Archive for the ‘Recent news’ Category

Speciality Prisms for Cryogenic Measurements of Refractive Index for ESO ELT’s Spectrograph – HARMONI

Optical Surfaces Ltd has received an order to supply the University of Oxford, UK with 3 speciality glass prisms for a study that will enable defining key components in the state-of-the-art HARMONI spectrometer being developed for ESO’s Extremely Large Telescope (ELT).

The ELT, a flagship project of the European Southern Observatory (ESO), will be the largest ground-based optical telescope ever built. Located in Chile, with a primary mirror of 39m diameter, ESO’s ELT, together with its HARMONI spectrometer, is expected to make a huge impact in astronomical observations of exo-planets, Solar System objects, stars, nearby and distant galaxies, quasars and other exotic objects.

CAD model of ESO's Extremely Large Telescope

CAD model of ESO’s Extremely Large Telescope (ELT) – Courtesy of ESO.

Being developed by the HARMONI consortium (jointly led by the Department of Physics at the University of Oxford (UK) and the UKATC), HARMONI is a visible and near-infrared (0.47 to 2.45 µm) integral field spectrograph, that will provide the ELT’s core spectroscopic capability, over a range of resolving powers from R~3000 to R~17000. HARMONI will offer a range of spatial pixel (spaxel) scales, to permit users to optimally configure the instrument for a wide range of science programs, from ultra-sensitive to diffraction limited, spatially resolved, physical, chemical and kinematic studies of astrophysical sources.

To achieve its potential, the optical design of the HARMONI spectrograph requires measurements of how refractive index changes with temperature (dn/dt) from room temperature (293K) right down to 70K. Getting data down to 70K is key because dn/dt is not a linear behaviour and varies from glass to glass.

Nicholas Cann – a Lead Optical System Engineer at RAL Space commented “HARMONI’s targets will be extremely faint, requiring the spectrograph optics to provide very high throughput and exquisite image quality at very fast focal ratios. This requires using new combinations of glasses, not previously used in cryogenic instruments.” He added “The FPL55, LAL8 and BAH28 prisms to be produced by Optical Surfaces are key to us gaining accurate cryogenic refractive index measurements all the way down to 70K for these three glass types. This will increase the knowledge of these glass types and permit their use, both by HARMONI and by other future projects. The prisms will be delivered to NASA Goddard Space Flight Centre in Maryland, USA where they have a purpose made testing facility called CHARMS. The measurement of each prism / glass with a number of wavelengths sources would take a long time, gradually lowering temperature in a controlled way and taking measurement at key points; mapping the dn/dt curve and the glass’s optical dispersion properties”.

Dr Aris Kouris – Sales Director at Optical Surfaces Ltd. commented “It is a real pleasure to have been given this opportunity to assist University of Oxford in their study. To have been entrusted to provide professional advice on matters associated with realisable manufacturing tolerances for some of the final HARMONI spectrograph optical components shows the respect our technical team has within the international Astrophysics community. Some of the glasses included in the current study are known to present certain difficulties with polishing. Consequently, careful consideration is required at this stage of the optical design to define what is achievable and what reasonable manufacturing tolerances may be”.

The Department of Physics of the University of Oxford is one of the largest physics departments in the UK. It has a strong track record in astronomical instrumentation, working together with the Science and Technology Facilities Council (STFC) laboratories (UK Astronomy Technology Centre (UKATC) and the Rutherford Appleton Laboratory (RAL Space)) on a variety of high-profile projects in ground- and space-based astronomy. Oxford Physics works with leading organisations worldwide, such as the European Southern Observatory (ESO), the European Space Agency (ESA) and NASA, to answer fundamental questions about the origins and evolution of planets and galaxies. It does this by contributing to the design and build of state-of-the-art instruments for many of the world’s major telescopes.

Optical Surfaces Ltd. has been producing optical components and systems for leading astrophysics research groups for more than 50 years. The company’s ISO 9001-2008 approved manufacturing workshops and test facilities are deep underground in a series of tunnels excavated in solid chalk where temperature remains constant and vibration is practically non-existent. With such stable conditions testing, particularly with long path lengths, becomes quantifiable and reliable. Working with these natural advantages is a highly skilled team of craftsmen with a commitment to excellence in both product quality and customer service.

For further information on demanding, high precision optics for astrophysics please contact Optical Surfaces Ltd. on +44-208-668-6126 / sales@optisurf.com.

Affordable, High Performance Beam Collimators

Optical Surfaces Ltd. announce a new series of high-performance beam collimators designed for Modulation Transfer Function (MTF) testing of optical systems.

Benefiting from a lightweight design and new assembly technique – the LW-series of beam collimators uniquely combine high stability, high performance and short delivery time all at a market competitive price.

High Performance Beam Collimators

LW-series beam collimators incorporate a low 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 LW-series beam collimators produces no central obscuration thereby ensuring highly efficient transmission is obtained.

The all-reflecting design of LW-series beam collimators is achromatic and with aluminium / magnesium fluoride coatings can operate from the UV to the infrared without adjustment. Using low expansion glass mirror substrates these beam collimators provide high operational stability and performance. Each system has an output port datum plane giving a defined distance to the focus. Each system is also supplied with an easy-to-use alignment aid to identify the centre of the focal plane. All LW-series beam collimators provide a 20mm field ensuring full compatibility with standard black bodies.

For further information on the LW-series of beam collimators for MTF optical testing please contact Optical Surfaces Ltd. on +44-208-668-6126 / sales@optisurf.com.

Durable Mirrors for High Power Lasers

Optical Surfaces Ltd. is a specialist producer of extremely durable, high performance coated mirrors, up to 600 mm in diameter, for use with high power femtosecond lasers.

Durable Mirrors for High Power Lasers

Durable coated mirrors for high power femtosecond lasers

Employing the latest dielectric coating technology, these high-power laser mirrors provide minimum pulse distortion and the maximum usable bandwidth. When used with high-power femtosecond lasers operating at 750 to 850 nm, Optical Surfaces mirrors are designed for use at power densities exceeding 1 J/cm2 for high frequency 50-fs pulses without deterioration.

Benefiting from a uniquely stable production and testing environment – Optical Surfaces skilled craftsmen routinely produce high power laser mirrors of the highest quality and precision. Produced from materials including glass, ceramic, and silica – Optical Surfaces off-axis parabolic mirrors are designed to optimise the performance of rapid-pulsed high-power lasers. All surface accuracies are checked by interferometer and are guaranteed to meet lambda/10 p-v wave accuracy with low scatter. The quality and performance of large diameter, high power femtosecond laser mirrors from Optical Surfaces Ltd. is second to none.

Typical applications for these extremely durable high-power femtosecond laser mirrors includes plasma physics, laser manufacturing and telecommunications.

To read a case study visit https://www.optisurf.com/index.php/optical-surfaces-delivers-parabolic-mirrors-for-petawatt-laser/ or for further information please contact the company on +44-208-668-6126 / sales@optisurf.com.

Optical Windows for Wind Tunnel Aerodynamic Testing

Optical Windows for Wind Tunnel Aerodynamic Testing

Large diameter, high precision optical window

Optical Surfaces Ltd is a producer of large diameter, high precision windows for wind tunnel aerodynamic testing.

Aerodynamicists and engineers use wind tunnels to test models of proposed aircraft and engine components. During a test, the model is placed in the test section of the tunnel and air is made to flow past the model. Schlieren imaging is a valuable technique to provide diagnostic information about the ‘invisible’ flow of air around the model.

Benefiting from an ultra-stable production environment and proprietary polishing techniques – Optical Surfaces Ltd. is able to routinely produce optical windows up to 600mm in diameter with typical wavefront error of lambda/10 and surface finish of 40/20 to 10/5. This precision manufacturing capability in optical materials including BK-7 and fused silica, which offer good homogeneity and transmission from the UV to the Near-IR, combines to provide the perfect wind tunnel optical window to ensure superior Schlieren image quality.

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

Highly Smooth Off Axis Parabolic Mirrors Offer Near 100% Reflectance

Highly Smooth Off Axis Parabolic Mirrors

Large steep angle OAP and small convex mirror produced by Optical Surfaces Ltd.

Optical Surfaces Ltd. reports that its off-axis parabolic mirrors are particularly suitable for coating using an Ion Beam Sputtering (IBS) technique that provides near 100% reflectivity thereby providing unmatched protection from thermal damage that often arises from high power continuous wave lasers.

Dr Aris Kouris, Sales Director of Optical Surfaces Ltd. explained “Surface microroughness of parabolic mirrors is an important optical quality parameter which describes features which are typically smaller than slope errors. Mirror surface microroughness, when pronounced, will cause effects that may be compared to mild scattering. For many applications such effects may not be so critical. However, for high power laser applications using off-axis parabolic mirrors as key focusing elements these effects can play an important role and therefore microroughness needs to be well controlled”. Dr Kouris added “We have undertaken a long-term study that shows that the proprietary pitch polishing techniques we use to finish off-axis parabolic mirrors produces unmatched low microroughness that do not exceed 1nm RMS. This is particularly important as only ultra-smooth off-axis mirrors can be regularly successfully coated using the ion beam sputtering (IBS) technique and attain nearly 100% reflectance and negligible absorption levels”.

Distribution of microroughness measurements

Distribution of microroughness measurements on OAPs produced using pitch-polishing technique

Off-axis parabolic mirrors (OAP’s) combine the achromatic and diffraction limited imaging properties of a parabolic mirror with the ability to deviate the light path off-axis, which is useful for most imaging systems. OAP’s offer the ability to focus collimated light without introducing spherical aberration. Additionally, unlike a centred parabolic mirror, an OAP mirror advantageously allows more interactive space around the focal point without disrupting the beam. OAP mirrors are especially suitable for broadband or multiple wavelength high power laser applications.

100% reflectivity produced by Ion Beam Sputtering technique

100% reflectivity produced by Ion Beam Sputtering technique

Using proprietary production techniques, and benefiting from a uniquely stable manufacturing environment, Optical Surfaces highly experienced and skilled engineering team are world renowned for producing fast focusing OAP mirrors with unmatched surface accuracy, surface microroughness and surface slope errors.

In recent years – Optical Surfaces 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 OAP mirrors and other related optics for a range of demanding high-power laser applications.

For further information on high reflectivity off-axis parabolic mirrors for high-power laser experiments please contact Optical Surfaces Ltd. on +44-208-668-6126 / sales@optisurf.com. To download a copy of the study ‘How microroughness impacts optical performance’ please visit www.optisurf.com/index.php/news/technical-tips/

Spectrograph to Record Near-IR Spectrum of Stars in a Single Exposure

Spectrograph prism

A Zinc Selendie (ZnSe) spectrograph prism

Optical Surfaces Ltd reports delivery to the Research Institute in Astrophysics and Planetology (IRAP) of high precision disperser prisms and folding mirror components that lie at the heart of the ground breaking SPIRou / SPIP near infrared spectrograph.

The SPIRou / SPIP spectrograph is designed to be able to record the whole near infrared spectrum of a star (over the wavelength range 0.98-2.35 µm and in either circular or linear polarization) on a 16-million-pixel Hawaii 4RG detector in a single exposure. In addition to being a spectropolarimeter, separating the light from stars into its elementary colours and vibration modes, SPIRou / SPIP is a high-precision velocimeter, capable of recording the tiny motions of a star that indicate the presence of an orbiting planet. As a consequence, the SPIRou/SPIP spectrograph will be used to also hunt for Earth-like planets orbiting in the habitable zones of nearby red-dwarf stars. IRAP (Toulouse, France) is one of the six laboratories which form the Midi-Pyrénées Observatory (https://www.omp.eu).

Yoan Micheau, a research engineer at OMP (Midi-Pyrénées Observatory), commented “Our innovative SPIRou / SPIP spectrograph is contained within a large cryogenic Dewar cooled down at a temperature of 77K (-200 °C) making it thermally stable to within a few millikelvin. To give us the best chance of recording faint astrophysics phenomena places great demand on the precision and accuracy of the spectrograph optics we use. Having successfully worked with Optical Surfaces Ltd on previous optically demanding projects it was an obvious choice to work with them again. I am very pleased to say that they have manufactured and delivered the large folding mirror and Infrasil / Zinc Selenide disperser prisms to the very demanding specifications (surface quality, transmission, wavefront error, scattered light and planarity) that we set”.

Dr Aris Kouris commented “Having supplied similar optics for the successful ESPaDOnS, FEROS and SPIRou projects, we have a proven record in manufacturing, mounting and testing precision optics for astrophysics projects”. He added “The high spectral resolution and performance that the SPIRou / SPIP spectrograph is designed to deliver can only be achieved by using optical components of the highest quality”.

The SPIRou / SPIP spectrograph contained within a large cryogenic dewar (courtesy:Midi-Pyrénées Observatory)

The scientific objectives of Midi-Pyrénées Observatory (https://www.omp.eu) are to study and develop understanding of the Universe including the Earth as a planet, its ionized environment, the sun and its planets, the stars and their planetary systems, the galaxies, the very first stars and the primeval Big Bang. The Midi-Pyrénées Observatory is acknowledged as a leading European centre of excellence in ground-space astrophysics.

Optical Surfaces Ltd. has been producing optical components and systems for leading astrophysics research groups for more than 50 years. The company’s ISO 9001-2008 approved manufacturing workshops and test facilities are deep underground in a series of tunnels excavated in solid chalk where temperature remains constant and vibration is practically non-existent. With such stable conditions testing, particularly with long path lengths, becomes quantifiable and reliable. Working with these natural advantages is a highly skilled team of craftsmen with a commitment to excellence in both product quality and customer service.

For further information on demanding, high precision optics for astrophysics please contact Optical Surfaces Ltd. on +44-208-668-6126 / sales@optisurf.com.

Light Weighted Mirrors

Light Weighted Mirrors

A light weighted mirror produced by Optical Surfaces Ltd.

Optical Surfaces Ltd has developed proprietary light weighting techniques that can reduce the weight of a mirror by as much as 60%.

In spaceborne applications the need to minimise payload is a key factor in designing optical systems. Optical Surfaces lightweight mirrors are designed to provide sufficient rigidity to ensure ultra-high precision optical performance while reducing the overall weight of the mirror. This reduced weight, in turn, allows smaller, lighter support and control structures, reducing the overall cost of optical systems such as space telescopes and spectrographs.

Light weighted mirrors also allow the creation of larger terrestrial telescopes and optical instruments than would be feasible with solid mirrors. Solid mirrors not only can be mechanically cumbersome, but are also difficult to cast and safely cool into a single, large block of optical glass.

Benefiting from a highly stable manufacturing environment and employing proprietary production techniques, Optical Surfaces highly experienced and skilled engineering team are world renowned for producing mirrors with unmatched surface accuracy, surface quality and surface slope errors. Working to strict ISO 9001-2015 guidelines all light weighted mirrors manufactured by Optical Surfaces Ltd are supplied with test data including high accuracy metrology, surface roughness and environmental data.

To discuss a light weighted mirror design to improve the performance of your telescope or optical instrument please contact Optical Surfaces Ltd. on +44-208-668-6126 or sales@optisurf.com.

Parabolic Mirrors for Optical Instruments

Parabolic Mirrors for Optical Instruments

An off-axis parabolic mirror produced by Optical Surfaces Ltd.

Optical Surfaces Ltd is a leading manufacturer of Off-Axis Parabolic Mirrors for optical instruments including radiometers, MTF measuring systems and spectrometers.

Off-axis parabolic (OAP) mirrors are the most common type of aspherical mirrors used in optical instruments because they are free from spherical aberrations, and can focus a parallel beam to a point or point source to infinity.

Employing off-axis parabolic mirrors in an instrument design allows optical engineers to not only minimise the size and weight of their system but also allows more interactive space around the focal point without disrupting the beam thereby increasing efficiency. OAP mirrors are especially suitable for broadband or multiple wavelength applications.

Benefiting from a uniquely stable manufacturing environment and employing proprietary production techniques, Optical Surfaces highly experienced and skilled engineering team are world renowned for producing off-axis parabolic mirrors with unmatched surface accuracy, surface quality and surface slope errors.

Optical Surfaces Ltd. has been producing top quality off-axis parabolic mirrors for more than 50 years and is widely accepted as one of the world’s leading manufacturers of these critical components for optical instruments.

Working to strict ISO 9001-2015 guidelines all off-axis parabolic mirrors manufactured by Optical Surfaces Ltd are supplied with test data including high accuracy metrology, surface roughness and environmental data.

To discuss an off-axis parabolic mirror design to improve the performance of your optical instrument please contact Optical Surfaces Ltd. on +44-208-668-6126 or sales@optisurf.com. For further information please visit www.optisurf.com/index.php/products/off-axis-paraboloids/

Optics and Optical Systems for Challenging Applications

Optical Surfaces Ltd is a leading manufacturer of high-precision optics and optical systems for challenging applications in areas including space research and high-power laser facilities investigating the frontiers of physics.

Broadband Collimator System

Motorised broadband collimator system now on-board the International Space Station

Using specialist production techniques, and benefiting from a uniquely stable manufacturing environment, Optical Surfaces highly experienced and skilled engineering team are renowned for producing ultra-smooth mirrors with unmatched surface accuracy, surface quality and surface slope errors.

Dr Aris Kouris of Optical Surfaces commented “Our pedigree in supplying state-of-the-art optics and optical systems for high power laser research is second to none. In recent years we have been selected by world leading high power laser research groups including AWE, ELI, LULI and CLF Rutherford as well as many academic centres of excellence to provide key mirrors and other related optics for a range of challenging applications”.

Hyperbolic mirror for deep space observation

Dr Kouris added “Producing high performance mirrors, lenses and spectrograph optics for space projects is something that we have done for many years. All optical components and systems to be used in space applications not only have to be lightweight but also have to meet certain key requirements to survive the harsh environment of space. They must be constructed of specific materials that will not outgas when exposed to the vacuum of space. All significant air spaces should be vented to avoid pressure on the elements and distortion of the lens. All materials right down to glues and greases must be approved and tested for outgassing”.

Very high precision focusing mirrors for the central laser facility at the Rutherford Appleton Laboratories (UK)

Optical Surfaces has been producing top quality optics for more than 50 years and is widely accepted as one of the world’s leading manufacturers of critical optical components and systems that are key to unlocking the secrets of the most challenging applications.

The company’s ISO 9001-2015 approved manufacturing workshops and test facilities are deep underground in a series of tunnels excavated in solid chalk where temperature remains constant and vibration is practically non-existent. With such stable conditions testing, particularly with long path lengths, becomes quantifiable and reliable.

In addition to producing precision optics and optical systems for challenging applications in high power laser physics and space research, Optical Surfaces Ltd also has considerable experience of supply for astronomical, healthcare, military and scientific research.

For further information or to discuss the optical requirements of your project please contact Optical Surfaces Ltd. on +44-208-668-6126 / sales@optisurf.com

Ultra-Stable Mounts for Optics & Mirrors

Optical Surfaces Ltd offer a range of high precision mounts developed to support off-axis paraboloids, spheres and optical flats up to 600mm diameter in applications where stability is important.

Ultra-Stable Mounts for Optics & Mirrors

Constructed in black anodized aluminium – four models of OS Mounts provide a secure and stable platform for mirror diameters from 100mm (4 inches) to 254mm (10 inches). Angular alignment can be made about two axes by means of dual action adjusters with fine screw and ultra-fine differential micrometre action. Using these mounts, it is possible to rapidly align a mirror within a few arc seconds. To facilitate rapid and simple mounting onto an optical table or other support each mirror mount comes with a baseplate.

For larger optics and mirrors – OS 300-600 mounts are available in four standard sizes to accommodate high precision mirrors from 305 mm (12 inches) to 550 mm (21.6 inches) in diameter. Angular alignment of mounted mirrors is achieved about the vertical and horizontal axes using dual action adjusters with fine screw and ultra-fine differential micrometre action. Using these mounts, it is possible to rapidly align a large diameter mirror within a few arc seconds. Each OS 300-600 mount comes with adjustable feet to facilitate rapid and simple mounting onto an optical table. A range of additional motorised options are available for OS 300-600 series mounts to enable remote operation in hostile environments or for use in limited space applications where manual adjustment may be difficult.

For mirrors over 550mm diameter – Optical Surfaces has facility and experience of providing ultra-stable mounts for such systems.

For further information on ultra-stable mounts to support optics and mirrors please visit www.optisurf.com/index.php/products/product-6/mounts-and-mounted-optics/ or contact Optical Surfaces Ltd. on +44-208-668-6126 / sales@optisurf.com

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