Off-axis paraboloids offer the advantage of an unobstructed aperture and access to the focal plane. In addition, due to their completely achromatic performance, they are especially suitable for broadband or multiple wavelength applications.

OAPs often provide the most cost-effective answer without any compromise in performance and present the ideal solution to many problems to optical and system designers.


  • Collimators
  • Beam Expanders
  • FLIR testing
  • High power laser beam focusing
  • Target Projection
  • MTF reference surfaces
  • MRTD test systems
  • Spectrograph mirrors

Off-Axis Paraboloids Specifications

  • Up to 600mm in diameter
  • Non-circular shapes
  • Off-axis angles as large as 45 degrees
  • Surface accuracy up to lambda/20 at 633nm
  • Microroughness typically less than 1.2nm RMS
  • An extensive range of coatings available

Optical Surfaces has produced a A practical guide to Off-axis Paraboloid Alignment Procedure Click here to download…

Customer News Story

Optical surfaces has supplied two very high precision focusing mirrors for the Astra Gemini project at the central laser facility at the Rutherford Appleton Laboratories at Didcot in the UK.
The off-axis parabolic mirrors have diameters of 175mm a focal length of 285mm (an effective f ratio of 1.6) and an off-axis distance of 130mm. Despite the extreme aspheric nature of these mirrors, a surface accuracy of better than λ /15 P-V at 633nm, with slope errors of less than λ /10 per cm was achieved.
Another critical requirement, because of the colossal power of the beams, was a surface scratch dig of better than 20/10, which was comfortably met.
These mirrors are the critical beam focusing components that will help increase the intensity of the existing Astra laser by three orders of magnitude from 1019 W⋅cm-2 in a single beam to 1022 W⋅cm-2 on target in each of two beams.
The Astra Gemini project was funded by a CCLRC grant in a development that created the most intense laser in the world. The development provides the UK with a unique dual-beam facility, delivering a total power of 1 petawatt (1000 million million watts ). The development enables scientists to create and investigate extreme conditions in a controlled way in the laboratory. These conditions include temperatures as high as those found on the surface of the sun and colossal magnetic fields that are found in the polar fields of neutron stars.