Posted in | News | Optics and Photonics

Extremely large reference flat for testing space optics

Optical Surfaces Ltd. has received an order from JEEWOO Photonics Ltd (Daejeon, South Korea) to produce a 700mm diameter reference flat - a key component in an optical test system being developed for a space optics organisation.

700mm diameter reference flat

700mm diameter reference flat. Image Credit: Optical Surfaces Ltd.

The optical test system is required for aligning and testing long focal length, large aperture multi optical component systems without degrading optical quality.

Benefiting from an ultra-stable production environment and employing proprietary polishing techniques – Optical Surfaces Ltd. can routinely produce large diameter reference flats with typical wavefront error of up to lambda/20 p-v, surface roughness of less than 10 Å rms and surface finish of 40/20 to 10/5 scratch / dig.

Asked why he had selected Optical Surfaces Ltd as a partner for this prestigious supply contract – Mr MoonWhe Hur, director of JEEWOO Photonics said “There are few optics manufacturers in the world able to produce optics of such size and with the specialised test equipment to demonstrate conformance to the ultra-high precision finish specification. Over the years we have worked closely with Optical Surfaces Ltd on a series of demanding optical development projects which because of their highly skilled staff have all been successful with deliveries kept to time”.

Dr Aris Kouris – Sales Director of Optical Surfaces Ltd commented “We were delighted again to be selected by JEEWOO Photonics as a supply partner. The production of the large CLEARCERAM®-Z reference flat is well underway, we hope to move onto final polishing and testing soon. To enable us to quality test large diameter reference – we developed a large aperture Fizeau interferometer. Housed in an ultra-stable testing environment, this interferometric set-up allows direct qualification of large diameter reference flats by testing them directly over their complete aperture.

For further information on large diameter reference flats please visit or contact Optical Surfaces Ltd. on +44-208-668-6126 / [email protected].

For further information on JEEWOO Photonics Ltd please visit

The ISO 9001-2015 approved manufacturing workshops and test facilities at Optical Surfaces Ltd are deep underground in a series of tunnels excavated in solid chalk. This provides an environment where temperature is naturally thermally stable, and vibration is extremely low. With such stable conditions testing of all beam collimators becomes quantifiable and dependable. In addition to these natural advantages, the company has invested in an extensive range of test equipment and uses trusted methods to ensure accurate and reliable testing of surface accuracy, quality, and slope errors.


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