Custom Crystal Quartz

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.

Considerations

• 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

Waveplates

• 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.

Monochromators

• 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).