How do sports glasses achieve both clear underwater imaging and fog-proofing?
Publish Time: 2026-01-19
Diving masks, as indispensable equipment for underwater activities, have one of their core functions: providing users with a clear and stable underwater view. However, achieving this goal faces two key challenges: first, visual distortion occurs due to the difference in refractive index when light enters water from the air; second, the warm, humid air exhaled by the user easily condenses into fog upon contact with the inner surface of the lens, obstructing vision. Sports glasses achieve both high-definition imaging and effective fog prevention in underwater environments through collaborative innovation in material selection, optical design, and anti-fog technology.1. Optical Clarity: Precise Matching of Materials and Curved Surface DesignSports glasses are typically made of high-transmittance tempered glass or optical-grade polycarbonate. Tempered glass is highly durable, scratch-resistant, and has a light transmittance of over 92%, minimizing light loss; while PC material, although slightly less abrasion-resistant than glass, offers excellent impact resistance and lightweight advantages, making it suitable for high-dynamic scenarios such as freediving or surfing. Regardless of the material, the lenses undergo precision polishing to ensure a smooth, distortion-free surface. More importantly, the curvature design of the lenses directly affects underwater image quality. Since the human eye cannot focus properly underwater, diving masks restore the eye's refractive power by maintaining an air cavity between the eye and the water surface. Flat lenses lead to compression of the peripheral field of vision and barrel distortion; therefore, high-end diving masks often employ a micro-arc or hyperboloid design to expand the horizontal field of vision and reduce optical distortion while ensuring structural strength, making underwater objects appear more realistically proportioned and positioned.2. Anti-fog Mechanism: From Physical Isolation to Chemical InterventionFog is essentially caused by temperature differences leading to the condensation of water vapor into tiny droplets on the cold lens surface, scattering light and forming a white fog. Anti-fogging in diving masks is mainly achieved through three methods:First, physical anti-fogging. Low-volume diving masks reduce the internal cavity, minimizing the space for humid and hot air to linger, thus reducing the probability of fogging. Simultaneously, a good face seal prevents exhaled air from rising to the lens area, reducing water vapor contact at the source.Second, chemical anti-fog coatings. Many newly manufactured sports glasses have a pre-coated hydrophilic anti-fog layer on the inside. This coating spreads condensed water molecules into a uniform, transparent water film, rather than discrete droplets, preventing light scattering. These coatings are mostly silicone-based or polymer-based, but their durability is limited and they are easily damaged by wiping or seawater salt.Finally, there are user-initiated anti-fog measures. The most common is applying anti-fog agents to the lenses, which also works by reducing surface tension to form a water film. Additionally, temporary anti-fog measures using saliva, while unhygienic, are widely used due to their natural surfactant content. Professional divers also rinse their lenses with water before entering the water to balance the temperature difference between the inside and outside, delaying fogging.3. Synergistic Optimization of Dual ObjectivesIt is important to note that anti-fogging and clear imaging are not isolated objectives. For example, an overly rough anti-fog coating may reduce light transmittance; while overly thick lenses, while increasing pressure resistance, may increase chromatic aberration, affecting visual sharpness. Therefore, high-end diving masks require multi-objective optimization during development: selecting high-transmittance substrates, precisely controlling surface tolerances, integrating durable nano-anti-fog coatings, and optimizing internal airflow paths through fluid dynamics simulations to maximize both clarity and anti-fog performance.The reliable vision provided by sports glasses in complex underwater environments is the result of the combined efforts of materials science, optical engineering, and interface chemistry. From a piece of transparent glass to a precision component with anti-fog, pressure-resistant, and wide-angle properties, it embodies a profound understanding of light, water, temperature differences, and ergonomics. In the future, with the development of new technologies such as self-cleaning coatings and intelligent temperature-controlled lenses, the clarity and stability of underwater vision will be further improved, bringing a safer and more immersive underwater experience to diving enthusiasts and professionals.
