Laser Focusing System Guide
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- Felix Glass Co., Limited
- Issue Time
- Oct 11,2026
Summary
This guide explains CO₂ laser focusing systems, focal length selection, spot calculation, troubleshooting and ZnSe optics for laser cutting & engraving.
Laser Focusing System Guide
A laser focusing system converges divergent CO₂ laser beam into a tiny high-energy spot for cutting, engraving and marking. The core component is the ZnSe focusing lens; focal length, lens type and optical alignment directly determine processing quality, spot size and working depth.
Core Working Principle
| Parameter | Rule & Practical Note |
|---|---|
| Focal Length | Shorter focal length = smaller spot, higher energy density, shorter depth of field |
| Longer focal length | Larger spot, lower peak power, deeper depth of field for thick material cutting |
| Standard Material | Laser-grade ZnSe, optimized transmission at 10.6 μm CO₂ wavelength |
| Key Alignment | Beam must be centered on lens; offset will cause oval spot and uneven cutting |
Two Main ZnSe Focus Lens Types
- Plano-convex lens: low cost, widely used for general engraving and thin sheet cutting; flat side faces incoming laser beam
- Meniscus lens: better spherical aberration correction, rounder spot, preferred for high-precision cutting and high-power CO₂ lasers
Focal Length Selection Reference for CO₂ Laser
- 1.5" / 2": Fine engraving, thin acrylic, paper and fabric marking, tiny spot requirement
- 2.5" / 3": Balanced option, most common for mixed engraving and cutting jobs
- 4" / 5": Thick wood, thick acrylic, deep cutting; larger depth of field
Common Problems & Troubleshooting
- Oval cutting trace: laser beam off-center, tilted lens or contaminated surface
- Weak cutting power: lens burn, coating damage, dust or oil contamination
- Fast lens damage: insufficient airflow protection, smoke splash hitting lens surface
- Cleaning rule: optical lens paper + isopropyl alcohol, no regular tissue or cloth
Available Coating Options
- Single-band AR coating @10.6 μm for maximum transmission
- Dual-band AR coating for 10.6 μm + red aiming diode
- High LDT coating for high-power continuous CO₂ laser systems
Machining Capacity & Quality Control
Felix Glass supplies precision ZnSe focusing lenses in plano-convex and meniscus profiles. Strict focal length tolerance, 20/10 scratch-dig surface quality and high uniformity AR coating. Custom diameter, focal length and special coating requests are supported.
Datasheet & Custom Inquiry
Tell us your laser power, required focal length and working material for focusing lens recommendation and quotation.
Request Datasheet & Custom Quote