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BS EN ISO 11151 — Lasers and Laser-Related Equipment — Standard Optical Components
Part 1: Components for the UV, visible and near-infrared spectral ranges; Part 2: Components for the infrared spectral range
🔬 BS EN ISO 11151 specifies requirements for standard optical components for lasers and laser-related equipment, an important basis for standardisation and interchangeability of laser optics. The series is split by spectral range: BS EN ISO 11151-1 applies to the UV, visible and near-infrared ranges, and BS EN ISO 11151-2 applies to the infrared range. The Standard sets requirements for the dimensions, surface form, surface quality, material and coatings of standard optical components (lenses, mirrors, windows, beamsplitters), ensuring interchangeability across manufacturers and equipment.
💡 Optical components in a laser system perform focusing, collimation, reflection, beam splitting and polarisation control; their surface form, surface quality and coatings directly affect beam quality and power-handling capability. Standardised component specifications enable system design and component interchangeability.
1. Series Overview and Scope 📌
In the UK this series is the responsibility of Technical Committee CPW/172 (Optics and Photonics), prepared by ISO/TC 172 “Optics and photonics” with CEN/TC 123 “Lasers and photonics”. Both BS EN ISO 11151-1:2015 and BS EN ISO 11151-2:2015 were approved by CEN in 2015 and published as British Standards on 31 July 2015, superseding the withdrawn BS EN ISO 11151-1:2000 and BS EN ISO 11151-2:2000 respectively.
| Part | Subject | ICS | ISO Equivalent | Spectral Range |
|---|---|---|---|---|
| BS EN ISO 11151-1:2015 | UV, visible and near-infrared components | 31.260 | ISO 11151-1:2015 | UV, visible and near-infrared (UV, VIS, NIR) |
| BS EN ISO 11151-2:2015 | Infrared components | 31.260 | ISO 11151-2:2015 | Infrared (IR) |
⚠️ This series specifies requirements for standard (general-purpose) optical components. For custom components with special purpose or performance, refer to the relevant product standard or a mutually agreed technical specification.
2. UV, Visible and Near-Infrared Components (Part 1) 🔧
BS EN ISO 11151-1 specifies requirements for standard optical components for the UV, visible and near-infrared spectral ranges, including overall dimensions, focal length, aperture, surface form accuracy (fringe count), surface quality (scratch/dig), material homogeneity and coatings. The Standard defines the specification system and marking method, facilitating selection and interchangeability.
In the UV-VIS-NIR band, common optical materials include fused silica, optical glass (e.g., BK7) and sapphire; coating materials and processes are chosen for the operating wavelength. The Standard sets requirements for transmittance, reflectance and damage threshold of these materials and coatings in the relevant band, ensuring performance in the laser system.
3. Infrared Components (Part 2) 🔩
BS EN ISO 11151-2 specifies requirements for standard optical components for the infrared spectral range. The optical materials and coatings for the IR band (typically 2.5 μm to 25 μm and beyond) differ from the visible band; common IR materials include germanium (Ge), zinc selenide (ZnSe), silicon (Si), zinc sulphide (ZnS) and calcium fluoride (CaF₂). The Standard specifies the usable wavelength range, transmittance, refractive index and thermal properties of these materials, together with the surface form and surface quality of the components.
Infrared optics are widely used in CO₂ lasers, CO lasers, infrared thermal imagers, infrared imaging and infrared detection systems. Since IR materials are costly and harder to fabricate, standardised specifications are especially important for cost control and interchangeability.
| Comparison | UV/VIS/NIR (Part 1) | Infrared (Part 2) |
|---|---|---|
| Spectral range | UV, visible, near-infrared | Infrared (above 2.5 μm) |
| Typical materials | Fused silica, BK7, sapphire | Ge, ZnSe, Si, ZnS, CaF₂ |
| Typical application | Visible lasers, diode lasers | CO₂/CO lasers, infrared imaging |
| Key measures | Transmittance/reflectance, surface form, damage threshold | Transmittance, refractive index, thermal properties |
4. Component Specifications, Surface Form and Quality 🛠️
The Standard sets systematic requirements for specifications and quality: aperture, focal length, thickness and chamfer should be standardised; surface form accuracy is expressed in fringes, and surface quality as scratch/dig grades (e.g., 40-20, 60-40); materials should meet homogeneity and stress-birefringence requirements; coatings should meet the transmittance, reflectance and damage-threshold requirements at the working wavelength.
- Dimensions and tolerances: aperture, thickness, focal length taken from the standard series.
- Surface form: fringes and local fringe error should meet requirements.
- Surface quality: scratch and dig grades should meet the specification to avoid scatter and damage.
- Coatings: reflectance/transmittance, absorption and laser damage threshold should meet requirements.
5. Engineering Application Practice 🌐
Standard optical components are widely used in laser processing (cutting, welding, marking), laser medicine, lidar, infrared imaging and optical communications. System integrators use standard components to shorten development time and reduce cost; component manufacturers use them to organise production and ensure consistent quality. For high-power lasers, pay particular attention to the laser damage threshold and thermal effects; where necessary choose high-damage-threshold coatings and appropriate cooling.
🚨 Laser optics are among the most damage-prone parts of a laser system: contamination, scratches, coating defects and excessive power density can damage the component and even cause a chain failure. Keep components clean, never touch the optical surface, and match components to the power requirement.
6. Frequently Asked Questions ❓
❓ Q: Why are there two parts by spectral range?
A: The optical materials, coatings and performance requirements for the UV-VIS-NIR and IR bands differ greatly (e.g., material transmittance, refractive index and thermal properties), so they are specified in two separate parts.
A: The optical materials, coatings and performance requirements for the UV-VIS-NIR and IR bands differ greatly (e.g., material transmittance, refractive index and thermal properties), so they are specified in two separate parts.
❓ Q: What does a surface-quality grade such as 40-20 mean?
A: The numbers indicate the scratch and dig grades (e.g., scratch 40, dig 20). Lower numbers mean a cleaner surface with less scatter and less impact on laser damage.
A: The numbers indicate the scratch and dig grades (e.g., scratch 40, dig 20). Lower numbers mean a cleaner surface with less scatter and less impact on laser damage.
❓ Q: Why is the component damage threshold important for high-power lasers?
A: High power density causes the coating and substrate to absorb and heat up; exceeding the damage threshold damages the coating or substrate, seriously degrading beam quality and endangering the system. Choose components with a damage threshold above the actual power density.
A: High power density causes the coating and substrate to absorb and heat up; exceeding the damage threshold damages the coating or substrate, seriously degrading beam quality and endangering the system. Choose components with a damage threshold above the actual power density.
❓ Q: Can standard components meet all laser-system needs?
A: Standard components cover general needs and significantly reduce cost and lead time; but for high-power, special-wavelength or special-spot applications, custom components are still required and should be accepted per a technical specification.
A: Standard components cover general needs and significantly reduce cost and lead time; but for high-power, special-wavelength or special-spot applications, custom components are still required and should be accepted per a technical specification.