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
Ruby and sapphire are widely used in optical components and micromechanical devices, thanks to their exceptional mechanical, optical, and electrical properties. However, these superior characteristics also pose significant challenges to traditional machining: their ultra-high hardness accelerates tool wear, inherent brittleness demands precise control, and thermal sensitivity makes them prone to material damage. As an advanced process, femtosecond laser technology opens a new door for the high-precision manufacturing of transparent materials like ruby and sapphire.
Ruby discs are commonly applied in watch dials.
Ruby and sapphire both belong to the trigonal crystal system of corundum minerals, with aluminum oxide (Al₂O₃) as their core component. Corundum can exhibit all colors in nature: corundum with a red hue intensity above 5 is called ruby, while corundum of all other colors (white sapphire, yellow sapphire, orange sapphire, pink sapphire, blue sapphire, green sapphire, etc.) is classified as sapphire.
• Ultra-High Hardness & Wear Resistance: With a Mohs hardness of 9 (second only to diamond), their wear resistance far exceeds that of metal materials. For example, ruby nozzles used in 3D printing leverage their single-crystal structure to achieve ultra-high dimensional accuracy—surface finish, roundness, and edge uniformity all meet micron-level standards, and their service life is 5–10 times that of stainless steel nozzles.
• Excellent Optical & Thermal Performance: High transparency and stable refractive index make sapphire the top choice for semiconductor nitride epitaxial substrates and high-end optical lenses. Meanwhile, the high thermal conductivity of ruby and sapphire enables them to withstand high-temperature working conditions, adapting to harsh scenarios in aerospace, semiconductors, and more.
• Strong Environmental Adaptability: Exceptional chemical stability (resistant to acid and alkali corrosion) allows them to maintain long-term performance stability in high-pressure nozzles for food chemistry and edge trimming components in the paper industry.
The machining difficulty of ruby and sapphire directly limits the R&D and mass production of advanced devices. Since they are inert to most wet chemical etching and dry etching processes, laser machining has become the industry-recognized "preferred solution." However, conventional laser machining still faces three major challenges:
• Risk of Thermal Damage: Nanosecond lasers have a long pulse width (10⁻⁹ seconds), so energy continuously conducts into the material interior—causing ruby discoloration and sapphire thermal cracking, which damages the material’s optical and mechanical properties.
• Low Energy Utilization: Sapphire’s high transmittance to visible and infrared light disperses conventional laser energy, making precise focusing difficult and reducing roundness and surface finish.
• Precision Control Difficulty: Machining complex structures leads to large dimensional deviations and low yield rates.
These pain points have made ultra-fast lasers (picosecond, femtosecond) with "cold machining" characteristics the focus of attention. Their ultra-short pulses avoid thermal accumulation, and ultra-high peak power enables precise material removal—providing a new path for the precision machining of ruby and sapphire.
Our femtosecond laser technology, centered on "high-stability femtosecond laser equipment + full-process process control," avoids defects of traditional machining from principle to application, achieving high-quality, stable machining of ruby and sapphire.
The pulse width of femtosecond lasers (on the order of 10⁻¹⁵ seconds) is much shorter than the thermal relaxation time (material heat dissipation time) of ruby/sapphire. Energy does not conduct to the surrounding area; instead, it "instantly vaporizes" aluminum oxide molecules in the machining area. The heat-affected zone (HAZ) is RA < 0.2μm, achieving a cold machining effect without thermal cracking.
Case– 40μm Microhole Machining of Ruby (Industrial Nozzles)
• Aperture: 40μm ± 1μm
• Microhole roundness error: < 1μm
• No discoloration on hole walls, precise taper control, and smooth hole walls.
To address sapphire’s high transparency pain point, we optimize beam absorption efficiency by adjusting laser wavelength and pulse energy density—realizing precise switching from "gentle ablation" to "efficient removal." This enables precise depth-controlled etching of sapphire with femtosecond lasers, avoiding material damage caused by over-machining and achieving complex structure shaping without redeposition or residues.
Case – Sapphire Microstructure Boss Machining (Optical Components)
• 5mm × 5mm square groove depth: 200μm (tolerance ± 1μm)
• No edge chipping on the central boss
• Machining efficiency increased by up to 300% compared to traditional methods.
Central Boss Structure
The equipment integrates a high-precision visual sensing system, laser power monitoring and compensation technology, and 24/7 beam directionality and quality detection. During machining, it real-time monitors hole shape dimensions and surface quality, and adjusts processes to avoid aperture deviations caused by power fluctuations or beam shifts—ensuring consistency in mass production.
Femtosecond Laser Machining Effects of Ruby with Different Apertures
The "cold machining" characteristic of femtosecond lasers is ideal for machining hard and brittle crystals. Whether for gemstones like ruby and sapphire, or complex composite materials like glass fiber epoxy resin substrates, their machining precision surpasses that of traditional processes.
If you have such machining needs or require customized processing solutions, please feel free to contact us for collaboration!
