar and querying detection lighter or coherent lidar in short and the main the main difference is is basically the signal that that that you recei... Read More

Key Insights

• 🧡 DSP in lidar systems varies depending on the type of lidar, with direct detection lidar focusing on range estimation and coherent detection lidar also including velocity estimation.
• 💁 Coherent detection lidar is more complex but provides more information due to its ability to capture amplitude and phase information of the waveform.
• 😁 DOA estimation in lidar is achieved through the geometry of the photodetector array or beam scanner, and does not require additional DSP algorithms.
• ✋ Lidar is a highly capable imaging technology, but it has limitations including high cost, sensitivity to poor weather conditions, and potential interference.
• 👶 Ongoing research is focused on improving lidar performance in bad weather and developing new waveforms and models to enhance its capabilities.

Questions & Answers

Q: What is the main difference between direct detection and coherent detection lidar?

The main difference is that direct detection lidar can only measure range, while coherent detection lidar can measure both range and velocity.

Q: How does direct detection lidar estimate range?

Direct detection lidar estimates range by analyzing the intensity of the reflected light using a simple photodetector.

Q: What additional information can be obtained from coherent detection lidar?

Coherent detection lidar can provide both range and velocity information by analyzing the amplitude and phase of the received waveform.

Q: How is direction of arrival (DOA) estimated in lidar systems?

In flashlight lidar, DOA is determined by the geometry of the photodetector array. In scanning lidar, DOA is known based on the position of the beam scanner, which can be either read directly or modeled.

Summary & Key Takeaways

• Lidar systems can be categorized into direct detection and coherent detection, with direct detection lidar only capable of measuring range, while coherent detection lidar can also measure velocity.

• Direct detection lidar uses a simple photodetector to measure the intensity of the reflected light, while coherent detection lidar employs a more complex optical receiver to capture both amplitude and phase information of the waveform.

• DSP in lidar systems involves estimating range and velocity using waveform analysis and Fourier transforms, while DOA estimation is achieved through the geometry of the photodetector array or beam scanner.