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Sapphire Optical Windows Perform in Demanding Applications


Sapphire Windows manufactured from single crystal sapphire are ideal for demanding applications such as laser systems, where high pressures, high temperatures, high thermal loads, vacuum conditions, scratch/wear resistance, low friction and corrosive atmospheres are important considerations.  As a result, they are often used in research, medical, aerospace and military applications.  Here are some reasons why.

  • Except for diamonds, sapphire is the hardest crystal known to man.  On the Mohs scale of hardness, which ranks materials from softest (1) to hardest (10), it is rated 9.  Because of its structural strength, sapphire optical windows can be made much thinner than other common dielectric optical windows with improved transmittance as a result.
  • Sapphire optical windows have a very wide optical transmission band from UV to near-IR (0.15-5.5µm). Because of their high transmittance from 150 nm to 5 µm, they are much preferred in aerospace applications.
  • Sapphire optical windows are significantly stronger than other optical materials.  Windows manufactured from it are extremely hard and much more durable than standard glass and therefore ideal for military and aerospace applications.
  • Sapphire Optical Windows feature extreme surface hardness and chemical resistance. They are highly resistant to scratching and abrasion, rated 9 on the Mohsscale of hardness from softest (1) to hardest. They are also highlyresistant to all chemicals except some very hot caustics.
  • As sapphire has an extremely high melt temperature (2030°C), optical windows manufactured with it are ideal for thermally demanding environments.
  • Sapphire optical windows are ideal for applications where high pressure, high temperature, high thermal loads, vacuum, scratch/wear resistance, low friction and corrosive atmospheres are a consideration. As a result, sapphire windows and waveplates are often used in research, medical, aerospace and military applications.

 

Sapphire wave plates

Sapphire Wave plates have the same material properties as other sapphire components,including hardness second only to diamonds. They can be made in sizes as thin as 0.4 mm and <25 mm in diameter with transmitted wave front error of less than of λ/10 @632.8 nm.

 

Sapphire wave plates are very similar to sapphire windows and are highly resistant to scratching, chemicals, fluctuating temperatures and shock.  A sapphire wave plate can change the polarization state of a laser beam.  For example, a ¼-wave plate can transfer linear polarization to circular and vice versa.

 

Sapphire wave plates use the birefringence of sapphire to their advantage to make low order wave plates from single crystal sapphire. These thin wave plates extend IR polarization control into the 3 to 5 µm wavelength range while more common quartz wave plates, on the other hand, do not transmit light. Sapphire Wave plates are commonly made out of either A-Plane or M-plane cut sapphire to get the highest birefringence possible, close to 0.008.

 

Because of their outstanding physical, chemical and optical properties, sapphire wave plates are often used in the most demanding military and aerospace applications.