Laser scanning

To control the scanning motion, scanners need a rotary encoder and control electronics that provide, for a desired angle or phase, the suitable electric current to the motor (for a polygon mirror) or galvanometer (also called galvos).

Two-dimensional systems are essential for most applications in material processing, confocal microscopy, and medical science.

There are also microscanners, which are MEMS devices containing a small (millimeter) mirror that has controllable tilt in one or two dimensions; these are used in pico projectors.

When two optical lenses are moved or rotated against each other, a laser beam can be scanned in a way similar to mirror scanners.

By taking a distance measurement at every direction the scanner rapidly captures the surface shape of objects, buildings and landscapes.

The principle that is used for all these applications is the same: software that runs on a PC or an embedded system and that controls the complete process is connected with a scanner card.

This scanhead consists of two mirrors that are able to deflect the laser beam in one level (X- and Y-coordinate).

The third dimension is - if necessary - realized by a specific optic that is able to move the laser's focal point in the depth-direction (Z-axis).

Here the software has to control what is done exactly within such a multihead application: it is possible that all available heads have to mark the same to finish processing faster or that the heads mark one single job in parallel where every scanhead performs a part of the job in case of large working areas.

Many barcode readers, especially those with the ability to read bar codes at a distance of a few meters, use scanned laser beams.

Laser light shows typically uses two galvanometer scanners on an X-Y configuration to draw patterns or images on walls, ceilings or other surfaces including theatrical smoke and fog for entertainment or promotional purposes.

Laser scanning module with two galvanometers, from Scanlab AG. The red arrow shows the path of the laser beam.
A high speed mobile laser scanning system for 3D data acquisition mounted on an automobile.
A high speed mobile laser scanning system for 3D data acquisition mounted on an automobile.