General Optics

Variable-Radius Mirrors

Improve CO₂ laser cutting efficiency with this optic that enables dynamic focus depth adjustment and compensation for focal length variations across the working table.

The Variable-Radius Mirror is a unique component that permits beam divergence to be adjusted on-the-fly by varying the optic's radius of curvature with water or air pressure. They can be supplied in a large range of custom configurations.

Variable-Radius Mirror (VRM) Capabilities

Coherent employs proprietary design techniques to accurately model VRM shape, predict how it will deform under pressure, and optimize it for a specific application.

Typical Copper VRM Specifications

Pressurization Method 



Mirror Diameter

57.1 mm 

79.0 mm

Clear Aperture 

35 mm

50 mm 

Radii range

-6 m to 6 m 

3 m to Plano

Plano to 3 m 

1.2 m to -1.6 m

Pressurization Range 

3 to 12 bar

0 to 12 bar 

Angle of Incidence

Near normal 


Pointing Stability 

≤ 30 arc seconds


> 99.8% @ 10.6µm