Concept Explainer Sheet: Laser Physics for LSO Training
Fundamentals of Laser Physics and Technology
Purpose:
This sheet provides simplified explanations of key laser physics concepts, types, interactions, and equipment components. It also links theory to workplace safetyand UK legal compliance.
What is a Laser?
Definition:
A laser is a device that produces Light Amplification by Stimulated Emission of Radiation.
Key Features:
- Monochromatic: Light of a single wavelength.
- Coherent: Light waves in phase and direction.
- Directional: Low beam divergence, highly focused.
- High intensity: Energy concentrated on a small area.
Example:
A CO₂ laser (10,600 nm) in dermatology precisely ablates skin tissue with minimal damage to surrounding areas.
Visual Description:
- Imagine a flashlight: normal light spreads in all directions.
- A laser is like a straight, very narrow beam of sunlight through a microscope lens—highly focused and powerful.
Key Laser Concepts
| Concept | Explanation | Workplace Example |
| Wavelength (nm) | Distance between light wave peaks. Determines penetration and absorption. | Nd:YAG 1064 nm penetrates deeper tissue than 532 nm green laser. |
| Beam Divergence | How much the laser spreads over distance. | Low divergence = sharper, safer focus for surgery. |
| Coherence | Waves are in phase; allows precise targeting. | Hair removal lasers focus energy on follicles without damaging surrounding skin. |
Types of Lasers and Uses
| Laser Type | Wavelength | Use Case | Class |
| CO₂ | 10,600 nm | Skin resurfacing, ablation | 4 |
| Nd:YAG | 1064 nm | Hair removal, coagulation | 4 |
| Diode | 808–980 nm | Aesthetic procedures | 3B |
| Fiber Laser | 1060 nm | Industrial metal cutting | 4 |
| Er:YAG | 2940 nm | Precision tissue ablation | 4 |
Tip:
Medical and aesthetic lasers usually have Class 3B or 4, requiring controlled areas and PPE.
Laser-Tissue / Material Interaction
- Absorption: Laser energy converted to heat (e.g., tissue coagulation).
- Reflection: Risk if laser hits reflective surfaces (use beam stops).
- Scattering: Energy disperses in tissue, reducing precision.
- Transmission: Laser passes through material without effect (transparent glass).
Example:
Nd:YAG laser absorbed by melanin selectively destroys hair follicles without affecting skin.
Continuous-Wave vs. Pulsed Lasers
| Type | Description | Example | Safety Implication |
| Continuous Wave | Constant beam | Surgical CO₂ cutting | Higher thermal spread; strict PPE needed |
| Pulsed | Short bursts | Tattoo removal | PulsedLess thermal damage; timingcritical for tissue safety |
Laser Equipment Components
| Component | Function | Safety Note |
| Active Medium | Produces light | Must match intended wavelength |
| Pump Source | Excites atoms | Only qualified operators should adjust |
| Optical Cavity | Amplifies beam | Ensure mirrors are aligned and interlocked |
| Beam Delivery | Handpiece / fiber | Check for damage; avoid accidental exposure |
| Cooling System | Prevents overheating | Prevents thermal hazards |
| Power Supply | Controls output | Lockable controls recommended |
| Interlocks / Shutters | Safety control | Must be operational to prevent exposure |
Application to Workplace Safety & UK Legislation
- HSWA 1974: Employers must protect staff from laser hazards.
- AOR 2010: Exposure must not exceed Maximum Permissible Exposure (MPE).
- PUWER 1998: Laser equipment must be safe and maintained.
- COSHH 2002: Manage laser-generated fumes/plume.
- BS EN 60825-1/14: Provides classification, hazard zones, and control measures.
Example:
A Class 4 CO₂ laser must operate in a controlled area, with OD-rated goggles, interlocks, and signage, in compliance with AOR 2010 and BS EN 60825-1.
Learner Task
Instructions:
Using this Concept Explainer Sheet:
- Explain in your own words:
o How wavelength, beam divergence, and coherence influence laser safety.
o Differences between continuous-wave and pulsed lasers with practical examples. - Choose one workplace scenario (medical, industrial, or aesthetic) and:
o Identify the laser type and class.
o Describe how it interacts with materials or tissue.
o Suggest safety controls and PPE using UK legislation as reference (HSWA 1974, AOR 2010, PUWER 1998, BS EN 60825-1/14). - Optional Visuals:
o Draw a simple diagram showing beam path, controlled area, and safety equipment.