Laser Physics & Technology Glossary for LSOs

Purpose:

The Glossary-Building Activity helps learners:

• Understand and define essential laser physics and safety terminology.
• Apply terminology to real-world workplace situations.
• Connect terminology to UK legislation and standards for compliance.

Detailed Laser Terminology

Term	Meaning	Workplace Example	UK Legislation / Standard
Laser	Device producing Light Amplification by Stimulated Emission of Radiation; highly directional, monochromatic, and coherent light source	CO₂ laser in dermatology ablating skin tissue precisely	HSWA 1974, AOR 2010
Wavelength (nm)	Distance between consecutive peaks of a light wave; determines absorption and penetration in materials	Nd:YAG 1064 nm penetrates deeper tissue than 532 nm green laser in hair removal	BS EN 60825-1
Beam Divergence	The spread of a laser beam over distance	Fiber laser used in metal cutting has low divergence to maintain focus and avoid stray reflections	AOR 2010
Coherence	The phase relationship between light waves, producing a highly directional and focused beam	Laser tattoo removal selectively targets pigment without affectingsurrounding skin	HSWA 1974
ContinuousWave (CW) Laser	Laser emits a constant beam	CO₂ laser cutting in surgery	PUWER 1998
Pulsed Laser	Laser emits short bursts of energy	Tattoo fading or Q-switched lasers in dermatology	BS EN 60825-14
Controlled Area	Designated zone where laser operation occurs; access is restricted	Class 4 laser room in aesthetic clinic	AOR 2010
Maximum Permissible Exposure (MPE)	Safe exposure limit for eyes and skin	Ensures operators do not exceed exposure during Class 3B procedures	AOR 2010
Nominal Ocular Hazard Distance (NOHD)	Distance from the laser where eye exposure reaches MPE	Defines boundary for CO₂ laser safety zones	BS EN 60825-1
Laser Safety Goggles / PPE	Eye protection designed for a specific wavelength and Optical Density	OD 5+ goggles for Nd:YAG 1064 nm	PPE Regs 1992, AOR 2010
Interlock	Safety device that disables laser when protective doors are open	Fiber laser cutting enclosure	PUWER 1998, BS EN 60825-1
Plume / Fume	Smoke or aerosol generated from lasertissue or material interaction	Nd:YAG surgery plume; requires local exhaust ventilation (LEV)	COSHH 2002
Laser Classification	Categories Class 1–4 indicating hazard levels	Class 4 CO₂ laser in dermatology	BS EN 60825-1
Reflective Surface Hazard	Risk from unintended reflection from mirrors, metals, or glass	Industrial fiber laser cutting	HSWA 1974, AOR 2010
Active Medium	Material that produces stimulated emission	Gas in CO₂ laser, crystal in Nd:YAG	BS EN 60825-14
Optical Density (OD)	Measure of eyewear protection effectiveness against specific wavelength	OD 5+ goggles for 1064 nm laser	PPE Regs 1992
Pump Source	Pump Source Excites atoms to produce stimulated emission	Flashlamp or diode in medical lasers	PUWER 1998
Optical Cavity	Mirrors that amplify and direct laser light	Ensures beam coherence in CO₂ laser	BS EN 60825-14
Beam Delivery System	Handpiece, fiber, or mirror system delivering the beam to the target	Handpiece for diode hair removal laser	PUWER 1998
Cooling System	Prevents laser from overheating	Water-cooled Nd:YAG system	PUWER 1998
Energy Density / Fluence	Amount of laser energy delivered per unit area	Adjusted for tattoo removal or dermatology procedures	AOR 2010, BS EN 60825-1
Pulse Duration	Length of time each pulse lasts	Short pulses for selective photothermolysis	BS EN 60825-14
Chromophore	Substance that absorbs specific laser wavelength	Melanin in hair follicles absorbs Nd:YAG laser	HSWA 1974

Notes for Learners:

• Each term is linked to a real-world workplace example, showing practical application.
• UK legislation references help learners connect terminology to regulatory compliance.
• Understanding these terms ensures LSOs can assess hazards, implement controls, and train staff effectively.
• Some terms overlap across scenarios; mastering them helps in risk assessment and planning controlled areas.

Learner Task

Instructions:

1. Using the detailed glossary above, add at least 10 new terms relevant to laser
   physics, laser safety, and workplace procedures. Include for each:
   o Term
   o Meaning
   o Workplace example
   o Relevant UK legislation or standard
2. Select five terms and write a short paragraph for each explaining:
   o How incorrect understanding or misuse could create a hazard.
   o How UK legislation helps mitigate the risk.
3. Optional: Create a diagram linking critical terms in a laser safety chain, for
   example:
   Laser Classification → Controlled Area → Interlocks → PPE → MPE → NOHD
   → Beam Delivery System.
4. Ensure explanations are clear, concise, and supported by legislation.