Coated viewports for UHV applications.

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Coated viewports for extreme performance

Ceramisis offer a range of competitively priced coated viewports UHV Conflat, ISO or KF including antireflection and ITO coatings

Transmission & Anti-Reflection Coatings

All windows and viewports suffer Fresnel reflectivity losses
Reflectivity r = [(n-1)/(n+1)]2
(where n is the refractive index)

which can be on the order of 6% per face for high refractive index windows such as Sapphire. The reflection is different for p and s polarised waves, and is a function of angle.
This problem can be a severe limitation in many applications requiring optical fidelity, viewing of low luminosity against a high ambient, power transmission etc.

However the problem can be mitigated using anti-reflection coatings. In the case of Sapphire, due to a fortuitous relationship between the refractive indices, a considerable improvement can be obtained using a simple single QWOT (Quarter Wave Optical Thickness) of MgF2.
For more conventional viewport materials such as Kodial and fused quartz this simple approach would provide less obvious, but still useful benefit.

More complex multi-layer dielectric coatings enable a wide variety of tailored transmission / reflection characteristics giving for example virtually zero reflection at a single design wavelength (‘V’ coating) or at two wavelengths (‘W’ coating), or over a wide band BBAR or a neutral density attenuation, and many others.

A 4 layer Broad Band AR Coating – optimised typically but not exclusively for the visible range and giving the best general performance, with a reflected luminosity of only 0.13% and transmitted luminosity of 99.86%

For applications requiring the best transmission at a single wavelength, such as high power laser applications, Ceramisis can provide a ‘V’ Coating having just about zero reflection at a design wavelength 550, 1064 nm etc. for example


Ceramisis can also provide more exotic coated viewports such as MgF2, CaF2, ZnSe, with coatings to provide optimum transmission in the Infrared or UV end of the spectrum
X-Ray Shielding

Lead Glass windows are often used in conjunction with vacuum viewports to reduce the 'leakage' of ionising radiation. However the high lead content gives the glass a high refractive index, and therefore a high reflectivity also.

Again the application of an AR coating can considerably improve the visibility of lead glass windows.
 

Ceramisis Viewport Range

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