Overview
IEC TR 63145-202-40:2026 is a technical report published by the International Electrotechnical Commission (IEC) that provides essential information and guidance on frontal stray light in optical see-through (OST) augmented reality (AR) eyewear displays. The standard outlines the technology framework, defines the phenomenon of frontal stray light, categorizes its various types, and discusses optical characteristics relevant to AR device design and evaluation. This report addresses important aspects such as social acceptance and privacy concerns arising from unintended light emissions, helping manufacturers, designers, and evaluators optimize user experience and safety.
Keywords: eyewear display, augmented reality, AR, optical see-through, frontal stray light, IEC standard, OST, stray light evaluation.
Key Topics
Optical See-Through Combiner Technologies
- Half-tone combiners: Utilize semi-transparent coatings to balance reflection and transmission, commonly used in bug-eye and birdbath optics.
- Polarization combiners: Rely on orthogonal polarization to combine real-world and virtual images with minimal luminance loss, ideal for polarized display engines like LCD and LCOS.
- Wavelength-selective combiners: Use diffractive or holographic elements (DOE/HOE) to reflect specific light wavelengths, enabling selective virtual image display.
- Spatial half-tone combiners: Employ spatially separated mirrors to simultaneously render both real and virtual scenes, adjusting brightness ratio by their proportion.
Frontal Stray Light Phenomenon
The document categorizes frontal stray light in AR eyewear into five types:
- Frontal surface reflection: Reflection of ambient light at the device’s outer surface, observed regardless of device activity.
- Direct transmission: Virtual image leak from the display engine, visible externally when the device is on.
- Facial reflection: Reflection of virtual images off the user’s face or eyes.
- Frontal diffraction: Unintended light directed outwards due to symmetrical diffraction in DOE/HOE-based optics.
- Frontal reflection: Mirror-like reflection of virtual images away from the user’s eye-box, typical in birdbath optics.
Methods to Reduce Frontal Stray Light
- Anti-reflection coatings: Minimize surface reflections on both optical and mechanical parts.
- Angle adjustment: Redirect stray light by tilting or wrapping the optics, though this does not reduce the light itself.
- Optical filtering: Use polarization or spectral filters to block unwanted light while maintaining transparency.
Evaluation Considerations
- Recommendations for environmental conditions (e.g., dark room measurements) to ensure consistent evaluation.
- Utilization of light measuring devices (LMD) placed at standardized distances and angles to assess luminance and area of stray light.
- Social acceptance metrics-such as maximum stray light luminance and size-as well as privacy assessment via modulation transfer function (MTF) analysis.
Applications
IEC TR 63145-202-40:2026 is valuable for a range of applications:
- AR device design and manufacturing: Guides designers in minimizing visible stray light, improving user comfort, privacy, and social acceptance.
- Product testing and evaluation: Provides methodologies for reliably measuring and comparing frontal stray light between AR devices.
- Compliance and quality assurance: Supports industry professionals in meeting current international standards and expectations for augmented reality eyewear.
- Privacy-sensitive environments: Offers guidelines to assess and mitigate privacy risks posed by visible virtual images projected towards onlookers or bystanders.
Related Standards
For a holistic approach to eyewear display evaluation, the following IEC standards offer complementary guidance:
- IEC 63145-1-2 - Eyewear display - Part 1-2: Generic - Terminology
- IEC 62977-2-1 - Electronic displays - Part 2-1: Fundamental measurements of optical characteristics
- IEC TR 62977-2-5 - Electronic display devices - Transparent displays optical measurements
- IEC 62715-5-1 - Flexible display devices - Measuring methods of optical performance
By following IEC TR 63145-202-40:2026, stakeholders can effectively evaluate and mitigate frontal stray light in AR eyewear, enhancing both user safety and industry-wide confidence in augmented reality technologies.