Telescope System for Zettawatt Equivalent Laser

Optical Surfaces Ltd has been selected by the Gérard Mourou Center for Ultrafast Optical Science (CUOS) at the University of Michigan (USA) to provide beam expander optics for its ground-breaking Zettawatt-Equivalent Ultrashort pulse laser System (ZEUS).Sponsored by the U.S. National Science Foundation, the ZEUS laser facility is being constructed to allow a Petawatt laser pulse from one of its beamlines to collide with a beam of GeV-energy electrons generated by its other beamline. In this collision, the electrons will encounter a Zettawatt (1021 watt) equivalent laser power as measured in their rest frame.

Telescope System for Zettawatt Equivalent Laser

CUOS researchers performing multidisciplinary research on the applications of ultrashort laser pulsers (courtesy; University of Michigan).

John Nees, a research scientist at CUOS said “The construction of the ZEUS facility began in 2020 and is slated to be operational in 2024. Among its numerous challenges, the Chirped-Pulse Amplified (CPA**) laser system requires an ‘aberration-free’ telescope to deliver the fully amplified pulses at a safe fluence to the 3 Petawatt compressor where their power is increased 50,000-fold for experimental use. The telescope comprises a 170 mm diameter convex aspheric mirror and a 255 mm positive spherical mirror used in an off-axis design. As a leading manufacturer of ultra-high precision Petawatt laser optics we selected Optical Surfaces Ltd. to fabricate the precision mirror substrates that will be coated and used to expand the pulsed beam diameter from 140 mm to 305 mm”. He added “I really did appreciate Optical Surfaces energetic responses to my inquiries as I was planning the telescope. Their knowledgeable input gave me a good comfort level in moving the project forward”.

Director of Sales at Optical Surfaces Ltd. – Dr Aris Kouris commented “We are honoured to be selected by CUOS as the supplier of high precision beam expander for this prestigious project. With this ZEUS laser system, the CUOS team is excited about the possibility of probing quantum electrodynamics, the reigning explanation of how the universe operates at the subatomic level. In addition, ZEUS could help develop new methods and technologies for use in medicine, defence, material science and astrophysics”.

Off-axis beam expander optics (courtesy: Optical Surfaces Ltd)

Off-axis beam expander optics.

Globally, only a few optical manufacturers can produce off-axis optics as part of the delivery system of sufficient surface quality to enable ultra-high-power lasers to focus their massive energy 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 can produce fast-focusing off-axis 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.

For further information on the pioneering work of the Gérard Mourou Center for Ultrafast Optical Science (CUOS) at the University of Michigan visit https://zeus.engin.umich.edu/. To discuss development of ultra-high precision optics for your high-power laser facility please contact Optical Surfaces Ltd on +44-208-668-6126 or sales@optisurf.com.

** The invention of the Chirped Pulse Amplification (CPA) laser system was the basis for awarding the 2018 Nobel Prize in Physics to Gérard Mourou and Donna Strickland. See https://www.nobelprize.org/prizes/physics/2018/summary/

Large Optical Windows for Military Sensing Applications

Optical Surfaces Ltd is an established manufacturer and supplier of large-area windows of optical quality for military sensing applications.

Optical windows are a critical component in a variety of defence applications including aerial surveillance, reconnaissance and targeting. For over 50 years – Optical Surfaces Ltd has been working with materials including fused silica, BK-7 and Germanium to produce defence grade windows up to 600mm in diameter.

Large Diameter Reference Optical Flats

A large diameter reference optical flat being quality tested

Typically, large diameter optical windows for defence applications are used to provide
environmental protection for sensitive internal sensing systems. To transmit light with minimal disruption, these large diameter optical windows must exhibit low surface roughness, minimal transmitted wavefront errors, and high transmission at the desired operational wavelength range.

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

Dr Aris Kouris – Sales Director of Optical Surfaces Ltd commented “To enable us to quality test large diameter optical windows – 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 large diameter optical windows by testing them directly over their complete aperture without the need to use time-consuming combination methods”.

For further information on large diameter windows for military sensing applications 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.

Infrared Collimators for performance testing of Thermal Cameras

Optical Surfaces Ltd. is a leading supplier of off-axis parabolic and flat mirrors, the key optical elements in Infrared (IR) collimators commonly used for evaluating the performance of thermal imaging systems.

Infrared Collimators for performance testing of Thermal CamerasThe function of an IR collimator is to generate a thermal image closely resembling the thermal scene at a test plate. Performance tests often performed on Thermal Imaging systems include measurement of the Minimum Resolvable Temperature Difference (MRTD) and the Modulation Transfer Function (MTF). The importance of MRTD testing lies in the fact that it relates to a thermal imaging system’s effectiveness for discerning details in a scene. MRTD values provide estimates of resolution capability allowing comparison of one thermal imaging system with another. The MTF is a tool for optical designers to quantify the overall imaging performance of a system in terms of resolution and contrast. Knowledge of the MTF curves of the lenses and camera sensors involved in a thermal imager may be used for quantification and optimization of the system performance.

Parabolic mirrors are the most common type of aspheric used in optical instruments. They are free from spherical aberrations, and therefore can focus a parallel beam to a point or a point source to infinity. Off-axis parabolic mirrors provide an unobstructed aperture allowing complete access to the focal region as well as reducing the size and minimising the weight of a design. They are especially suitable for infrared waveband applications due to their completely achromatic performance. Using proprietary polishing techniques, the team of experienced engineers and craftsmen at Optical Surfaces Ltd. can routinely produce a surface accuracy of better than lambda/20 p.v. and surface roughness of less than 1nm on off-axis parabolic mirrors produced for IR Collimators.

Working with high-stability materials such as Fused Quartz and Zerodur, in a unique thermally stable manufacturing environment, Optical Surfaces Ltd can routinely achieve a surface accuracy of better than lambda/10 p.v. and surface roughness of less than 1nm on flat mirrors. Over the years – Optical Surfaces has developed expertise to mitigate the uncertainties associated with coating to ensure flatness of mirrors, and hence is able to improve the performance of flat mirrors used in IR Collimators.

For further information on ultra-smooth off-axis parabolic and flat mirrors for high performance IR Collimator systems contact Optical Surfaces Ltd. on +44-208-668-6126 / sales@optisurf.com.

Large Diameter Optics, Mirrors & Optical Mounts

Optical Surfaces Ltd is an established supplier of large diameter mirrors, optical flats, windows, lenses, beam expanders and collimators to leading research establishments worldwide.

Typically, such large diameter elements need to be made as custom optics, because they are required either as single prototypes, or in small numbers, and are often subject to demanding manufacturing tolerances.

Program of Investment

Large diameter, ultra-high precision mounted mirror

Benefiting from a unique thermally stable manufacturing environment and working with high-stability materials such as Zerodur and Fused Silica, Optical Surfaces can routinely achieve a surface accuracy of better than lambda/10 p.v. and surface roughness of less than 1nm rms on reference flats and optical windows up to 600mm (24-inches) in diameter.

Aspherical mirrors are the one of most common type of element used in beam expanders, collimators, interferometers, astronomical instruments and as key focusing elements on ultra-high power laser beamlines. Using proprietary production techniques – Optical Surfaces has established itself as a world-leading producer of large diameter parabolic mirrors with a surface accuracy of better than lambda/20 P-V and smoothness of 20/10 scratch/dig. Combining this excellent surface quality with a range of high reflectivity coatings enables researchers to achieve the leading-edge optical performance and efficiency required by even the most demanding experiments.

The OS 300-600 series of large-diameter mirror mounts from Optical Surfaces Ltd. are designed to provide a secure platform for larger, high-precision flat, spherical and off-axis mirrors in stability-critical applications. Robustly designed in black anodized aluminium, the mounts are available in four standard sizes to accommodate high-precision mirrors from 305 to 550 mm 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. These mounts make it possible to rapidly align a large diameter mirror within a few arc seconds.

Optical Surfaces Ltd has been producing large diameter optical components and systems 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.

For further information on large diameter mirrors, optical flats, windows, lenses, beam expanders and collimators please contact Optical Surfaces Ltd. on +44-208-668-6126 / sales@optisurf.com.

Wideband Infrared Beamsplitter for Military Testing

 Wideband Infrared Beamsplitter for Military TestingOptical 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”.

 Wideband Infrared Beamsplitter for Military Testing

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.

Versatile Mounting System for Off-Axis Parabolic Mirrors

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.

Versatile Mounting System for Off-Axis Parabolic Mirrors

Each small diameter mounted off-axis parabolic mirror comes in a protective carrying case

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.

Hyperbolic Mirrors for Earth Observation Satellites

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.

Hyperbolic secondary mirror

Hyperbolic secondary mirror

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.

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.

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