Micro-Nano Processing: Femtosecond Laser vs. Picosecond Laser – How to Choose Tool?
In high-precision fields such as microelectronic manufacturing, medical device R...
MONO | 2025-11
INDUSTRY
As the "soul of eye makeup," cosmetic contact lenses are evolving beyond basic color layers—driven by booming demand for personalization, their patterns now embrace "optical aesthetics." Femtosecond laser technology is the critical force elevating them from "contact lens add-ons" to a "specialized cosmetic category."
Cosmetic contact lens patterns start with precision mold machining: designs are transferred to molds via etching or laser engraving, then printed onto lenses through transfer techniques, followed by curing and strict quality checks to ensure pattern durability and aesthetics.
Two main etching methods exist:
Uses chemical solutions (e.g., hydrofluoric acid, sodium hydroxide) to dissolve material surfaces, leveraging isotropic corrosion (uniform etching in all directions) to form patterns. Advantages include low equipment costs, simple processes, and wafer-level uniform etching. However, its fatal flaw is poor precision: lateral etching blurs pattern edges, with risks of corrosive chemical residue.
Dry etching uses plasma or reactive gases to bombard material surfaces, relying on anisotropic etching (prioritizing vertical etching) for better control over pattern shape and depth. Laser etching—including nanosecond, picosecond, and femtosecond lasers—is a type of dry etching.
Femtosecond lasers (pulse width: 10⁻¹⁵ seconds) stand out as high-end technology. Unlike long-pulse lasers, which cause edge jagging or melting due to heat effects, femtosecond lasers produce sharp, clear patterns. By adjusting pulse energy and parameters, they achieve 5-10 micron-level fine pattern machining effortlessly—ideal for intricate features, deep grooves, and complex structures, amplifying dry etching’s dominance in ultra-high-precision scenarios.
Modern cosmetic contact lens designs now focus on complex structures like "iris 仿生 patterns" and "gradient optical prisms." These require mimicking natural iris details (5-10 micron precision) and regulating light refraction via pattern shapes to achieve effects like "natural enlargement" or "eye focus." Femtosecond laser’s high-precision etching makes it the perfect solution for these needs.
Its power lies in "instant energy burst + non-thermal processing":
1、Ultra-Precision Etching: Focused laser beams generate extreme power density on material surfaces, ionizing and vaporizing molecules instantly for "cold ablation." This creates micron-level patterns with sharp edges, controlled depth, and a heat-affected zone (HAZ) <0.2 microns. Adjusting laser energy density and scanning speed enables precise control over etching depth.
2、Complex Pattern Replication: Paired with high-precision vision systems, femtosecond lasers accurately replicate intricate patterns with consistent quality—enabling one-of-a-kind designs.
3、Broad Material Compatibility: Cosmetic contact lens molds use materials like aluminum and ceramics. For hard, brittle ceramics, traditional machining risks cracks or chipping, but femtosecond lasers’ ultra-short pulses minimize heat diffusion, leaving smooth surfaces (no post-polishing needed) for efficient, high-quality results.
Consumer preferences for contact lens patterns are diverse—from subtle naturals to bold, personalized designs—pushing brands to iterate rapidly.
Traditional workflows (metal mold production → chemical etching → prototyping → optical testing) take 4-6 weeks, with repeated mold adjustments if patterns fail. Femtosecond laser etching, however, completes mold patterning in 1-2 hours. Parameters like pattern density, depth, and direction can be adjusted in real time, accelerating sample validation. This not only sharpens patterns but slashes development cycles drastically.
Conclusion
South Korea and Taiwan established early leads in cosmetic contact lens manufacturing, backed by optical lens expertise and synergy with the beauty industry. Though China entered later, its market has boomed—cosmetic contact lens sales now exceed clear lenses by 4x (CBNData). As demand for personalization and functionality grows, manufacturing techniques are upgrading. Femtosecond laser technology, with its ultra-precision etching, is becoming a cornerstone of China’s cosmetic contact lens production, helping the industry shine globally and meet consumers’ evolving pursuit of beauty.
