High Precision Prisms and Beamsplitters

Optical Surfaces Ltd is a leading supplier of single to OEM quantities of high precision, custom beamsplitters to a growing number of spectroscopy, interferometry and imaging instrument manufacturers around the world. The optimal beamsplitter can take on many forms including cubes, plates, hexagons, pentagons, polarizing, non-polarizing or wedge designs in a wide variety of reflection / transmission ratios and substrates depending upon your application.

Optical Surfaces also manufactures high quality prisms to customer supplied specifications in quantities ranging from prototypes, through batch runs to production quantities. Operating in a uniquely stable manufacturing environment – Optical Surfaces has experience of producing all types and configurations of prism (amici/roof, bi-Fresnal, corner cube retroreflectors, dove, equilateral, isoceles, penta, rhomboid and wedge) with market- leading tolerances. Available as single components (up to 450mm) or cemented units – Optical Surfaces routinely achieves angle accuracy of better than 2 arc seconds, surface accuracy of lambda/20 p-v, 10/5 surface quality and microroughness of less than 1.2nm rms..

Optical Surfaces welcome users’ inquiries. Customers can rely on Optical Surfaces' five decades of experience and craftsmanship which guarantees to meet clients' applications and meet or surpass their specifications.



  • Size ranges up to 450 mm
  • All types and configurations are taken into account
  • Angle precision better than 2 arc seconds
  • Surface accuracy of λ/20 P-V at 633 nm
  • Single or cemented
  • Microroughness normally less than 1.2 nm RMS
  • Engineering and mounting service
  • Comes with an extensive range of coatings
  • Surface Quality: 10/5


  • Measures up to 500 mm diameter
  • Non-circular shapes are available
  • Surface accuracy of λ/20 P-V at 633 nm
  • Surface Quality: 10/5
  • Engineering and mounting service
  • Microroughness is normally less than 1.2 nm RMS
  • A wide range of coatings available

Fiber Optic Channel Plates (Filters and Fibers)

  • Parallel to 0.010 mm
  • All profiles available
  • Stain-free

Customer News Story - Prisms

Optical Surfaces Ltd. has previously provided the Niels Bohr Institute with a pair of ultra-high precision counter-rotating doublet prisms for the Atmospheric Dispersion Corrector (ADC). These were a key component of the instruments used in the SONG project.

The SONG project is a collaboration between researchers at the Department of Physics and Astronomy, University of Aarhus, and the Niels Bohr Institute, University of Copenhagen. SONG is the acronym for Stellar Observations Network Group and the objective of the project is to develop an observatory consisting of a network of telescopes distributed throughout the planet.

The SONG telescope design aims to meet two scientific targets: it must quantify stellar oscillations that can probe the internal structure of stars, and it must be able to identify Earth-like planets in the Milky Way.

Reflecting on their choice of supplier, Per Kjærgaard, SONG Project Manager, commented: “Optical Surfaces Ltd was selected to produce the critical ADC prism doublet because of their impressive track record in preparing high-performance optical systems for telescope and space projects.”

High Precision Prisms and Beamsplitters

Image Credit: Optical Surfaces Ltd.

Optical Surfaces also provided two prisms with an entrance face measuring around 250 mm for the FEROS spectrograph, installed in the European Southern Observatory in Chile.

The prism was a crucial component of the project.

In spite of the concerns with respect to the possibility for such a huge prism in obtaining the wavefront needed, both manufactured prisms were completely compliant with the requested specifications.

After the prism faces were polished, the results were examined and it was discovered that additional local figuring was required to correct for glass internal irregularities. On completion, the wavefront had completely met the customer specification.

A spokesperson for the organization stated that the transmitted wavefront had even surpassed their specification and applauded Optical Surfaces for doing such an “excellent job.”

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