Off-Axis Beam Expander Enhances Performance of Doppler Wind Lidar

Optical Surfaces Ltd. has been selected by Beijing Metstar Radar Co., Ltd. (Beijing, China) to supply a high precision beam expander that will form a key component in their next generation fiber-based pulse Doppler Wind Lidar system.

doppler-wind-lidarBeijing Metstar Radar Co., Ltd. (Metstar) is a high-technology company formed in 1996 as a joint venture between the Lockheed Martin Corporation of the United States and China National Huayun Technology Development Corporation, a wholly owned subsidiary of the China Meteorological Administration. Metstar`s charter is to combine the latest technological advancements in both meteorology and electronics to provide high-class and reliable weather radars and services to the domestic and oversea customers and to branch out into related fields.

Dr. Zhifeng Lin, a senior research scientist at Metstar commented: “In meteorological Lidar systems, beam expanders are often used to magnify the laser beam to reduce its divergence in the far field. An off-axis reflective beam expander greatly reduces the blind zone of Lidar detection and therefore was considered as the best solution to this problem. In Lidar systems, such as Doppler Wind Lidar, the wavefront performance of the beam expander is very important for the Lidar efficiency. For instance only 1 dB loss in total efficiency is experienced when the RMS wavefront deviation of the beam is between lambda/10 and lambda/20, whereas an optical wavefront performance between lambda/5 and lambda/10 will result into a 3 dB loss. So, a well-designed beam expander system with wavefront performance better than lambda/20 RMS was specified as a critical component for our next generation Doppler Wind Lidar”.

Dr Lin added “These are the reasons why we choose a BEX series beam expander from Optical Surfaces Ltd for our fiber-based pulse Doppler Wind Lidar. These off-axis Laser Beam Expanders not only have no central obscuration and efficient transmission, but also have precision top quality surface accuracy of typically better than lambda/60 RMS (> lambda /10 PV). With this beam expander, alignment aids with sub-arcseconds repeatability are provided to ensure correct beam pointing. I am sure the BEX series beam expander from Optical Surfaces Ltd. will help enhance our Doppler Wind Lidar performance significantly”.

100mm aperture beam expanderDr Aris Kouris, Sales manager for Optical Surfaces Ltd. commented: “We are pleased to have received the order from Metstar which I believe will open a number of opportunities for further future collaborations. This is a challenging 100mm aperture Beam Expander based upon a Dall-Kirkham off-axis mirror design which, requires maintaining a high optical performance over a wide range of temperatures (-40° C to +50° C). In order to achieve this we are employing an INVAR rod solution together with a very high precision free-translating mechanism that exhibit, practically, negligible friction. In addition, in our efforts to better control the thermal behaviour, the off-axis mirrors have a short focal length resulting in a very robust assembly (the overall length expected to be around 0.5m) which is less sensitive to temperature changes, but makes the manufacturing of the highly aspheric primary and alignment a challenge as a result. Finally, the instrument has a relatively high magnification (M=20) that introduces further challenges during manufacturing, testing and assembly of the unit.”

For further information please contact Optical Surfaces Ltd. on +44-208-668-6126 / sales@optisurf.com. For further information on meteorological systems from Metstar please visit www.metstar.net.

Motorised Beam Reducers for Vulcan High Power Laser

Optical Surfaces Ltd. has received an order from the STFC Central Laser Facility** to supply 6 Motorised Beam Reducers for one of their high power laser target areas (Target Area West) on the Vulcan laser facility.

motorised-beam-reducers

The STFC Central Laser Facility (CLF) is one of the world’s leading laser facilities providing scientists from the UK and Europe with state-of-the-art laser technology. Vulcan is a versatile high power Nd: Glass laser system capable of delivering up to 2.6kJ of laser energy in long pulse mode (nanosecond pulses) and up to 1 PW (1015 W) peak power in a short pulse (500 fs duration). The CLF’s wide ranging applications include experiments in physics, chemistry and biology, accelerating subatomic particles to high energies, probing chemical reactions on the shortest timescales and studying biochemical and biophysical process critical to life itself.

An STFC spokesman commented “Target Area West uses 108mm diameter beam lines for the long-pulse delivery to target. There are 6 of these beam lines which operate at 1053nm with frequency doubling options to convert to 527nm. The diagnosis of these beams requires the beam diameter to be reduced by a factor of 10 following a leakage through a final turning mirror. The motorised beam reducers, to be supplied by Optical Surfaces Ltd for each of the beam lines, will allow operation in 2 modes. One to be used for continuous wave (cw) alignment and a second mode for “on shot” diagnostics with maximum of 1% transmission at 1053 and 527nm and beam energies of up to 50J at the input of the beam reducers. The mode switching makes their precise, high accuracy design and construction critical. The on-shot mode requires a carefully designed “dump” to prevent the high energy beam propagating and interacting with the transmitted output which would result in high background noise and stray reflections.

Dr Aris Kouris, sales manager for Optical Surfaces Ltd. commented “The project has posed significant design challenges for us both optically and mechanically. The main challenges were related to dimensional constraints, maintenance of pointing accuracy and repeatability when switching between the 2 modes, and designing the system to be able to deal with the high power densities involved during the on shot diagnostics mode. The Beam Reducer will be based upon a Dall-Kircham off-axis mirror design with a number of folding mirrors between the primary and secondary. A final periscope pair at the output allows the input and output to be co-axial and maintain centre height for in-line operation. The switching between the 2 modes is achieved by two “switched” folding mirrors operated by an Optical Surfaces developed mechanism that will allow a high degree of repeatability of the order of just few arc seconds. This will allow maintenance of high optical performance and pointing accuracy during operation. Furthermore, the 2 mirrors are located in a position that will allow the coating to be able to withstand the energy densities present during the on-shot diagnostic operation and before attenuating the beam to suitable levels. Selection of appropriate coatings was also a great challenge and specific coating limitations greatly dictated the final optical design”.

Optical Surfaces Ltd has been producing optical components, mounted optical components and systems for more than 50 years and is now accepted as one of the world’s leading manufacturers of high-precision optics and optical systems for High Power laser applications. 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 high precision optics and mirrors for high power lasers please visit www.optisurf.com/index.php/products/off-axis-paraboloids/ or contact Optical Surfaces Ltd. on +44-208-668-6126 / sales@optisurf.com.

* Image (copyright: STFC)

** Further information at www.stfc.ac.uk/clf/Facilities/Vulcan/Vulcan%20experimental%20areas/13886.aspx

Concave and Convex Spherical Mirrors

Optical Surfaces Ltd. is a leading international supplier of concave and convex spherical mirrors made to your exact specification.

A spherical mirror is a mirror which has the shape of a piece cut out of a spherical surface. Spherical mirrors of various radii and diameters have been supplied by Optical Surfaces to organisations worldwide for over 50 years. High precision spherical mirrors produced by Optical Surfaces have been used in a huge variety of applications including Schlieren imaging, Wind tunnels, Observatory spectrographs, Bubble chambers and, as Hindle spheres, to test hyperboloids.

spherical mirrors

A 1.3-metre diameter spectrograph spherical mirror was supplied to the Royal Greenwich Observatory and was installed on the 2.5-metre Isaac Newton Telescope located at La Palma on the Canary Islands. The spectrograph contributed to obtaining the first observable evidence of the existence of black holes.

With workshops and test facilities deep underground where temperatures remain constant and vibration is practically non-existent Optical Surfaces routinely produces high precision spherical mirrors in a wide range of materials and coatings. Typical achievable surface accuracy is better than lambda/30 p-v, surface quality 10:5 scratch dig and micro roughness less than 1.2nm RMS. These same unique production facilities allow Optical Surfaces to manufacture and test very long radii spheres by taking full advantage of the long tunnels we have at our disposal.

Optical Surfaces ISO 9001-2000 approved manufacturing facility provides the flexible resources to supply from single specialist requirements to OEM quantities. Benefiting from its stable environment, quality testing becomes quantifiable and reliable. All spherical mirrors are provided with a complete quality test assurance report.

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

Aspheric Parabolic Lenses and Mirrors

Using proprietary production techniques – Optical Surfaces Ltd has established itself as a market leading supplier of demanding aspheric parabolic lenses and mirrors mirrors with off-axis angles approaching 30 degrees and focal lengths as short as 100mm.

In addition benefiting from a uniquely stable manufacturing environment the company is routinely able to produces highly aspheric, fast focusing (to f 0.7) on-axis parabolic mirrors.

With its team of skilled technicians and engineers, Optical Surfaces Ltd is also able to fabricate high performance aspheric lenses with tight tolerances. Excellent performance is assured through production of aspheric lenses with excellent surface quality – low surface scatter (20-10 scratch-dig) and high surface accuracy (lambda/20).

Off-Axis Parabolic MirrorsThe requirement for aspheric mirrors and lenses is particularly prevalent in space-borne optical systems, astronomical telescopes and the next generation of very high power laser systems. Driven by the high cost of launching payloads into space – considerable demands are placed upon reducing the size and weight of optical systems. Many of the designs for the new generation of astronomical telescopes use a segmented spherical primary mirror coupled with highly aspheric mirrors in order to compensate for the primary spherical aberration. To achieve the highest laser power densities – fusion researchers require the highest achievable optical throughput combined with pinpoint focusing capabilities. The realisation of these optics, due to the required large aspherisation, is a real technical challenge for optical manufacturing.

aspheric-lensesThe complex surface profile of aspheres offers excellent correction of spherical aberration and reduce other optical aberrations compared to a simple lens or mirror. A single aspheric lens or mirror can often replace a much more complex multi-element system. The resulting device is smaller and lighter, and sometimes cheaper than the multi-element design. On-axis parabolic mirrors produce collimated reflected light and are used in applications that require very fast focusing and high energy densities. 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 broadband or multiple wavelength applications due to their completely achromatic performance.

Optical Surfaces ISO 9001-2000 approved manufacturing facility provides the flexible resources to supply from single specialist requirements to OEM quantities. Benefiting from its stable environment, quality testing becomes quantifiable and reliable. All toroidal mirrors are provided with a complete quality test assurance report.

For further information please visit www.optisurf.com/index.php/products/aspheric-lenses/ or www.optisurf.com/index.php/products/off-axis-paraboloids/ or contact Optical Surfaces Ltd. on +44-208-668-6126 / sales@optsurf.com

High Precision Toroidal Mirrors

Optical Surfaces are a leading international supplier of high precision toroidal mirrors (toroids) made to your exact specification.

High Precision Toroidal Mirrors

Toroidal mirrors are normally used where a beam needs to be focused or folded. The design of toroidal mirrors eliminates astigmatism normally caused by concave spherical mirrors. Toroidal mirrors are widely used for correction of aberration in a range of applications served by spectroscopic instruments, monochromators and imaging devices that require pinpoint focusing.

With workshops and testfacilities deep underground where temperatures remain constant and vibration is practically non-existent Optical Surfaces routinely produces toroidal mirrors in a range of materials (Zerodur, BK7, Fused Silica) with typical surface accuracy of better than lambda/5 (dependent on size and radius) and surface quality of 20:10 scratch dig. Working with a comprehensive inventory of advanced testing techniques – Optical Surfaces can produce both Plano-convex and Plano-concave toroidal mirrors in a range of shapes (largest dimension up to 400mm) with high performance and durable optical coatings that provide superior image quality.

Optical Surfaces ISO 9001-2000 approved manufacturing facility provides the flexible resources to supply from single specialist requirements to OEM quantities. Benefiting from its stable environment, quality testing becomes quantifiable and reliable. All toroidal mirrors are provided with a complete quality test assurance report.

For further information on high precision toroidal mirrors please visit www.optisurf.com/index.php/products/toroids/ or contact Optical Surfaces Ltd. by telephone on +44-208-668-6126 or via email sales@optsurf.com.

Miniature Reflective Beam Expanders

New smaller diameter (25 – 60mm) Reflective Beam Expanders have been introduced by Optical Surfaces Ltd. for space restricted applications such as for high power lasers and multi-wavelength interferometry.

Miniature Reflective Beam Expander

OSL reflective beam expanders are aspheric mirror-based devices offering either beam expansion or reduction capabilities. Incorporating high precision off-axis mirrors, OSL reflective beam expanders provide an unobstructed output and highly efficient transmission. By comparison, due to dispersion, lens-based beam expanders are only capable of compensating for focus at one wavelength of light, making them only suitable for expanding/reducing monochromatic sources. Reflective beam expanders use mirrors which have constant focal lengths, regardless of the light being focused. Thus, reflective beam expanders can be used with collimated polychromatic light without the need of any fine focus adjustment.

Available in standard (2.5x, 5x, 10x fixed magnification) or customer specified (fixed or variable magnification) configurations – OSL smaller diameter reflective beam expanders are designed to be easy to use and to provide accurate, unobstructed expansion / contraction of any collimated input light source. Optical Surfaces reflective beam expanders are portable and can be used without the need for internal re-alignment.

Each OSL reflective beam expander is supplied housed in aluminium housing with provision for fixing to an optical table. Alignment aids are provided to ensure correct beam pointing. Manufactured to better than lambda/5 surface accuracy, the off-axis design of these reflective beam expanders produces no central obscuration and highly efficient transmission is obtained, unspoilt by spider diffraction patterns. An interferogram and OPD map is supplied with every reflective beam expander manufactured by Optical Surfaces Ltd.

Optical Surfaces Ltd has been producing optical components and systems from its ISO 9001-2000 approved manufacturing facility for more than 50 years and are today accepted as one of the world’s leading manufacturers of reflective beam expanders.

For further information on smaller diameter reflective beam expanders please contact Optical Surfaces Ltd. on +44-208-668-6126 / sales@optisurf.com

Custom Optical Mounts for Challenging Applications

Optical Surfaces Ltd. has been supplying custom modified versions of its high precision optical mounts (custom optical mounts) for challenging applications for over 20 years.

Custom MountsDrawing upon the knowledge of skilled engineers and optical designers – Optical Surfaces is able to provide an optical mount design service that delivers an optimised solution for your application. Typical custom modifications include mounts for non-circular optical components and for supporting larger diameter optics (> 600mm). Various motorised mount options are also available to suit applications in hostile environments (under vacuum, elevated temperature, high pressure) or where limited space makes manual adjustment difficult. As an option to the standard 2-axis gimbal micrometer-driven action, Optical Surfaces mounts can be fitted with x-y-z linear stages if required. This addition allows the user to accurately control positioning of optical components in up to 5-degrees of freedom.

Optical Surfaces standard range of OS mounts were developed to support optics and mirrors such as off-axis paraboloids, spheres and flats in applications where stability is important. Constructed in black anodized aluminium – OS mounts provide a secure and stable platform for optical components with diameters from 100mm to 550mm. Angular alignment can be made about two axes by means of dual action adjusters with fine screw and ultra-fine differential micrometer action. Using these mounts it is possible to rapidly align an optical component or mirror within a few arc seconds. To facilitate rapid and simple mounting onto an optical table or other support each OS mount comes with a base plate.

For further information please visit click here or contact Optical Surfaces Ltd by telephone on +44-208-668-6126 or email sales@optisurf.com.

Fast Focusing Mirrors for High Energy Physics and Astronomy

Generations of customers have benefited from incorporating high precision on-axis parabolic mirrors from Optical Surfaces Ltd. into their optical systems.

With a heritage stretching back over 50 years, to the production of large astronomical telescope optics in excess of 1 metre diameter, Optical Surfaces is today recognised as one of the world’s leading producers of on-axis paraboloids for applications in high energy physics and astronomy.

Using proprietary production techniques and benefiting from an ultra-stable production environment – Optical Surfaces highly experienced and skilled engineers can, depending on the surface accuracy required, generate very fast focusing on-axis parabolic mirrors ( < f 0.7).

Fast Focusing Mirrors for High Energy Physics and Astronomy<br />

In comparison to an off-axis mirror design, the f-number achievable with an on-axis parabolic mirror is higher therefore more energy can be concentrated. Other advantages of on-axis parabolic mirrors are that generally, alignment is less critical, thus easier and for the same apparent f-number an on-axis parabolic mirror will be less expensive.

On-axis parabolic mirrors are especially suitable for broadband or multiple wavelength applications due to their completely achromatic performance. A range of coatings is available from Optical Surfaces including metallic (with or without protective overcoat), multilayer dielectric and ultra hard coatings for high-power lasers.

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

Space Observation Optics Cover from IR to X-ray Wavelengths

Optical Surfaces Ltd is a leading designer and supplier of high precision, ground telescope and satellite-based space observation optics operating over the entire spectral range from infrared to x-ray wavelengths.

optical-surfaces-image

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

Investment in large aperture Zygo GPI, Twyman Green, Scatterplate, Fizeau and Laser Unequal Path (LUPI) interferometers allows one-to-one testing of even the largest diameter space observation optics. Topographic and fringe analysis provides precise testing of surface roughness and confirms the wavefront of various surface forms. A rolling program for calibration of test optics where possible to national standards and production approval to ISO 9001-2000 ensures that the quality of space observation optics from Optical Surfaces Ltd. is second to none.

Notable projects assisted by Optical Surfaces’ high precision optics include the UV Optical Telescope on the NASA Swift Explorer mission; the XMM Optical Monitor telescope for the European Space Agency (ESA); a Cassegrain camera for the NigeriaSat-2 satellite and the HROS Spectrograph for the 8m Gemini telescope (Chile). Visit www.optisurf.com/index.php/news/application-stories/ for details of these and other projects.

For further information on high precision space observation optics and optical systems please contact Optical Surfaces Ltd. on telephone on +44-208-668-6126 / email sales@optisurf.com.

Precision Interferometer Optics Help Push the Boundaries of High Resolution FT-IR

Optical Surfaces Ltd. has been selected by a leading spectrophotometer manufacturer to supply ultra high precision matched beamsplitter / compensator optics for the interferometer that lies at the heart of its High Resolution FT-IR system.

gimbal-mirror-mounts-z-series

To achieve this outstanding performance Optical Surfaces is manufacturing the 100mm diameter OA grade fused silica beamsplitter and compensator optics with a surface accuracy of lambda / 20 (p-v) and wavefront error in transmission of lambda / 20 (p-v) at 633nm. Further each beamsplitter / compensator pair is tightly matched in thickness and wedge angle.

Dr. Aris Kouris, sales and marketing manager at Optical Surfaces Ltd. commented “High resolution spectroscopy places great demands on being able to achieve leading edge specifications with the interferometer optics. Being selected to produce the optics at the heart of the FT-IR system was based upon our proven pedigree in reliably producing ultra high precision optics for a growing number of spectrometer and interferometer manufacturers”.

Optical Surfaces Ltd (www.optisurf.com) has been producing optical components and systems for more than 50 years and is now accepted as one of the world’s leading manufacturers of high-precision optical systems for spectroscopic and interferometric applications. 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 relating to high precision optics and optical systems for spectroscopy and interferometry please contact Optical Surfaces Ltd by telephone on +44-208-668-6126 or email < href="mailto:sales@optisurf.com">sales@optisurf.com.

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