Light sources of 3D scanners

The basic principle of 3D scanning is the projection of a light pattern or laser crosses onto the surface of the scanned object and capture of this projection using a camera or multiple cameras. A large number of points are created on the computer using triangulation, from which the polygon network is reconstructed. That's the basic principle in a nutshell, and now we'll take a closer look at the individual light sources of 3D scanners.

Structured light

Structured light can be white or blue. The advantage of using structured light is the possibility of faster scanning, capturing the texture of the object. For stationary scanners, they provide higher details of the scanned object. The disadvantage is problematic scanning outdoors or in well-lit areas and poorer quality of scanning dark and shiny surfaces. The most common light patterns are phase shift, light streaks and point projections.

Phase shift

The principle consists in the projection of light, which has the course of a sine curve, see Figure 1. Each projection is always shifted by some part. Scrolling creates rows of gradient moving bars, see GIF. Due to the curvature of the surface, the transmitted phase will change compared to the expected phase, see Figure 3, from these differences a 3D model can be reconstructed. Phase shift is used by stationary scanners.

Light streaks

They give the ability to scan while moving and increase the frame rate. The shape does not change, the deformation of the stripes on the surface is sensed. Light strips are used, for example, by the Go!SCAN Spark scanner.

Point projection

The projected point pattern encodes the scene u by assigning a certain property to the points in the scene. Such a unique marking of the points will allow the evaluation of the change between the original pattern and the pattern curved according to the surface of the examined object.

Sources of structured light serve as:

• DLP projector - digital light projector
• DOE projector – an optical refractive element is placed in front of a light source, for example an LED, which creates a pattern of projected light.
• VCSEL – a very popular type of infrared laser today, the main advantage is the narrow, circular beam of light that is emitted perpendicularly from the projector, so it does not need additional rectification using lenses like the EEL laser. The accuracy is a little lower than other methods, but it is good for scanning dark and shiny surfaces, it is not so prone to noise, and it does not shine into the eyes when scanning a face. The VCSEL uses our peel 3 scanner. It is much easier to manufacture and has higher performance with lower power consumption. It finds application, for example, in the design of LIDAR in automotive.

Laser crosses

Today, blue lasers are used to ensure speed, quality and accuracy of scanning. Compared to red lasers, they ensure high-quality scanning of shiny and dark surfaces. HandySCAN 3D BLACK uses 11 laser lines and one line for hard-to-reach places, thanks to which it achieves such accuracy and quality of scanned data. The laser is class II, it is safe for the eyes.