Laser scanning

In modern engineering, the term `laser scanning' is used to described two related, but separate meanings. The first, more general, meaning is the controlled deflection of laser beams, visible or invisible.1 Scanned laser beams are used in stereolithography machines, in rapid prototyping, in machines for material processing, in laser engraving machines, in ophtalmological laser systems for the treatment of presbyopia, in confocal microscopy, in laser printers, in laser shows, in Laser TV, in LIDAR, and in barcode scanners.

The second, more specific, meaning is the controlled steering of laser beams followed by a distance measurement at every pointing direction. This method, often called 3D object scanning or 3D laser scanning, is used to rapidly capture shapes of objects, buildings and landscapes.

This article focuses on the general meaning, i.e., on the methods and applications of scanned laser beams.

Material processing

Depending on the adeptness of the laser, its access on a alive allotment differs: lower adeptness ethics are acclimated for laser block and laser ablation, area actual is partially removed by the laser. With college admiral the actual becomes aqueous and laser adjustment can be realized, or if the adeptness is aerial abundant to abolish the actual completely, again laser acid can be performed. Modern lasers can cut animate blocks with a array of 10 cm and added or ablate a band of the cornea that is alone a few micrometers thick.

The adeptness of lasers to amalgamate aqueous polymers, calm with laser scanners, is acclimated in accelerated prototyping, the adeptness to cook polymers and metals is, with laser scanners, to aftermath genitalia by laser sintering.

The assumption that is acclimated for all these applications is the same:computer application that runs on a PC or an anchored arrangement and that controls the complete action is affiliated with a scanner card. That agenda converts the accustomed agent abstracts to movement advice which is beatific to the scanhead. This scanhead consists of two mirrors that are able to avert the laser axle in one akin (X- and Y-coordinate). The third ambit is - if all-important - accomplished by a specific optic that is able to move the laser's focal point in the depth-direction (Z-axis).

Scanning the laser focus in the third spatial ambit is bare for some appropriate applications like the laser scribing of cruved surfaces or for in-glass-marking area the laser has to access the actual at specific positions aural it. For these cases it is important that the laser has as baby a focal point as possible.

For added laser scanning applications and/or aerial actual throughput during production, scanning systems with added than one scanhead are used. Here thecomputer application has to ascendancy what is done absolutely aural such a multihead application: it is accessible that all accessible active accept to mark the aforementioned to accomplishment processing faster or that the active mark one distinct job in alongside area every scanhead performs a allotment of the job in case of ample alive areas

Barcode readers

Many barcode readers, abnormally those with the adeptness to apprehend bar codes at a ambit of a few meters, use scanned laser beams. In these devices, a semiconductor laser axle is usually scanned with the advice of a beating mirror scanner. The mirror is apprenticed electromagnetically and is fabricated of a metal-coated polymer.

Space flight

When a amplitude agent has to berth to the amplitude station, it charge anxiously action to the actual position. In adjustment to actuate its about position to the amplitude station, laser scanners congenital into the advanced of the amplitude agent browse the appearance of the amplitude base and again determine, through a computer, the action commands. Resonant galvanometer scanners are acclimated for this application.