Astronomical Research Drives Improvements in Optical Technology

Optical Surfaces Ltd. has published an article ‘Unveiling the Cosmos’ that discusses the latest challenges and trends in modern astronomy and describes how these advances have acted as a significant driver towards the improvement of their optical technologies.

Optical Technology

Using new high homogeneity optical materials and improved polishing compounds has enabled Optical Surfaces to make further improvements in their manufacturing of large space optics with very tight manufacturing tolerances. Combining this with the latest coating technologies the company is now able to deliver optical components with improved reflective / anti-reflective performance and enhanced environmental stability, protection and durability.

Over the last 50+ years, Optical Surfaces has established itself as is a leading designer and supplier of high precision astronomical optics operating over the entire spectral range from infrared to x-ray wavelengths.

Telescope primary mirrorBenefiting from operating in a unique production environment, free from vibration and temperature variation, Optical Surfaces Ltd is able to regularly produce high precision aspheric optics, ultra-smooth mirrors, high performance prisms, Schmidt camera and Laser launch telescope optics which stretch the limits of conventional optical fabrication techniques.

To certify the surface accuracy and precision of its astronomical optics, Optical Surfaces uses large aperture Zygo GPI, Twyman Green, Scatterplate, Fizeau and Laser Unequal Path (LUPI) interferometers which enables one-to-one testing of even the largest diameter astronomical optics. Topographic and fringe analysis provides precise testing of surface roughness and confirms the wavefront of various surface forms. A rolling program for calibration of test optics where possible to national standards and production approval to ISO 9001-2015 ensures that the quality of astronomical optics from Optical Surfaces is second to none.

To read the technical article in full please visit https://www.optisurf.com/index.php/unveiling-the-cosmos/. For further information on high precision astronomical optics please contact Optical Surfaces Ltd. on +44-208-668-6126 / sales@optisurf.com.

Precision Windows for High Power Laser Experiments

High Precision Laser Windows

Large, high precision laser window

Benefiting from an ultra-stable production environment and proprietary polishing techniques – Optical Surfaces Ltd. is able to routinely produce high-power laser windows up to 600mm in diameter with typical wavefront error of lambda/10 and surface finish of 40/20 to 10/5.

Working with a range of optical materials including BK-7 and fused silica, which offer good homogeneity and transmission from the UV to the Near-IR, Optical Surfaces is today a preferred supplier of large, precision windows to many high-power laser research groups around the world.

To optimise the performance of rapid-pulsed (femtosecond) high-power lasers – Optical Surfaces Ltd is able to supply the latest dielectric coatings on windows to provide minimum pulse distortion, maximum usable bandwidth and durability.

Large High Precision Laser Windows

Large, high precision laser window

In applications where there is significant risk of mobile material as a result of high-power laser ablation – Optical Surfaces also has considerable experience of producing large ultra-flexible windows (debris shields) to protect the final high precision lens that focuses laser energy onto the targets. Manufacturing debris shields combines the dual demands of producing a precision wavefront (typically lambda/5 to lambda/10) on a flexible window with a high diameter to thickness ratio.

For further information please visit https://www.optisurf.com/index.php/products/flats-and-windows/windows/ or contact Optical Surfaces Ltd. on +44-208-668-6126 / sales@optisurf.com.

Illustrated Guide to Aligning Off-Axis Paraboloids

Off-Axis Paraboloid Alignment ProcedureOptical Surfaces Ltd. announces that it produced an updated version of its popular ‘Practical Guide to Off-Axis Paraboloid Alignment Procedures’.

Off-axis paraboloids, also referred to as off-axis parabolic mirrors, provide the advantage of an unhindered aperture and access to the focal plane. They are ideal for broadband or multiple wavelength applications, thanks to their complete achromatic performance. Off-axis paraboloids often deliver the most cost-effective solution without compromising performance to many problems faced by optical and system designers.

With decades of manufacturing and supplying ultra-high precision off-axis parabolic mirrors to leading research groups around the world – the guide provides highly informed hints and tips to enable users to get top performance from their optics.

The illustrated alignment guide includes an introduction to OAP geometry as well as step-by step instructions on initial alignment; tips to correct for errors in focus and tilt, set off-axis distance and rotation and a final alignment procedure to ensure optimised performance.

For a copy of the 2018/2019 edition of ‘Practical Guide to OAP Alignment’ please visit www.optisurf.com/index.php/news/technical-tips/ or contact Optical Surfaces Ltd. on +44-208-668-6126 / sales@optisurf.com.

Next Generation Ellipsoidal Mirrors for X-Ray Diffraction

Optical Surfaces Ltd. is offering high-precision ellipsoidal mirrors that offer unmatched pinpoint focusing for high resolution spectroscopy in the soft and hard X-ray regions.

Ellipsoidal Mirrors

Ellipsoidal mirror for an XRD application

Drawing upon skilled craftsmen working in a uniquely stable production environment, Optical Surfaces is able to produce ultra-smooth ellipsoidal mirrors able to deliver an X-Ray Diffraction (XRD) spot that exactly matches your spectrometer detector resolution. As a consequence, the resolution and angular range of XRD measurements can simultaneously be improved. In addition, the pinpoint focusing provided by the ellipsoidal mirrors increases X-ray flux density, resulting in better contrast.

With workshops and test facilities deep underground where temperatures remain constant and vibration is practically non-existent, Optical Surfaces routinely produces ellipsoidal mirrors in a range of materials (Zerodur, BK7, fused silica) with typical surface accuracy of better than lambda/10 (dependent on size and radius) and surface quality of 20:10 scratch dig.

Optical Surfaces can produce ellipsoidal mirrors in a range of shapes (largest dimension up to 400mm) that offer high performance and durable optical coatings that provide excellent image quality.

For further information on high precision ellipsoidal mirrors for X-Ray Diffraction please visit https://www.optisurf.com/index.php/products/conic-sections/ellipsoids/ or contact Optical Surfaces Ltd. on +44-208-668-6126 / sales@optisurf.com

Improving Alignment & Testing of Earth Observation Satellites

High precision mounted reference mirrors

High precision mounted reference mirrors.

Optical Surfaces Ltd. has received an order from Surrey Satellite Technology Ltd. (SSTL) for two high precision reference mirrors to accelerate the precise alignment and testing of their Earth Observation Satellite Telescopes.

Based in Guildford, UK, Surrey Satellite Technology Limited (SSTL) manufacture and operate small to medium sized satellites, covering a range of use cases, from telecoms to Earth observation. Earth observation (EO) satellites are a core product for SSTL and each EO satellite undergo a rigorous process of testing and verification before and after launch. As SSTL’s business has grown it required additional high precision reference mirrors to enable testing of its telescope optical systems in parallel.

Dr Aris Kouris, Sales Director at Optical Surfaces Ltd said “We are pleased to have been entrusted once again by SSTL to deliver two demanding mounted reference flat mirrors for the purposes of verifying the wavefront performance of their EO telescopes during their assembly and as an alignment aid. The clear aperture of these mirrors was 300mm in diameter with a central hole of 100mm in diameter and the achieved surface accuracy was nearly L/15 P-V at 633nm. This target was particularly challenging since the mounted mirrors had to be tested in a ‘non-standard’ vertical orientation. Ensuring that the Lambda/15 p-v target was a true representation of the mirror required extensive testing and consequent adjustments in both, the testing as well as mounting strategy. During these tests all, possible sources of error were isolated, analysed and accounted for to confirm in a positive manner that the high specifications of the mounted mirrors supplied to SSTL were what we claimed them to be. Potential sources of error during the testing included intrinsic errors in our reference flat, mounting distortions on our reference flat and the UUT but also gravity effects on both the reference flat and the UUT. All these errors had to be disentangled and considered during the manufacturing process and we feel that we have done this in the best possible and most reliable way”. Dr Kouris added ” I can definitely say that we are extremely pleased with the outcome and being able to assist SSTL with their challenging alignment and testing requirements.”

An Earth Observation satellite being constructed

An Earth Observation satellite being constructed (courtesy: SSTL.)

Dr Robin Cole, Optical Systems Engineer at SSTL, commented “There are very few suppliers who can produce such large optics with the specifications we required. We had an additional requirement for a custom mounting configuration, for which Optical Surfaces Ltd. were able to propose and deliver a suitable design. We have worked with Optical Surfaces Ltd. on previous projects and have high confidence in their ability to deliver high specification optics on time and at a competitive price. From start to finish Optical Surfaces Ltd. operate a highly efficient and professional service, always engaging with enthusiasm and drawing on decades of experience to provide robust and innovative optical solutions”.

For further information about Earth Observation Satellite design and development at SSTL please visit https://www.sstl.co.uk/.

For further information on challenging optical systems for space research please visit https://www.optisurf.com/index.php/products/flats-and-windows/flats/ or contact Optical Surfaces Ltd. on +44-208-668-6126 / sales@optisurf.com

Beam Collimators for MTF Optical Testing

Beam CollimatorsOptical Surfaces Ltd is a leading supplier of Beam Collimators tailored to enable precise Modulation Transfer Function (MTF) testing of your optical systems.

MTF is a trusted technique for objectively evaluating the image-forming capability of optical systems. Reflective beam collimators are mirror assemblies that take divergent or convergent incoming light rays and produce parallel light output. They can be used to replicate a target at infinity without parallax. As a consequence, reflective beam collimators are the device of choice for performing polychromatic MTF measurements over extended wavelength ranges.

The high stability and performance of Optical Surfaces reflective beam collimators is achieved using a zero expansion off-axis parabolic mirror, manufactured to better than lambda/10 p-v surface accuracy. The optics within the beam collimator, are secured by the use of stress-free mounts and come pre-aligned for optimum performance. The off-axis design of Optical Surfaces beam collimators produces no central obscuration thereby ensuring highly efficient transmission is obtained.

The all-reflecting design of Optical Surfaces beam collimators is achromatic and with aluminium / magnesium fluoride coatings can operate from the UV to the infrared without adjustment. Using zero expansion glass mirror substrates these beam collimators provide exceptional operational stability. Each system has an output port datum plane giving a defined distance to the focus. All Optical Surfaces beam collimators provide a 20mm field ensuring full compatibility with standard black bodies.

A wide choice of options enables Optical Surfaces beam collimators to be tailored to exactly suit your MTF optical testing requirements. For further information on reflective beam collimators for MTF optical testing please visit www.optisurf.com/index.php/products/reflective-collimators/ or contact Optical Surfaces Ltd. on +44-208-668-6126 / sales@optisurf.com.

Challenging Aspheric Lenses for Nuclear Research

Optical Surfaces Ltd announces that it has received an order from the UK Atomic Weapons Establishment (AWE) for twelve ultra-fast focusing 370mm diameter aspheric lenses for its Orion petawatt laser research facility.

World-class expertise and cutting-edge science, engineering and technology lie at the heart of AWE work, spanning the life cycle of nuclear warheads from initial concept and design, to final decommissioning and disposal.

Challenging Aspheric Lenses for Nuclear Research

Image curtesy of AWE

The Orion laser facility is used to conduct research into high energy density physics phenomena, which occur at the heart of a nuclear explosion or the interior of a star. Orion is used to generate matter many times denser than solid, similar to that found at the centre of a giant planet such as Jupiter. At temperatures in excess of 10 million degrees, Orion can replicate conditions found at the centre of the Sun. These phenomena cannot be found anywhere else on planet Earth.

The order is a repeat order for the key focusing elements supplied by Optical Surfaces Ltd to AWE in 2008. Replacement of the original lenses is required as coatings and lens material gets damaged over time due to very high energy density of the Orion laser.

Dr Aris Kouris, Sales director at Optical Surfaces Ltd commented “We are very pleased to again be selected by AWE to supply the replacement fast focusing aspheric lenses that lie at the heart of their Orion petawatt laser facility”. He added “The greatest challenge in producing these ultra-smooth optics relates mostly with the high asphericity of the lenses, arising from the short focal length required. The short focal length not only enables AWE to use a relatively compact vacuum chamber for its experiments but also to achieve a very high energy density at the point of focus. This high asphericity also imposes an additional difficulty in controlling the demanding requirements associated with the lens wavefront gradients specification.

For further information about the Orion petawatt laser facility at AWE please visit http://awe.co.uk/what-we-do/science-engineering-technology/orion-laser-facility/

For further information on aspheric lenses for high energy laser research please visit https://www.optisurf.com/index.php/products/aspheric-lenses/ or contact Optical Surfaces Ltd. on +44-208-668-6126 / sales@optisurf.com

Athermalised Beam Expanders for Challenging Applications

For beam focusing applications in environments subject to wide temperature variation, Optical Surfaces Ltd. is able to produce athermalised beam expanders that deliver stable high performance.

Beam ExpandersOptical Surfaces athermalised beam expanders are based upon a Dall-Kirkham off-axis mirror design that incorporates INVAR elements to provide thermal stabilisation. In addition, to better control thermal behaviour, the off-axis mirrors in the athermalised beam expanders have a short focal length resulting in a very robust assembly which is less sensitive to temperature changes. As a result, high optical performance is maintained over a wide range of temperature (-40° C to +50° C).

Benefiting from an off-axis design, Optical Surfaces athermalised beam expanders provide an unobstructed output and highly efficient transmission. The reflective design of these beam expanders is achromatic and with aluminium coatings can operate from UV to far IR without adjustment or internal realignment. Each athermalised beam expander is housed in an aluminium housing with provision for fixing to an optical table. Alignment aids are provided to ensure correct beam pointing. Standard beam expanders have fixed magnification. Variable magnification beam expanders can be supplied with interchangeable primary mirrors. An interferogram and OPD map is supplied with every athermalised beam expander manufactured by Optical Surfaces.

For further information on athermalised beam expanders please visit click here or contact Optical Surfaces Ltd. on +44-208-668-6126 / sales@optisurf.com.

Off-Axis Paraboloids Enhance Laser Power Density

Optical Surfaces Ltd. reports on increased demand from high power laser research groups around the world for off-axis paraboloid mirrors to be used as the primary focusing element for their Petawatt laser beam lines.

Enhance Laser Power Density

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.

Using proprietary production techniques, and benefiting from a uniquely stable manufacturing environment, Optical Surfaces highly experienced and skilled engineering team are able to produce fast focusing off-axis parabolic mirrors with unmatched surface accuracy, surface quality and surface slope errors.

Dr Aris Kouris of Optical Surfaces Ltd commented “Few companies in the world are able to produce off-axis paraboloids of sufficient quality to enable Petawatt lasers to focus their massive energy down onto targets only a few microns in size. Laser-plasma interactions under these conditions can produce energetic beams of electrons and protons as well as bright, coherent sources of X-rays enabling researchers to address fundamental questions in astrophysics and plasma physics”.

Mounted Off-Axis Mirrors for Intense Laser Interaction Studies

He added “In recent years we are honoured to have been selected by world leading high power laser research groups including AWE, ELI, LULI and CLF Rutherford as well as a growing number of academic centres of excellence to provide key off-axis focusing mirrors and other related optics”.

For further information on off-axis paraboloid mirrors for high energy laser research please visit https://www.optisurf.com/index.php/products/off-axis-paraboloids/ or contact Optical Surfaces Ltd. on +44-208-668-6126 / sales@optisurf.com

OSL Optics to help unlock the secrets of Jupiter’s Icy Moons

Optical Surfaces Ltd. (OSL) announces selection by Hensoldt Optronics GmbH, formerly Airbus (Oberkochen, Germany) to supply key precision optics for optical testing the Ganymede Laser Altimeter (GALA), one of 10 scientific instruments on-board the JUICE (Jupiter Icy Moon Explorer) mission.

JUICE Mission of Jupiter

JUICE mission artist’s impression (courtesy: ESA)

The JUICE mission is part of the European Space Agency (ESA) cosmic vision programme and its objective is to study Jupiter’s plasma environment and the three icy moons Ganymede, Europa and Calisto. The JUICE spacecraft will be launched in 2022 on an Ariane 5 rocket. After its 8 year voyage it will enter an orbit around Jupiter. During the following three years the orbit will be gradually adjusted and after several fly-bys at Callisto, Europa and Ganymede the spacecraft will reach its final orbit around Ganymede. GALA will be used to determine the topography and time dependent shape of the moon by a direct laser altimetry approach.

UICE mission in Jupiter orbit

Strong electron field faced by JUICE mission in Jupiter orbit.

The GALA instrument is composed of three units: a transceiver unit, a laser electronics unit and an electronics unit all designed to withstand the challenging environment of Jupiter. At the heart of the transceiver unit is a lightweight Ritchey–Chrétien telescope incorporating precision optics capable of providing topographical vertical resolution of less than 5 metres and measure radial tidal deformations of the moons ice shell with an absolute accuracy of less than 0.03.

Because of its international reputation for supplying outstanding mounted optics for telescope systems and instruments, Hensoldt selected Optical Surfaces Ltd. to manufacture and supply a 550 mm diameter off-axis parabolic mirror and two identical folded flat mirrors (600 mm diameter) for optical verification testing of the Ritchey–Chrétien telescope in the GALA instrument.

Dr Aris Kouris, Sales Manager for Optical Surfaces Ltd. commented “To be chosen as a supply partner to help enable the JUICE mission is a great honour. Drawing upon our many decades experience in building telescope systems, we were able to propose a solution to overcome the considerable difficulties posed by the manufacture and testing of the high precision optics”.

For further information on high performance beam expanders please click here or contact Optical Surfaces Ltd. on +44-208-668-6126 / sales@optisurf.com.

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