How does a laser sensor work?

The principle of operation of a laser radar includes the following main stages:

Emission of laser pulses:

A laser radar emits a series of laser pulses in the direction of the target area using a laser emitter.
These laser pulses propagate through the air and serve as the basis for detecting the surrounding environment.
Propagation and reflection of pulses:

When a laser pulse encounters an object, it is reflected.
The reflected laser pulse carries information about the target object.
Receiving reflected pulses:

The laser radar receiver is responsible for receiving these reflected laser pulses.
During this process, information about the position, shape, and other characteristics of the target object is collected.
Calculating distance and angle:

Using the flight time of the laser pulse and the relative position of the emitter and receiver, it is possible to calculate the distance between the target and the laser radar.
At the same time, by processing information about the direction of the reflected pulse, it is possible to determine the angular relationship between the target and the laser radar.
Building an image of the environment:

By measuring and processing data from multiple laser pulses, a laser sensor can accumulate a large amount of information about the environment.
This information is used to build a three-dimensional cloud map of the environment or other forms of information representation, which allows for the perception and analysis of the environment.

-General classification of laser sensors

General classification of laser sensors

The classification of laser sensors is based on the number of lines and the scanning method. Below is a detailed classification and characteristics of each type:

I. By number of lines

Single-line laser sensor

Characteristics: can only perform flat scanning, has high scanning speed, resolution, and reliability.

Application: mainly used in service robots and other systems where high height accuracy is not required, but obstacle avoidance is necessary.

Multi-line laser sensor

Features: can recognize the height of objects, expensive.

Application: mainly used in areas such as driverless cars.

Number of lines: 4-128 lines are mainly used in the industry.

II. By scanning method

Mechanical rotating laser sensor

Features: the emission system and the reception system have physical rotation, 3D scanning is performed by a rotating emitter.

Internal structure: complex, includes a laser, scanner, photoelectric detector, as well as positioning and navigation devices.

Disadvantages: high equipment cost, difficulty in ensuring stable operation over a long period of time, service life in the industry is mainly 20–30 thousand hours (about 2–3 years with normal use).

Laser sensor with micro mirror (hybrid solid-state)

Features: the receiving and transmitting modules remain stationary, laser scanning is performed by the movement of a mirror driven by an electric motor.

Advantages: simple mechanical design, relatively small size, easy to mass produce.

Application: widely used in autonomous driving.

MEMS laser radar (hybrid solid-state)

Features: uses micro-mirror scanning, implements laser radar beam control on the emission side at the micro level.

Advantages: mature technology, high degree of integration, possibility of reducing size and cost.

Disadvantages: limited scanning range and viewing angle, low stability, difficulty in passing vehicles, low consistency in mass production.

Image: none (but the principle of operation can be understood from the text description)

Flat matrix laser sensor (Flash, solid-state)

Features: emits a large section of the laser beam covering the detection area for a short time and maps the surrounding environment using a highly sensitive receiver.

Advantages: Ability to quickly record the entire scene, avoiding the influence of radar or target movement during scanning.

Disadvantages: Difficulty in detecting at long distances.

Optical phased array laser sensor (OPA, solid-state)

Features: uses an array of multiple light sources, controlling the time difference in the emission of each source, synthesizes a main beam with a specific direction, allowing scanning in different directions.

Complexity: processing complexity, requires that the element size does not exceed half the wavelength.

Thus, the classification of laser radars is mainly based on the number of lines and the scanning method. Different types of laser radars vary in characteristics, applications, advantages, and disadvantages, and users can choose the appropriate type of laser radar depending on their specific needs.