How to Select the Best Optical Coatings

Applications across a variety of industries rely on high-quality optical coatings to ensure the safety and performance of their operations. The automotive, biomedical, instrumentation, aerospace, military, and construction sectors are especially dependent on optical coatings.  

While certain applications call for a standard filter or coating, more advanced or demanding applications require a custom optical coating. Benefits of custom coatings include: 

• Enhance optical quality  
• Increase/decrease reflectivity (depending on application) 
• Increase durability 
• Provide better temperature and environmental stability 

To ensure the perfect coating for your application, it’s best to partner with a full-service optical coating expert that offers a diverse range of standard and custom lens coatings from which to select.  

Why Are Optical Coatings So Important? 

The right optical coating can provide several performance advantages, including the reduction of unwanted reflections from surfaces and greater light transmission. Certain optical systems require both functions, where the device reflects wavelengths over a specified range while allowing other wavelengths to pass through unobstructed. Complex dichroic thin-film optical filters can offer high reflection over certain wavelengths, and anti-reflection over others. 

Some common coatings include:  

• Anti-reflective coatings  
• Highly reflective coatings 
• Longpass edge filters and Shortpass edge filters 

• Bandpass coatings for UV, visible and infrared wavelengths 
• Beam splitter coatings for UV, visible and infrared 
• Neutral density filters 
• Protective and enhanced aluminum, silver and gold metal coatings 
• Coatings for polarization and/or phase control  

How Do I Ensure I Get the Right Optical Coating? 

Working with the right coatings/filter supplier is critical when choosing the right optical filter or coating for your application. A technically experienced supplier with a deep background in your application and a broad selection of options will have a comprehensive approach to optical coating selection, supporting you at every stage of the process.  

Here’s what to look for in a supplier when choosing your next optical coating: 

Application Experience 

Suppliers with extensive experience in your industry or application will know what works and what does not, providing you the right coating with greater certainty.  

A supplier with a diverse background will also recognize if you need a standard coating or a custom design. Even if you have an entirely new application, your supplier should be able to draw upon similar past experiences to help guide your decision.  

Specialized Coatings 

Specialized coatings provide performance beyond standard coatings by improving optical performance in particular spectral regions, such as UV or IR.  

An experienced supplier will not only offer specialized coatings but also have a team of skilled engineers who know how to optimize a coating design to an application. When applied properly, specialized coatings can meet the most specific or demanding requirements, offering a custom solution for nearly every wavelength range, with any material you may need, from optical glass and crystalline materials to optical fibers and IR materials. 

Specialized Technology  

To make high-quality optical filters or coatings, specialized manufacturing technology is required. You can tell if your supplier has the right technical capabilities if they use technologies such as: 

• Magnetron Sputtering 
• Ion-Assisted E-Beam Deposition 
• Resistance Evaporation 

Having a supplier with advanced in-house polishing, glass fabrication and lamination capabilities will also help you to achieve the best solution possible.  

• Double-sided polishing 
• Custom coring and grinding 
• Dicing 
• Lamination and engraving 
• Optical assemblies 

Testing and Quality Control  

Proper testing and quality control are necessary if you want to ensure your optical coating achieves the exact requirements of your optical system. Reliable and repeatable testing also ensures coating reliability and regulatory compliance.  

The Andover Advantage: High-Quality Coatings, Industry-Leading Delivery Times, and Reliable Customer Service 

With more than 45 years of optical engineering expertise, Andover Corporation specializes in designing and producing high-quality standard and custom optical coatings and filters. No matter what your optical requirements call for, Andover can help you find the perfect optical coating or filter for your application. We also offer industry-leading short lead times and design cycles for reliable, on-time delivery.  

In addition to our team’s diverse background and longstanding track record of engineering performance in even the most demanding applications, we employ a full-service approach to providing the right coating or filter: 

High-Quality Specialty Coatings  

All Andover filters and coatings are optimized for superior optical performance. We routinely manufacture precision custom coatings in the range of 193nm - 15μm. Our coating types include non-polarizing beamsplitters, multi-band dichroics, dual bandpass filters, ultra-narrow bandpass, multi-band AR coatings and more. Substrates include BK-7, color filter glass, Calcium Fluoride, Zinc Sulfide, Sapphire, fused silica, float glass, Germanium, Silicon, and Zinc Selenide.  

Industry-Leading Technology 

From ion beam assist to advanced hybrid technologies, all Andover chambers are internally custom-built, computer-controlled, and use the latest deposition techniques. We also offer custom polishing and glass fabrication.  

State-of-the-Art Testing  

Here at Andover, we utilize both optical and physical testing. Our environmental chambers allow for performance or survivability testing at temperatures from -192°C to +500°C at variable humidity levels. We can measure over the wavelength spectrum of 193nm to 50μm, inspect for even the most minute surface or internal defect, and characterize wavefront distortions down to 1/20 wave. Our tunable interferometer also allows us to perform transmitted wavefront measurements from 350 - 1100nm. 

Total Quality Control 

With our state-of-the-art equipment and optical expertise, we can ensure that your coating meets expectations. Our commitment to total quality control includes our ISO 9001 and AS9100 certifications, which ensure compliance with mil-aero standards and demonstrate our ongoing commitment to performance at the highest levels. 

Optical Assemblies and Prototyping  

With our in-house precision machine shop and extensive metrology department, we have the ability to fabricate, assemble and test a variety of optical assemblies all inside our facility. Once we know what you need, our experienced team can design and manufacture rings, frames and a wide variety of assemblies for mounting your optical filter.  

With Andover’s extensive experience combined with our full-service capabilities, we can get you the perfect optical coating or filter for even the most rigorous application.