Don’t Believe Any Vendor’s Hype: What Exactly Makes a Good Pair of Smart Glasses

Recently, a well-known digital blogger AK in the circle shared his views and opinions on what makes a useful pair of smart glasses. With nearly 30 years of glasses-wearing experience and as a practitioner in the smart glasses industry, his viewpoints focus on the basic principles of optical design for display-type smart glasses and the current industry status, heavily analyzing the internal structure and design challenges of light waveguide technology, using the Meta Ray-Ban Display glasses as an example to reveal the technical bottlenecks and user experience problems prevalent in the industry. Due to the video’s length, the editor has summarized it for everyone. Anyone with different views is welcome to discuss in the comments section.

Core Viewpoints and Background

1. The wearing experience of smart glasses extremely depends on the quality of optical design.
   • Smart glasses with flat frames and lenses easily cause dizziness and missing fields of view.
   • Severe reflection on the inner side of the lenses indicates a lack of anti-AR (reflection) coating, producing ghost images, affecting the field of view experience; not recommended for purchase.
   • Insert-style prescription lens solutions increase weight and compromise optical performance, so they are also not recommended.
   • If front light leakage occurs when the display is on, it indicates deficiencies in the display area’s eyebox and optical path design, resulting in poor long-term usage experience; it is essentially a pseudo-demand.
   • Approximately half of potential smart glasses users do not wear glasses, so when many vendors promote smart glasses based on the premise of “good glasses,” users lack basic judgment capabilities, and vendors’ definitions of “good glasses” vary greatly, leading to ungrounded promotions.

02 Basics of Smart Glasses Optical Design

1. Three-Layer Structure of Light Waveguide Lenses (Taking Meta Ray-Ban Display as an Example)
   • The virtual image is approximately parallel light, giving a visual sensation of infinity; long-term viewing causes eye fatigue.
   • VID1 adjusts the virtual image focal length to a range of 1~2 meters, more in line with human eye habits, through the action of a convex lens, effectively relieving ciliary muscle fatigue.
2. Push-Pull Principle
   • Push-Pull refers to pushing the virtual image farther or closer through the VID1 convex lens to form a reasonable focal length, avoiding eye fatigue caused by staring at an infinite virtual image for a long time.
   • VID2 adjusts with negative diopter to make the glasses overall present a plano state, facilitating normal wearing for non-myopic users.
3. Focusing of Display Virtual Images and Visual Fatigue Issues
   • Virtual images are usually set at about 1 meter, consistent with daily observation distances.
   • Dilemma of binocular display: If the virtual image distance is set relatively close (1~2 meters), users switching sightlines frequently in long-distance environments (tens or even hundreds of meters) will experience accommodation and convergence conflicts, leading to eye fatigue and dizziness.
   • Staring at a close-range display for a long time and frequently switching between near and far vision is the main cause of visual discomfort.

03 Challenges in Prescription Lens Design and Industry Status
Theoretically Optimal Solution

1. Making the user’s prescription lens directly on the VID2 layer can greatly simplify optical design and improve wearing experience.
2. This solution integrates the entire three-layer lens group, ensuring visual effects and comfort.

Three Major Costs of This Solution
Existing Mainstream Solutions and Their Defects

1. Most manufacturers have not adopted the theoretically optimal solution due to manufacturing costs and after-sales difficulties.
2. This leads to common problems for users wearing smart glasses, such as reduced light intake, decreased field of view quality, and increased weight.

Meta Ray-Ban Display Case Analysis

1. Meta is currently the only manufacturer adopting the theoretically optimal solution, i.e., customizing prescription lenses on the VID2 layer.
2. However, it is limited to within 400 degrees, while the video author himself has 700 degrees of myopia and cannot use the official solution, having to use inserts or adhesives as alternatives, leading to optical compromises.
3. Although this glasses model has leading optical design, its domestic ecology is almost empty, affecting promotion and user numbers.
4. The author has “mixed feelings” about this product, acknowledging its superior optical design but experiencing limitations due to degree restrictions and ecological limitations.
5. The optical design of most display-equipped smart glasses on the market is immature, prone to dizziness, light leakage, and wearing discomfort.

Summary of Industry Status and Recommendations

1. Currently, display-type smart glasses are not yet mature, with problems in weight, frame curvature, display area position, FoV (Field of View), reflection, and light leakage.
2. To date, the author still recommends non-display smart glasses as the main choice for daily wearing.
3. The Meta Ray-Ban non-display model (Gen2 Limited Edition) is currently the most mature and wearable smart glasses on the market, supporting prescription lens and photochromic lens customization, with good sales.
4. Optical basic knowledge of display-type smart glasses is key to deeply understanding the industry and technology; the author will continue to share details on coatings, anti-reflection, light leakage, frame curvature, etc., in future videos, combined with reviews of multiple products.

06 Explanation of Key Concepts and Terms
(Note: Specific terms were listed in the original document but not detailed in the provided text snippet, so they are omitted here for brevity unless specific terms need translation.)

07 Summary

1. The key to optical design for display-type smart glasses lies in reasonably adjusting the virtual image focal length, reducing optical loss, and minimizing visual fatigue.
2. Currently, the industry has not universally achieved the theoretically optimal integrated prescription lens solution, constrained by costs and manufacturing complexity.
3. User wearing experience still has many deficiencies, especially regarding dizziness, light leakage, and visual fatigue.
4. Meta Ray-Ban Display is currently a representative of relatively advanced optical design but is limited by degree range and ecological environment.
5. Non-display smart glasses are currently a more mature and practical choice.
6. Future videos will continue to delve into other optical details of smart glasses and analyze the pros and cons of multiple products.

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