1. Define the Surface Function

Start by identifying what the surface must do: transmit light, reflect a beam, soften a visible reflection, improve cleaning or survive environmental exposure. AR, HR, AG and AF describe different functions and should not be selected from appearance alone.

This guide converts those functions into practical specifications for optical windows, lenses, domes, mirrors and display covers. The goal is to select and qualify a complete surface system, including the substrate and any later printing, bonding or assembly steps.

2. Coating and Surface-Treatment Selection Table

3. Specify the Substrate and Operating Conditions

Provide the substrate grade, dimensions, thickness, clear aperture and treated faces before finalizing a coating. Layer design depends on the optical properties of the material beneath it. Process temperature, stress and adhesion also constrain the manufacturing route.

Define wavelengths, incidence angles, polarization and the medium touching each face. A flat witness sample may not represent every point on a curved dome. Include the range of local incidence angles and the functional aperture for curved components.

If the surface will be bonded or immersed, identify that condition explicitly. A design optimized for air is not automatically suitable for adhesive or water.

4. Select the Appropriate AR Design

Anti-reflection coatings reduce surface reflection through an engineered optical structure, commonly a thin-film layer stack. Select the design bandwidth to match the source and detector, including wavelength tolerances.

A low reflection value at one wavelength does not establish broadband performance. Specify finished-component transmission separately when absorption and scatter must also be controlled.

5. Select HR or Metallic Reflection

A high-reflection coating redirects useful light. Dielectric stacks can be designed for demanding reflection targets in selected bands; metallic mirrors can serve broad spectral needs depending on the metal and protective layers. Neither approach is universally superior.

For each mirror, specify wavelength, angle and polarization, along with acceptable absorption, scatter and reflected wavefront error. For lasers, include beam size, pulse duration, repetition rate or continuous power, and the required test conditions. A damage threshold from a different laser regime may not be transferable.

Protective or enhancing layers on metal mirrors can improve handling and change spectral performance. Compare the completed coating stack, not the bare-metal name.

6. Understand Anti-Glare Surface Processing

AG treatment modifies the surface texture to redistribute reflected light. It may be created by etching the glass or by an applied textured layer. “Anti-glare” therefore does not always mean a deposited optical film.

The benefit is a softer reflected image, but the tradeoff can include reduced clarity, raised black-level appearance and sparkle on displays. AGC’s display-glass guidance identifies these competing effects. Evaluate candidate finishes on the actual screen at realistic viewing distance and ambient illumination.

Do not specify only “matte.” Agree on gloss measurement geometry, haze method, clarity requirements and an approved appearance sample. Texture uniformity across the panel is also important.

7. AR vs. AG: Choose by the Optical Task

AR and AG can be combined, but the finished combination needs qualification. A coating measured on polished glass cannot simply be assumed to perform identically over an etched texture.

8. Add AF Where Handling and Cleaning Matter

AF or oleophobic treatments change the interaction between contaminants and a surface. Their value is often easier cleaning or modified fingerprint appearance. They do not guarantee that a surface will remain free of marks.

Specify representative contamination, cleaning method and acceptable appearance after cleaning. Water contact angle can be one measurement, but it does not by itself establish oil resistance or fingerprint removability. Include performance after wear, repeated cleaning and chemical exposure.

Commercial combinations such as SCHOTT’s AR plus anti-fingerprint cover glass show that functions can be integrated, but the exact stack and durability remain product-specific.

9. Treat Protection and Strengthening Separately

A protective coating, chemical strengthening and thermal tempering are different treatments. A hard surface film does not create the same residual-stress profile as a strengthened glass substrate. Conversely, strengthening does not automatically improve coating scratch resistance.

Define the actual exposure: wiping, abrasive particles, cleaning chemicals, humidity or other environmental conditions. Require optical and cosmetic limits after the exposure, together with an adhesion criterion where appropriate.

For IR components, a DLC-based stack may be considered when compatible with the substrate and band. Its optical response must be qualified; the word “DLC” is not a universal transparency or durability specification.

10. Plan Face Assignments and Process Compatibility

Mark S1 and S2 on the drawing and describe their installed orientation. Identify coating exclusions, bonding zones, printed regions, electrical contacts and edge treatment. Mixed-function components need a clear boundary between optical apertures and cosmetic or contact areas.

A display cover might use AG+AF on the touched face and black printing on the rear. A protected IR window may use different coating systems on its external and internal faces. These are possible configurations, not universal layer recipes.

Agree on the process sequence with the manufacturer. Strengthening, etching, coating, printing and curing can affect one another; qualifying individual operations does not qualify every possible sequence.

11. Choose a Manufacturing Route by Requirements

Evaporation, ion-assisted deposition and sputtering are manufacturing routes, while AR and HR are optical functions. More than one route may achieve a given requirement. Process selection should account for layer materials, uniformity, stress, substrate temperature, geometry, throughput and inspection.

Ask the supplier to explain how the proposed route meets the acceptance criteria. Do not substitute a prestigious process name or a larger layer count for measurable performance. Where a process is mandatory, document the reason and any change-control requirements.

12. Validate the Finished Component

Use representative prototypes for application validation. Approve the combined optical, mechanical and cosmetic result before releasing production. Keep an approved reference where visual judgment forms part of acceptance.

13. Build a Clear Coating RFQ

A useful RFQ describes function, conditions and verification rather than only listing coating abbreviations. Use the following structure and replace every bracket with a project requirement.

For display projects, also provide the screen type, pixel density, optical bonding arrangement and appearance sample when relevant. For mirrors or lasers, add the operating beam parameters and reflected-wavefront requirements.

14. Frequently Asked Questions

15. Discuss Your Coating and Surface Requirements

Send your drawing, operating wavelengths, application environment, prototype quantity and expected production volume to Felix Glass. Identify mandatory requirements and targets that can be adjusted so the material, coating and manufacturing route can be reviewed together.

Dongguan Felix Glass Co., Ltd.
Email: james@felixglass.com