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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.


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Custom Crystal Quartz

Crystalline Quartz (SiO2) is a naturally-occurring birefringent material. It has many optical properties which make it an ideal substrate for a multitude of applications:

  • Birefringent
  • High purity
  • Insoluble in water
  • High damage threshold
  • Rotates plane polarised light

Knight Optical supplies high quality crystal quartz optical components, including windows, prisms, waveplates, and beamsplitters, made to your custom specification. We can offer uncoated and coated optics, including broadband antireflective (BBAR) coatings. Our typical manufacturing specifications are listed below however we are always expanding our capabilities so if your requirements are not mentioned below, please contact our technical sales team who will guide you through your enquiry.


< 5mm to 80mm +

Form error (@633nm)

< 0.25 waves

Centration /parallelism

< 1 arc minute


< 20/10

Typical coatings

BBAR @ 1-2.5µm

DLC @ 1-2.5µm

With our in-house state-of-the-art metrology laboratory you can be confident that your optical components will meet your requirements. You can find out more about our testing facilities here.

Uncoated, 1mm thick

Additional Information

  • Birefringence is when there are two distinct refractive indices of a material. This occurs when an unpolarised light beam enters the input surface of the material, it will be split into two polarised beams—the ordinary (o) and extraordinary (e) waves. Quartz’s o-and e-ray refractive indices are 1.54221 and 1.55333 respectively (@600nm).
  • Crystalline quartz transmits at 90% between 0.18-3.5µm so can be used for UV to NIR applications.
  • It also transmits above 50µm, which goes into the Terahertz region (3mm down to 30µm) which is used for blackbody emission.
  • Crystal quartz is split into left-handed and right-handed types based on the optical rotation of the linearly polarised which enters it.
  • Due to its low thermal expansion, it is a good substrate for precision mirrors.


  • Crystal quartz should be used at temperatures below 490°C.
  • There is some confusion between quartz and fused silica. Quartz is made from naturally occurring crystalline quartz which is melted and purified. Fused silica on other hand is entirely synthetic with enhanced performance in the UV region.

Typical Applications

  • Crystalline quartz is used extensively as low and zero order waveplates due to its birefringence and low absorption.
  • Achromatic waveplates can be manufactured from a crystal quartz and magnesium fluoride which gives a near constant retardation across a wide wavelength range.
  • Quartz waveplates are suited for applications with laser or IR light sources as they have a high damage threshold and stable retardation with temperature fluctuations.
  • Crystal quartz is used as x-ray monochromator plates, like lithium fluoride, due its particular crystalline structure. Its lattice gaps allow for Bragg Diffraction to occur and the formation of intense radiation peaks (Bragg peaks).


Our 2022/2023 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