Europe, UK, Asia & RoW: [email protected] +44 (0)1622 859444 | USA & Canada: [email protected] +1 401-583-7846

BREXIT UPDATE: Knight Optical will continue to provide quality assured service for all your optical requirements both custom & stock. We will handle all requirements caused by the new regulations.


Looking For a Custom Optical Solution? Enquire

Custom Windows

custom windows, infrared windows, cell windows, optical coated windowsAs well as offering stock windows, ready to order, Knight Optical is experienced in providing fit-for-purpose optical windows manufactured to our customers own requirements. From UV windows designed for use in Excimer lasers to infrared germanium windows used in thermal imaging, Knight Optical has been at the forefront of providing precision, high quality optics to a vast number of different industries.
Below are our typical manufacturing capabilities for visible applications using Schott (or equivalent) material however we are always expanding our capabilities so please do not hesitate to contact us. Due to the different manufacturing/growing processes for more specialist UV and IR substrates the manufacturing capabilities can vary. Our infrared materials page has further information on different substrates available.


Diameter (mm)

Form Error (lambda)

Parallelism (arc mins)



2 to 300+

< 0.25

< 3

< 60/40

Light guides

5 to 100+

< 0.25

< 3

< 60/40


5 to 300+

Concentricity: < 0.05mm

< 60/40

Click on the graphs below to see the typical AR coatings that Knight Optical can provide. 

BBAR 450-900nm

BBAR 1050-1700nm

Browse the categories below for further information on the different windows and diffusers Knight Optical can help with.

Additional Information

  • For a fast turnaround on small orders, it is possible to edge down our stock windows to meet more specific requirements.
  • Knight Optical can also provide windows and diffusers with more bespoke requirements requiring CNC edging or drilled holes.


Knight Optical can also apply a wide range of coatings to your optical windows to enhance their transmission or increase their durability:

  • Antireflective (AR) coatings, including broadband coatings, to optimise the transmission at certain wavelengths or across a range.
  • Diamond-like carbon (DLC) coating to increase the durability of a surface.
  • Hydrophobic coating to repel water from a surface.
  • More specialist coatings such as ITO, anti-fog and oleophobic.

Quality Assurance

  • The flatness and irregularity of our optical windows are tested on our Zygo Verifire XPZ interferometer, where we can also test the transmitted wavefront error of the window.
  • We check the parallelism on our Trioptics PrismMaster which is accurate to 3 arc seconds.
  • Transmission and reflection scans are conducted on our Agilent Cary 7000 Spectrophotomer which can perform spectral scans at multiple angles of incidence and different polarisations.
  • We can also test infrared optical components on our Agilent Cary 660 FTIR spectrometer.
  • All optics are 100% visually inspected before packaging, our staff are trained to ISO 10110 and MIL-0-13830A, and can check down to 10/5 scratch/dig which is especially critical in laser applications.


Our 2021/2022 Catalogue

Inside Knight Optical’s catalogue you’ll find details of the industries we serve as well as the many other services we can offer. It also showcases hundreds of our most popular products, supported by useful technical information, to help you choose the right part for your application.
Click below to view our digital catalogue now.

view our catalogue

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