How to Select the Right Protective Optical Window


Protective windows are an essential element in any automation system. Although they may not be a fundamental component, they serve an integral purpose in safeguarding critical components. Protective windows are one of the most cost-effective ways to ensure system longevity, repeatability and reliability. With so many material and coating options, here's how to select the best protective window for our system.

Bild: Midwest Optical SystemsBild: Midwest Optical Systems
Image 1 | An oleophobic coating resists moisture, oils, grease and smudging from fingerprints. This can prevent buildup of substances. that could interfere with the clarity of the window.

Material Options

When choosing a protective window, we first need to select the substrate material. For applications where the optics may be prone to scratches or used as a wear plate, a scratch resistant material should be selected. If the window will be exposed to high temperatures, like in a hot steel or glass factory, a material with a higher temperature rating is important. If the system uses a thermal or LWIR sensor, a material that can withstand harsh environments should be chosen. Let's take a closer look at the available materials:

  • • Acrylic: Abrasion-, breakage- and solvent-resistant; durable, economical and laser-able; optical-grade and anti-reflection coated; oleophobic coating available.
  • • Fused Silica/Quartz: Ultra-low thermal expansion; withstands temperatures of up to 1,100°C; superior transmission in the UV; multi-layer anti-reflection coating available.
  • • Borofloat: Impact-, chemical- and alkali-resistant; withstands temperatures of up to 450°C, wavelengths range from UV, visible (VIS) and NIR; durable multi-layer anti-reflection coating; oleophobic coating available.
  • • Precision Windows: Made with precision polished N-BK7; low image distortion and stain-resistant; free of bubbles and inclusions; ideal for low power laser applications; excellent transmission in the VIS and NIR.
  • • Sapphire: Stronger than standard glass windows; durable to withstand harsh environments; impact-, chemical- and alkali-resistant; transmits wavelengths ranging from UV, VIS and SWIR.
  • • Germanium: Diamond-like carbon (DLC) coating; can withstand harsh environments; ideal for thermal camera enclosures; 7.5 to 12.5 micron useful range.

Midwest Optical Systems

Dieser Artikel erschien in inVISION E-Magazin inVISION International (english) 2023 - 18.10.23.
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