Optical Surfaces Ltd has supplied a high precision beamsplitter that lies at the heart of a Michelson type interferometer for testing of optical components used in military applications.

The Defence Systems integrator awarded the contract to design and build the interferometer selected Optical Surfaces Ltd as their optical supply partner for this project because of their track record in producing complex, high precision optics.

Required for testing the quality of infrared optical components the Michelson type interferometer design was optimised for multi-wavelength operation in both the mid and far infrared.

Dr Aris Kouris, Sales Director at Optical Surfaces Ltd. commented “The beamsplitter is one of the most critical components of an interferometer as it divides a beam of light into two distinct paths and then recombines the two beams after introducing a difference in the two paths. Operating in a uniquely stable manufacturing environment our team of experienced optical craftsmen were able to produce an ultra-high precision finish (Lambda/20 p-v) on all surfaces of the beamsplitter. However, to produce the multi-wavelength operation required a big stack of dielectric coatings on the partially reflective side of the beamsplitter which caused the surface form to be distorted. To overcome this challenge – we quantified the amount of costing induced distortion and then applied the opposite amount of distortion when recoated to produce the required high performance optical form”.

Optical Surfaces Ltd is a leading supplier of single to OEM quantities of high precision, custom beamsplitters to spectroscopy, interferometry and imaging instrument manufacturers around the world. For further information on custom beamsplitters please visit www.optisurf.com/index.php/custom-beamsplitters/ or contact Optical Surfaces Ltd. on +44-208-668-6126 / sales@optisurf.com.

Optical Surfaces Ltd has launched a new low profile mounting system that provides a highly stable platform for smaller diameter (up to 75mm) parallel or wedge backed off-axis parabolic (OAP) mirrors.

Designed to facilitate rapid and simple mounting onto an optical table or other support, Optical Surfaces is now able to supply smaller diameter OAP mirrors pre-aligned in the new high quality stress-free mount.

Benefiting from a uniquely stable manufacturing environment, and a highly skilled team of engineers and craftsmen, Optical Surfaces has established itself as a world leader for the production of high precision off-axis parabolic mirrors. The company is able to routinely produce OAP mirrors with surface accuracy to lambda/20 (peak-to-valley) depending upon off-axis angles. Using proprietary polishing techniques Optical Surfaces can, depending on the surface accuracy required, achieve the natural limit to the off-axis angle of around 25-30 degrees and surface micro-roughness of less than 1 nm. A range of coatings is available for standard and custom components from metallic with or without protective overcoat to multilayer dielectrics and ultra-hard coatings.

Unlike standard parabolic mirrors, off-axis parabolic mirrors direct and focus incident collimated light at a specific angle, allowing unrestricted access to the focal point as well as reducing the size and minimising the weight of an optical design.

For further information on mounted, smaller diameter off-axis parabolic mirrors please contact Optical Surfaces Ltd on +44-208-668-6126 or sales@optisurf.com.

Optical Surfaces Ltd is a leading manufacturer of high precision hyperbolic mirrors that are used in satellite-based telescopes to collect and focus light enabling high-resolution remote observation in applications including agriculture, water resources, urban planning, rural development, mineral prospecting, environment, forestry and disaster management.

Earth observation satellites employ hyperbolic mirrors in their telescope design to allow high optical performance over a large field-of-view in a compact footprint. A hyperbolic secondary mirror is used in Cassegrain telescopes to effectively balance aberrations caused by the shorter focal length of a typically parabolic primary mirror. In addition, in some more extreme low f/ratio applications served by Ritchey-Chretien telescopes, both the primary and secondary mirrors may be hyperbolic.

Drawing upon a uniquely stable production environment – Optical Surfaces skilled optical engineers are able to produce secondary convex hyperbolic mirrors up to 150mm diameter with typical wavefront error of only lambda/20 P-V, surface finish of 10/5 and microroughness of less than 1.2nm RMS. Such customer specified ultra-smooth hyperbolic mirrors can be supplied with a coating exactly optimised for your application. In space borne telescope platforms, where weight is an issue, Optical Surfaces can also produce hyperbolic mirrors with light-weighting options.

For further information relating to hyperbolic mirrors for satellite-based telescope systems please visit www.optisurf.com/index.php/products/conic-sections/hyperboloids/ or contact Optical Surfaces Ltd. on +44-208-668-6126 / sales@optisurf.com.

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.

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/.

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

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.

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.

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.

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.

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.

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.

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.

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.”

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.

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.

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