Widest range of vacuum optics
Welcome to the vacuum optics division of Torr Scientific which offers the widest range of vacuum optics. Technicians in our established and growing glass shop manufacture glass‑to‑metal seals, tubulations, lead-free viewports and custom scientific glassware. Optical quality fused silica windows are vacuum brazed and leak tested with helium. Anti‑reflective coatings are designed and manufactured in‑house and can be optimised to customer wavelength requirements. Coating performance is optically tested in cleanroom conditions. Light, non‑magnetic and high optical quality vacuum windows are designed and manufactured for space satellite applications. Torr Scientific is also designing and manufacturing compact, non‑magnetic UHV chambers and laser window assemblies in collaboration with universities working in the world of ultra‑cold atom research and quantum technology projects. For further details, please use the Product Divisions menu.
Our
vacuum optic
products
Here you will find our main vacuum optics products
Brewster windows
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Available optics
Torr Scientific has incorporated optical quality windows into a wide range of viewports in response to growing demand from scientists carrying out laser experimentation within UHV systems. The company is also able to supply polished optics in a variety of forms and materials. Standard viewport windows can be offered as well as optics to custom specification. Precise surface qualities and optical specifications can be quoted.
Fused silica
Fused silica is a high‑purity synthetic silicon dioxide. This non‑crystalline and colourless silica glass has excellent optical qualities and broadband optical transmission through deep UV and visible to near infrared. Various anti‑reflective coatings to match customer reflectance requirements are designed and manufactured at TSL and can be offered on request.
Sapphire
Sapphire optics offer broadband optical transmission through UV and visible to near infrared. The single‑crystal sapphire optics have excellent optical, physical and chemical properties. The hardest of the oxide crystals, sapphire retains its high strength at high temperatures. Various anti‑reflective coatings to match customer reflectance requirements are designed and manufactured at TSL and can be offered on request.
Calcium fluoride (CaF2)
Calcium fluoride has widespread IR applications and is also useful in the UV, for example as UV excimer laser windows. Degradation due to moisture in the atmosphere is minimal and polished surfaces may be expected to withstand several years’ exposure to normal atmospheric conditions. Low solubility and wide transmission make this material useful for many applications. Special AR‑coated optics can be offered on request.
Kodial
Kodial, once a trade name, is a term used widely in the vacuum industry when referring to borosilicate glass (other trade names also exist, such as 8250 and 7056 glass). It is a rugged, general purpose, inexpensive window glass with good transmission from UV and visible wavelengths through to NIR. Its low coefficient of thermal expansion gives some resistance to thermal shock.
Germanium (Ge)
Germanium transmits fairly well between 2 µm and 14 µm and so is suitable for applications in thermal imaging and measurement. Its high refractive index (4 at 11 µm) gives it a high intrinsic reflectivity so that it can be used as a beamsplitter without special coatings. Components such as ATR (attenuated total reflection) heads for IR spectrometers are often made from germanium. It can also be used for electromagnetic shielding.
Silicon (Si)
Silicon is used as an optical material for wavelengths around 3 µm to 5 µm, such as in optical pyrometry, but also transmits well into the far IR and so sees use in THz applications. There are absorption bands between 6 µm and 30 µm that vary depending on the quality and manufacturing process, with high‑resistance float‑zone silicon generally absorbing the least.
Natural z‑cut quartz
The mineral quartz, which is a form of crystalline silicon dioxide, is birefringent unless light enters the crystal parallel to the optical axis, known as the z‑axis; z‑cut quartz has its optical axis perpendicular to the polished faces so that light entering at normal incidence is unaffected by birefringence. This z‑cut quartz is commonly used in optical applications. The material offers extended broadband optical transmission through deep UV and visible to near infrared.
CVD diamond
Chemical vapour deposition (CVD) processes have been developed to the point where economical synthetic diamond substrates are now readily available. The CVD diamond performance is close to or better than that of gemstone‑quality natural diamond, so customers can now take advantage of thermal conductivity that is five times that of copper, as well as high transparency for optical wavelengths that range from 225 nm to beyond 100 µm.
Magnesium fluoride (MgF2)
Magnesium fluoride transmits well into the VUV region. It is used mostly for UV optics and is excellent for excimer laser applications. Magnesium fluoride is a tough material and is slightly birefringent. Special AR‑coated optics can be offered on request.
Barium fluoride (BaF2)
Barium fluoride is used for applications in the IR and is often used as a viewport window for thermography. Barium fluoride cleaves easily and is susceptible to thermal shock.
Zinc selenide (ZnSe)
Zinc selenide optics are used widely as IR windows. Zinc selenide is one of the materials of choice for CO2 laser optics operating at 10.6 μm. Optics with anti‑reflective coatings can also be offered on request.
Zinc sulfide (ZnS)
Grown by CVD (chemical vapour deposition), zinc sulfide is usually polycrystalline and a rather opaque or translucent yellow colour. Tough and chemically resistant, it is suitable for use in harsh environments. As grown, it finds use in thermal imaging applications but with additional processing water is removed from the material, improving transmission at lower wavelengths and making the material optically clear.
KRS5 (thallium bromo-iodide, TlBrxI1‑x)
The thallium halide commonly known as KRS5 transmits from red light well into the deep IR. It has a deep red colour. It is widely used in IR spectrometry. KRS5 is generally chemically resistant but is toxic and requires basic handling precautions.
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Available coatings
AR anti‑reflective coatings
Torr Scientific offers fused silica viewports with an AR (anti‑reflective) coating on each face comprising a single quarterwave layer of coating material optimised for a customer‑specified wavelength range. Please advise the important wavelengths or wavelength range with your enquiry or order. Wavelength ranges between 190 nm and 1550 nm are offered as standard, although coatings for other wavelength ranges can be quoted on request.
VAR anti‑reflective coatings
Torr Scientific laser viewports are offered with a two‑layer V‑anti‑reflective (VAR, named for the shape of the reflectance curve) coating on both sides of the window optimised to a customer specified laser wavelength. The coating reduces reflectance to below 1% per face, or 2% total, at the wavelength specified. Please advise the laser wavelength with your enquiry or order. Wavelengths between 240 nm and 1550 nm are offered as standard, although coatings for other wavelengths can be quoted on request. Viewports with coatings for a wavelength range can also be offered.
WAR anti‑reflective coatings
Torr Scientific fused silica viewports are offered with a four‑layer W‑anti‑reflective (WAR, named for the shape of the reflectance curve) coating on both sides of the window optimised to customer‑specified laser wavelengths. In many cases, the coating reduces reflectance to below 1% per face, or 2% total, at the key wavelengths specified. Please advise the important wavelengths or wavelength range with your enquiry or order. Wavelength ranges between 240 nm and 1550 nm are offered as standard, although coatings for other wavelength ranges can be quoted on request.
Broadband anti-reflective coatings
Torr Scientific fused silica viewports are offered with a four‑layer broadband anti‑reflective (BBAR) coating on both sides of the window optimised to a customer-specified laser wavelength range. In many cases, the coating reduces reflection to below 1% per face or 2% total at the key wavelengths specified. Please advise the important wavelengths or wavelength range with your enquiry or order. Wavelength ranges between 240 nm and 1550 nm are offered as standard, although coatings for other wavelength ranges can be quoted on request.
A coating comprising a minimum of four layers applied to both faces to reduce reflection over a range of wavelengths. A BBAR is very much a compromise between the width of the range covered and the anti-reflective performance: as a design is tweaked to perform across a wider spectral range, the reflectance in the central wavelengths tend to increase (see plots). The achievable spectral range is narrower for short wavelengths than for longer.
Theoretical reflectance curves for a single BBAR-coated face of fused silica. As the wavelength range increases the reflectance gets poorer.
Other coatings or other materials are available on request.
Typical curves for the various coatings:
Example of sapphire:
Indium tin oxide (ITO) coatings
Torr Scientific also offers ITO (indium tin oxide) coatings.
The purpose of these coatings is to disperse the electrostatic charge from an optic. They are also highly chemically stable and durable, providing a good resistance to moisture/water penetration.
ITO has the unusual quality of being electrically conductive as well as optically transparent, which means it can dissipate charge on the optic without majorly impacting the transparency.
These coatings are available for all our standard viewports and can be paired with a lead disc insert for radiation protection in our Kodial/borosilicate range.
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