We all know that laser diodes have many uses. In traditional industries, laser diodes are usually used to make laser modules. So do you know what band modules are usually selected for industrial sensors? Let's take a look at it together.

First, the common band distribution

There are three kinds of laser bands that are most common in industrial sensors:

Red light (630~690nm), near infrared (780~980nm), and even mid-infrared (1310nm, 1550nm).

Why these guys? There are three main reasons: first, laser diodes are mature and cheap in the market; Second, optical devices (lenses, filters, photodetectors) have high matching; Third, the safety level of human eyes is controllable.

Second, the use of different bands

1. Red band (630~690nm)

This band is the most intuitive, and the human eye can directly see the red spot, so it is often used in sensors, rangefinders, laser aiming, light curtains, security detection and so on.

The light in this band has the advantages of intuitive positioning and quick response, but the penetration is slightly poor, and it is easy to be scattered when encountering dust and smoke.

2. Near infrared band (780~980nm)

This is the most commonly used industrial sensing band.

It is invisible, but it has stronger penetrating power, and is especially suitable for high-precision sensing such as displacement measurement, thickness detection, speed monitoring and surface contour scanning.

For example, in precision machinery manufacturing or automatic detection line, laser triangulation and laser displacement sensors are mostly laser modules in 780nm or 850nm band.

One more thing, this band of light is very sensitive to CCD/CMOS sensors, so it is often used with image recognition systems.

3. Mid-infrared band (1310nm, 1550nm)

This band is generally used in long-distance ranging or high-security level detection in industry.

Because lasers of 1310nm and 1550nm are less harmful to human retina, they are widely used in communication, mapping and unmanned lidar.

Like some building ranging equipment, terrain scanning and 3D imaging sensors, 1550nm laser is commonly used. However, this kind of module has higher cost and stricter requirements for optical system.