Understanding Laser Scanners

When complex or large environments need to be documented, Laser Scanners provide a practical and economical solution. 

Traditionally, capturing large environments relied on tools that produced single point measurements, such as tape measures, piano wire, plumb bobs, laser range finders and total stations. While they are familiar tools, they are often time-consuming, often taking days, weeks or months depending on the space. Additionally, traditional tools often produce inconsistencies in measurements from user to user and ultimately data often get missed, leading to potentially cascading inaccuracies.
In contrast, Laser Scanners are non-contact devices that capture millions of discrete data points to measure an object or space using laser infrared technology that produces detailed 3D images in minutes. The images comprise millions of 3D data points, known as a point cloud.
So, how do they accomplish all of that so quickly? The Laser Scanner emits a beam of infrared laser light onto a rotating mirror that effectively paints the surrounding environment with light. The scanner head rotates, sweeping the laser across the object or area. Objects in the path of the laser reflect the beam back to the scanner, providing the geometry that is interpreted into 3D data. In addition to the distance measurement, Laser Scanners also capture measurements on the horizontal and vertical planes, providing a full scope of measurement data.  
A Laser Scanner typically captures data through two kinds of systems:
Time-of-flight systems: Also known as a pulse measurement system, this works by emitting a single pulse of laser light and determining the distance to the end point by measuring the time it takes for the light to be reflected back to a sensor on the scanner.
Phase-shift systems: Similarly, this system also uses an emitted laser light, but in this system, the intensity of the light is modulated with specific wave forms. The reflection of the intensity patterns is displaced by the impact on the surface of the object. Measuring the displacement between the sent out and the received laser signal provides a precise distance calculation. Generally, Laser Scanners that use phase-shift systems are accurate, fast and provide high-resolution data.