Archive for the ‘Recent news’ Category

Primary Focusing Mirrors for Petawatt Laser Beamlines

Ultra-high precision off-axis paraboloids from Optical Surfaces Ltd. are being used to maximise power density at the focus of Petawatt laser beamlines run by world-leading, high-power laser research groups including ELI, LULI and CLF Rutherford as well as a growing number of academic centres of excellence.

Primary Focusing Mirrors for Petawatt Laser Beamlines

Off-axis paraboloid for high power laser focusing.

Off-axis paraboloids, also known as off-axis parabolic mirrors, are the focusing element of choice for high-power laser research groups because they offer the advantage of an unobstructed aperture and access to the focal plane. In addition, due to their completely achromatic performance, they are highly suitable for broadband or multiple wavelength applications.

Few optical manufacturers are able to produce off-axis paraboloids of sufficient surface quality to enable Petawatt lasers to focus their massive energy down onto targets only a few microns in size. Under these extreme conditions the laser-matter interactions can produce energetic beams of electrons and protons as well as bright, coherent sources of x-rays which enable researchers to address fundamental questions in areas including plasma physics, x-ray radiography, proton therapy and fast ignition experiments.

Using in-house production techniques developed over the last 50 years, and benefiting from a highly stable manufacturing environment largely immune from vibration and thermal variation, the company’s 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.

The company’s ISO 9001-2015 approved manufacturing workshops and test facilities 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 high precision mirrors, particularly with long path lengths, becomes quantifiable and reliable. In addition to these natural advantages, Optical Surfaces has invested in an extensive range of test equipment and have developed methods to ensure accurate and reliable testing.

To discuss development of an ultra-high precision off-axis paraboloid for your high-power laser facility please contact Optical Surfaces Ltd on +44-208-668-6126 or sales@optisurf.com.

For further information on off-axis paraboloids please visit www.optisurf.com/index.php/products/off-axis-paraboloids/.

Highly Efficient Fibre Optic Channel Plates

Optical Surfaces Ltd reports how it is machining and polishing high precision Fibre Optic Channel Plates (FOCP) for an X-ray shielding application.

Highly Efficient Fibre Optic Channel Plates

Schematic of a device using an FOCP to couple light onto an image sensor

Fibre Optic Channel Plates are widely used as optical devices to replace optical lenses because they require no focusing distance making them an ideal component when creating a compact optical device. Comprising a bundle of micron-sized optical fibres – FOCP are used as a lens to transmit light or an image with extremely high efficiency and low distortion. In each single fibre of a FOCP the light is transmitted by total internal reflection that occurs at the boundary between the core glass and the cladding glass due to the difference in their refractive index.

Fibre Optic Channel plates are widely used to couple light to solid state imaging devices such as CMOS and CCD image sensors. Used as the light receiving surface of an X-ray imaging device, the FOCP processed by Optical Surfaces Ltd is a key component preventing the image sensor in the camera from deteriorating due to exposure to X-rays.

To discuss your imaging application that may benefit from integration of a Fibre Optic Channel Plate please contact Optical Surfaces Ltd. on +44-208-668-6126 / sales@optisurf.com.

Large Diameter Reference Optical Flats

Optical Surfaces Ltd, a leading supplier of high precision reference optical flats to leading research establishments and national standards laboratories worldwide, reports on growing demand for larger (350 – 600mm clear aperture) diameters.

Large Diameter Reference Optical Flats

A large diameter reference optical flat being quality tested

Working with materials including ClearCeram®, Fused Quartz and Zerodur® in their unique thermally stable manufacturing environment – Optical Surfaces Ltd. is able to routinely achieve a surface accuracy of up to lambda/20 peak-to-valley and surface roughness of 10 Å rms on reference flats up to 650mm in diameter.

Dr Aris Kouris – Sales Director of Optical Surfaces Ltd commented “To enable us to quality test reference optical flats up to 650mm in diameter – we developed a 600mm Fizeau interferometer. This is a capability that only a few optical testing and manufacturing centres around the world possess. Housed in an ultra-stable testing environment, this interferometric set-up allows direct qualification of larger reference optical flats by testing them directly over their complete aperture without the need to use time-consuming combination methods. This in-house capability increases customer confidence in measurement accuracy and data analysis while minimising potential errors and the time taken to complete the quality testing. We believe this has been a key driver for the increased demand that Optical Surfaces Ltd has received to supply larger diameter reference optical flats”.

An optical flat is a precisely polished flat surface, used as a reference against which the flatness of an unknown surface or system may be compared. Reference optical flats are widely used in high precision applications in astronomy, inspecting gauge blocks for wear and accuracy as well as interferometric flatness testing of prisms, filters and optical windows.

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

** ClearCeram® is a registered trademark of O’Hara & Co. Ltd. and Zerodur® is a registered trademark of Schott AG.

New Polishing Technique Improves Finesse of Fabry Perot Etalons

Optical Surfaces Ltd. reports on the development of a new polishing technique that has been shown to reproducibly improve the spectral filtering capability (finesse) of Fabry Perot etalons.

For over two decades – Optical Surfaces has supplied precisely matched Fabry-Perot etalon pairs to Table Stable Ltd. (Mettmenstetten, Switzerland) for use as a key component in their ultra-high-resolution JRS Series interferometers.

Operating in a uniquely stable manufacturing environment, Optical Surfaces is able to produce the required 50-mm diameter fused silica Fabry Perot Etalons pairs with matching accuracies of better than lambda/200.

Precision Etalon Plates

Fabry Perot Etalons for ultra-high resolution interferometry

Dr Aris Kouris, Sales Director of Optical Surfaces said “Many parameters including material quality, optical figure, plate parallelism and coating quality are all critical to the overall performance of a Fabry Perot etalon. To maintain the competitive edge of the Table Stable Interferometer we are continuously investigating ways of further improving the quality of the matched Etalon pairs we supply to them. Our latest development project focused on how to improve the spectral filtering capability of the Fabry Perot etalon pairs by reducing surface ripples and microroughness. Our initial investigation using chemical polishing techniques brought some improvement, but degraded the matching accuracy of the etalon pairs. As a consequence, we refocused our efforts into developing new polishing techniques using conventional compounds. The results have been excellent – the new polishing technique has allowed us to almost eliminate surface ripples thereby improving the finesse of the Fabry Perot Etalons whilst maintaining all the other high-performance characteristics”.

For further information on ultra-high precision etalons for use in applications in interferometry, lasers and high-resolution spectroscopy please visit www.optisurf.com/index.php/products/etalons/ or contact Optical Surfaces Ltd. on +44-208-668-6126 / sales@optisurf.com.

Concave Spherical Mirrors for Schlieren Imaging

Drawing upon its uniquely stable manufacturing environment – Optical Surfaces Ltd. routinely produces the highest quality concave spherical mirrors for Schlieren Imaging systems in a range of materials including fused silica, Zerodur and ClearCeram.

Concave Spherical Mirrors for Schlieren Imaging

Concave spherical mirror for Schlieren imaging

Over the years – the company has produced concave spherical mirrors for Schlieren imaging applications looking at airflow turbulence, explosive shockwaves, gas leaks and visualisation of transparent thermal phenomena.

The skilled optical craftsmen at Optical Surfaces are experienced in producing concave spherical mirrors (up to 800mm in diameter) with surface accuracy of better than lambda/10 with particular emphasis on smoothness of the profile. Ultra high precision surface finish and durable optical coatings combine to provide superior Schlieren image quality.

Research and industrial groups acknowledge Schlieren imaging to be the preferred technique for visualising density variations in transparent media. In a typical Schlieren imaging set-up, a source directs light onto a long radius concave spherical mirror, which collimates the light and redirects it onto a second identical mirror. The resultant image may be captured by an imaging camera or on a screen.

For further information on ultra-high precision mirrors optimised for Schlieren imaging please visit www.optisurf.com/index.php/products/spherical-mirrors/ or contact Optical Surfaces Ltd. on +44-208-668-6126 / sales@optisurf.com.

Off-Axis Parabolic Mirrors Assist Accurate 3D Flight Tracking

Off-axis parabolic mirrors produced by Optical Surfaces Ltd

Off-axis parabolic mirrors produced by Optical Surfaces Ltd.

Optical Surfaces Ltd has been selected by the Optical Engineering Group at the University of Warwick (UK) School of Engineering to supply key focusing optics to enable accurate 3D tracking and analysis of mosquito flight behaviour.

The UK Engineering and Physical Sciences Research Council (EPSRC) funded research project at the University of Warwick will utilise large field-of-view digital holography for accurate 3D tracking of mosquito flight in an elongated flight chamber. Using this video-tracking methodology, researchers will look to accurately quantify the effects on mosquito behaviour of a range of chemicals or devices proposed to eliminate them, thereby providing a valuable insight into their mode of action.

Professor David Towers, Head of the Optical Engineering Group at the University of Warwick’s School of Engineering said “By capturing the diffraction pattern of mosquitoes in a telecentric volume, we can mathematically refocus the scene to obtain their z-axis positions, and therefore record a time-series of accurate 3D coordinates for tracking and analysing their flight behaviour. To facilitate this optical set-up, we required large aperture off-axis parabolic mirrors to provide the wide collimated beam required to examine a large field of view in an optical set-up that resembles a z-type Schlieren interferometer.”

Mosquito 2D flight patterns

Mosquito 2D flight patterns (courtesy: University of Warwick, Liverpool School of Tropical Medicine; Voloshin V, Kröner C, Seniya C, Murray GPD, Guy A, Towers CE, McCall PJ, Towers DP. 2020 Diffuse retro-reflective imaging for improved video tracking of mosquitoes at human baited bednets. R. Soc. Open Sci. 7: 191951. http://dx.doi.org/10.1098/rsos.191951)

Matthew Hall, the project researcher said “We approached Optical Surfaces to supply these key optics because of their international reputation for producing high quality off-axis parabolic mirrors. We have been impressed by the knowledgeable advice provided by Optical Surfaces and their flexibility to offer competitive pricing on an ex-stock off-axis parabolic mirror that meets our performance requirements”.

Dr Aris Kouris, Sales Director at Optical Surfaces Ltd. commented “We are very pleased to be involved in part of this important project to speed the development of new vector control products in the fight against malaria. We advised the Optical Engineering Group that they required an off-axis parabolic profile as it generates a collimated beam without obstruction of the optical path. The critical performance parameters for this application are the off-axis optical design, wide aperture and a good surface finish (< lambda/6) in order to produce a uniform phase-profile in the collimated beam. We look forward to seeing the results of this interesting research project". The work of the Optical Engineering Group at the University of Warwick School of Engineering is centred on performing basic and applied research in optical sensing technologies with applications across engineering, industry, the biological sciences and clinical practice. This research is frequently multi-disciplinary with active collaborations across these fields. For further information contact d.towers@warwick.ac.uk. Optical Surfaces Ltd. has been producing optical components and systems for leading academic and industrial research groups for more than 50 years. 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. 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 high precision off-axis parabolic mirrors please visit www.optisurf.com/index.php/products/off-axis-paraboloids/ or contact Optical Surfaces Ltd. on +44-208-668-6126 / sales@optisurf.com.

Optimistic Outlook at Optical Surfaces Ltd

Specialist high precision optics manufacturer – Optical Surfaces Ltd. (Kenley, UK) reports that despite the pressures of the global pandemic they managed to increase orders by 28% during 2020.

Highlights of the last year included being selected as the preferred optics supplier for two prestigious international projects, achieving on-time delivery to most existing customers and shipment of several complete systems which integrated precision optics and mechanics.

high precision optics

Dr Aris Kouris, Sales Director commented “Growth in 2020 came from the fundamental physics, aerospace, defence, environmental and medical sectors in particular who recognise our expertise in producing challenging one-off and small batches of optics and optical systems that deliver performance at the edge of what is possible”. He added “At Optical Surfaces we have achieved steady growth over the last few years and see opportunities to continue this positive trend moving forward. To deliver top quality, high precision optics in a timely fashion we have increased staff numbers by 15% over the last 3 years and plan to recruit more in 2021”.

Over the last 60 years – Optical Surfaces Ltd has established itself as a leading international manufacturer of top quality, high precision optical components and systems. Today the company supplies leading research labs and industrial organisations around the world with optical components and instruments including flats, spheres, aspherics, paraboloids, toroids, windows and mounts. Optical Surfaces Ltd is especially renowned for its expertise in large optics, beam expanders, collimators and prototypes.

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. 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 please visit www.optisurf.com or contact Optical Surfaces Ltd. on +44-208-668-6126 / sales@optisurf.com.Optimistic Outlook at Optical Surfaces Ltd

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.

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