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Knight Optical(UK) Ltd - [email protected] - +44 (0)1622 859444


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We supply a range of optical windows in a selection of materials to meet all scientific instrument applications from UV-Visible and NIR wavelengths. We stock different grades dependent on application, from high quality precision N-BK7 or equivalent type with flat and parallel faces for imaging applications to simple white float windows for general purpose instrument applications.

Plastic windows: Knight optical supply a range of custom plastic windows to meet a range of UV-Visible and NIR applications. Custom plastic windows are typically used for low cost instrument panel applications. Plastic marks and scratches easily so an anti-scratch coating is normally applied which helps prevent degrading of the surfaces. Typical custom plastic window products we supply are:
PMMA acrylic windows which have excellent transmission properties though the Visible and NIR wavelengths. It has uniform thickness, minimal double image refraction and is available with anti-scratch coatings for improved performance.

Anti-glare acrylic windows which are finely etched on one of the surfaces which create a very fine diffused finish preventing reflections of light in the visible and NIR wavelengths. Custom Anti-glare windows are used in typical applications to enhance lettering on displays and to sharpen images. Both acrylic uncoated windows and anti-glare type windows are available with anti-scratch coatings on for increased performance and are available in 0.2, 0.3, 0.4, 0.5, 0.8, 1.0, 1.5, 2.0, 3.0, 4.0 and 5mm thk. Other custom thicknesses are available on request.
Anti-reflective coated acrylic windows are coated with multilayer antireflective coatings on one side of both sides. These custom AR coated acrylic windows have no double images reflections and are typically used in LCD displays, instrument panels and bar code scanners.

Domes: Knight Optical’s ranges of custom domes are available in a variety of materials. Currently we offer BK7 or equivalent, UV Fused Silica, Sapphire and Acrylic domes, in a range of diameters and thicknesses. A dome is an optical window composed of two parallel curved surfaces. Knight Optical’s custom polished domes range in diameter from 5 to 500mm, with thicknesses from 10mm down to just 0.25mm thick. Custom domes are primarily used in defence applications, often in extreme environments. For this reason, our custom domes offer both high transmission as well as durability. Other applications for our custom domes include visible-range domes for pyranometers and infrared-range domes for pyrgeometers.

Precision grade N-BK7 or equivalent windows: Our stock range of precision grade BK7 or equivalent windows are used to seal optical enclosures especially suited to low power laser applications. Our stock range of ¼ wave BK7 or equivalent windows are uncoated and also AR coated both faces with extended BBAR for visible and NIR applications (450-900nm) We are also soon to introduce a range that offers increased performance in the telecom region of 1100-1700nm. These stock BK7 or equivalent windows have very parallel faces so will introduce minimal beam deviation. Flatness and surface quality is also tightly controlled. Stock BK7 plates can be edged down to smaller diameters and custom sizes at short notice. Our stock BK7 or equivalent windows can also be AR coated for other wavelengths, beamsplitter coated or mirror coated to meet your bespoke custom requirements.

Borosilicate  or equivalent windows: We offer two grades of stock borosilicate windows “float grade borosilicate windows” which are cut from standard float sheet material and “polished grade borosilicate windows” which are further polished to better flatness and surface quality. Our stock ranges are made from Low Expansion Borosilicate or equivalent glass. Borosilicate or equivalent has excellent transmission over the visible and NIR wavelengths working from 310nm to 2700nm. Low-expansion Borosilicate (LEGB) or equivalent Windows are very useful as windows in many harsh applications because borosilicate or equivalent glass has excellent chemical and thermal-shock resistance and has a maximum working temperature of 500°C so are excellent for use in high powered light source applications or an excellent choice for cold and hot mirror substrates.   Borosilicate or equivalent windows can also be a good substrate for optical flats as it has low expansion properties and therefore maintains its flatness in different environmental conditions.

Float glass windows: Soda-lime float windows are cost effective medium performance windows however they have limitations transmitting around 80% average from 400-700nm with poor performance in NIR. Soda-lime float glass is a sheet material that is relatively flat.

Soda-lime float glass windows are excellent for use in standard non-scientific window applications such as protecting visible CCTV camera or windows for picture framing applications and flat panel displays. They are also an excellent substrate for optical mirrors as transmission properties are not important. Low-iron type Float glass window material is also used for a standard “dip coated” AR coating window we stock which is ideal for lower specification low reflection applications where small residual reflection is required. This range of standard low-iron white float windows work efficiently across the visible into the near infrared region.

B270 or equivalent windows: B270 or equivalent windows work efficiently from 320nm though to 2600nm with average transmission of 90% from 400nm to 2000nm. B270 or equivalent glass is a sheet material that is relatively flat. It comes as manageable sheet sizes of 258x406mm in a large range of standard thicknesses. As B270 material comes in standard thickness it is ideal for cost effective scientific window applications as BK7 or equivalent requires sawing and polishing processes that add to costs.

Quartz/ UV fused silica & IR quartz windows: We stock a range of Quartz, UV fused silica and IR fused quartz windows for applications in the UV though to the near infrared regions.

Quartz windows can be used at temperatures up to 1050°C and has a high average transmission of over 80% from 260nm to 2500nm. Our stock ranges of quartz windows are useful for most UV applications other than fluorescence applications as quartz material fluoresces. Our stock quartz windows are also not useful in wavelength applications less than 250nm where transmission drops to just 72%. For deep UV at 175-185nm UV fused silica is a more suitable choice of material.
UV grade fused silica windows Our stock range of UV fused silica windows are made from Corning 7980 grade 2G, which is the equivalent of Spectrosil 2000 also referred to as Spectrosil B. UV grade fused silica windows have excellent UV transmission working efficiently at 175nm. Making them ideal for spectroscopic instruments in the UV. Our stock ranges of UV fused silica windows also have excellent chemical stability, can be used up to 1050°C and are virtually free from fluorescence. Our stock UV fused silica windows are also available UV antireflective coated for 248-400nm increasing throughput performance.
IR fused quartz windows Our stock range of Infrared fused quartz windows are made from Saint Gobain Quartz HS grade. HS grade IR fused quartz is manufactured by the fusion of naturally occurring crystal quartz in an electric vacuum furnace. This process results in a very low water content (OH) of less than 5 parts per million. These IR fused quartz windows have excellent transmission from 260nm thought to 3500nm and low bubble, striae and inclusion content. HS grade fused quartz is available as ingots, core drilled rods for use to manufacture your custom IR fused quartz windows for your specific application.

White float windows: White float windows are cost effective medium performance windows and acceptable in a host of scientific instrument applications. They are cut from large sheets that are relatively flat and parallel and can be supplied in standard thickness down to 1.1mm.  Thinner windows can be supplied to special order.  As no polishing is required white float windows are extremely economical. White float windows transmit efficiently from 320nm to 2600nm and are a good alternative to BK7or equivalent. They are an economical choice of window as the substrate material is available in standard sheet polished material in a range of thicknesses so no polishing is required, unlike BK7 or equivalent that is originates as block material and requires further processing of sawing and polishing adding to cost.

We offer four versions of white float windows, uncoated, AR coated one face, AR coated both faces and ITO coated.
Uncoated white float windows This range of economical white float windows are available as diameters, squares and rectangles. Large stock sheets can be cut down for your custom uncoated white float windows. White float windows are ideal for a range of display, lighting and scientific instrument applications.
White float windows antireflective coated on one face Our 1mm thk white float windows antireflective coated one face with extended broadband AR coating achieving better than 0.5%R,[email protected] Our 3mm thk range are cut from large 1000x1000mm sheets that are extremely economical achieving better than <1%R,[email protected] in the visible (AV8 specification.
White float windows antireflective coated on both faces Our 1mm thk white float windows antireflective coated on both faces is coated with extended broadband AR coating achieving better than 0.5%R,[email protected] Our 3mm thk range are cut from large 1000x1000mm sheets that are extremely economical AR coated large sheets working efficiently in the visible (AV8 specification) achieving <1%R,[email protected]
White float windows ITO coated on one face have an electrically conducting coating used for a host of defence and aerospace applications. We stock ITO coated white float windows as diameter, square and rectangular apertures. Indium Tin Oxide (ITO) coated windows are used for displays, electric heating and EMI shielding applications. These ITO coated windows “Indium Tin Oxide” are vacuum coated to 20ohm. 

Toughened windows: Toughened glass, also known as tempered glass to our U.S. customers, is commonly used in applications where windows are placed under a great amount of physical strain or pressure. Knight Optical offers a range toughened windows in a variety of glass types, most commonly borosilicate or float glass. Our custom range of toughened glass is vastly more resistant to breakage than untoughened counterparts. The toughening effect is achieved by heating the glass beyond its annealing point (560ºC for borofloat, 546ºC for white float glass), then rapidly cooling the surface. This causes the surface to contract, producing compressive stresses. The inner portion of the window is allowed to cool more slowly – this variation in cooling rate between the inside and surface of the glass produces tensile stresses in the inner portion of the window. The balance between tensile and compressive stress gives our custom toughened windows their increased mechanical resistance properties.

Light guides: Knight Optical’s ranges of light guides are available in a variety of materials. Currently we offer BK7 or equivalent, Sapphire and UV Fused Silica light guides, in an assortment of sizes and thicknesses.

Light guides serve as the key element in cosmetic laser, or intense pulsed light (IPL) applications. IPL is commonly used for the removal of unwanted hair, as well as a range of other cosmetic applications. IPL applications make use of a variety of wavebands to target different chromophores. For this reason, our custom light guides are available in a choice of materials to suit your waveband requirement.

BK7 or equivalent light guides offer high internal reflection to minimise the loss of transmitted light. BK7 or equivalent can offer over 90% transmission between 330 and 2000nm, which makes this material an excellent choice for IPL applications used to treat pigmentation, as the peak absorption of the human pigment melanin is 335nm. BK7 or equivalent is also recommended for its high homogeneity and low bubble and inclusion content.

UV fused silica light guides also provide over 90% transmission at 335nm and work efficiently down to 185nm, making them an excellent alternative to BK7 or equivalent for pigmentation treatment. In addition, our custom fused silica light guides offer high thermal conductivity and an increased laser damage threshold, both of which are essential for cosmetic laser applications.

Sapphire light guides are a common alternative to BK7 or equivalent and fused silica. Sapphire is an extremely hard material, which offers increased durability and resistance to damage. Sapphire also provides excellent transmission over the entire visible and SWIR range.

Knight Optical supply high quality stock windows for a range of applications, industries and sectors. Our stock optical windows are individually tested by our highly skilled metrology and QA technicians.

Contact our multilingual technical sales team and discover how Knight Optical’s high quality stock optical windows can improve your product and supply chain experience.

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Our Multi-Lingual Sales Team are here to help with your requirments:

UK +44 (0)1622 859444
UK +44 (0)1622 850614
UK +44 (0)1622 851078
+1 401 583 7846

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