Polygons & Laser Scanning Systems

Polygon Scanning Mirrors

II-VI produces many types of Polygon Scanning Mirrors including Prismatic, Pyramidal and Irregular Polygons. Polygon Mirrors are diamond machined on our state of the art equipment to a variety of sizes ranging up to 300mm.

Facet-to-facet angle variation is a critical parameter in polygon performance and it can be split into two parts: the primary angle and the pyramidal angle. For example, the primary angle of a hexagon is 60° and 45° for an octagon. Variations in the primary angle will affect the timing between successive laser scans. Our process typically achieves less than 2 arcseconds facet-to-facet variation of the primary angle and ± 2 arcseconds overall accuracy. The pyramidal angle for most polygon mirrors is 90°. Variations of the pyramidal angle result in the beam shifting up and down between successive laser scans. Our process typically achieves less than 2 arcseconds facet-to-facet variation of the pyramidal angle.

Variation of the radial distance to each facet is another parameter that affects polygon performance. Depending on the optical layout, changes in the radial distance may shift the focal position of the laser beam above or below the target surface. Also in high speed applications, a variation in radial distance results in imbalance. Our process can maintain an overall radial distance range less than 5 microns.
Surface figure is important for maintaining a smooth scan as the beam traverses across a facet during polygon rotation. Our process produces surface figure as low as λ/8.

Surface finish quality will vary based on material.   With our process, 8 nm rms is typical on Aluminum 6061 and 5 nm rms is typical for OFHC Copper.  For the best possible surface finish (as low as 1 nm rms), Electroless Nickel Plating is recommend.  Also, if weight, high strength and stiffness are a design concern, Electroless Nickel Plated Beryllium and AlBeMet materials are good options.  In some applications, directional scatter from the orientation of the diamond machining marks may be a problem.  If this is a concern, we may be able to configure our process to orient the tool lines either parallel or perpendicular to the polygon’s axis of rotation.  Further improvements to surface finish can be gained through post-polishing techniques that can both reduce and randomize the surface microstructure.  Scratch/dig for diamond turned metal mirrors routinely meets 60/40 and some substrate materials enable 20/10 to be met.

Polygons, Prisms and Retro-reflectors

 

Laser Scanning Systems

F-Theta Lens

Laser Scanning Systems: F-Theta Lens

 

F-Theta lenses are commonly used in via-hole drilling, laser marking, and 3D printing. We design and build F-Theta lenses to customer specifications. Supply us with your system requirements listed in our datasheet so we can start your design!

 

Galvo Mirrors

Laser Scanning Systems: Galvo Mirrors

We produce build-to-print galvo mirrors for fast scanning applications in prototype and production quantities.  We typically diamond turn aluminum galvo mirrors and polish other materials such as silicon, SiC and glass.