Classification and structural components
Modern industrial laser generators are divided into four groups depending on the aggregation state of the active medium: solid-state, gas, liquid, and semiconductor (injection).
The basic design of any laser setup includes the following elements:
- Active medium. Determines the type of generator. This can be solid materials (synthetic ruby rod, optical quartz doped with neodymium, erbium, or holmium), gases (argon, helium, neon, carbon dioxide), liquids (dyes like rhodamine or fluorescein dissolved in ethanol and coumarin), or semiconductors (silicon, germanium).
- Two mirror resonators. One mirror is completely opaque, while the second is semi-transparent (to release the finished beam).
- Pumping lamp. An external light source, such as a high-power xenon lamp.
- Capacitor and power supply.
Mechanism of radiation generation
The process of coherent light generation is best illustrated by the example of a classical solid-state laser based on a ruby crystal.
- When the xenon pumping lamp is turned on, a powerful light flux excites chromium atoms (the basis of ruby) into an excited energy state.
- Returning to their initial state, these atoms emit quanta of light — photons.
- The released photons collide with other excited chromium atoms, knocking out new portions of light. An avalanche-like chain reaction process begins.
- The light flux is repeatedly reflected from the resonator mirrors at the ends of the rod. The light energy density rapidly increases.
- Upon reaching the limit value, the energy flux punches through the semi-transparent mirror and emerges as a monochromatic coherent beam (the wavelength for the ruby rod is 0.69 µm).
Properties of the laser beam
Optical quantum generator radiation possesses a unique set of physical characteristics that distinguish it from conventional light sources:
- Monochromaticity — light is generated in an extremely narrow, strictly defined band of the optical spectrum.
- Coherence — absolute ordering of the electromagnetic wave in amplitude (height) and frequency (length).
- Polarization — strict orientation of the electric and magnetic field vectors in a plane perpendicular to the light beam.
- Minimum divergence angle — the beam practically does not scatter in space.
Dosimetry and practical application
When assessing the parameters of laser exposure in occupational hygiene, the main indicator is power density flux (PDF) — the volume of light energy per unit area. Standardly, PDF is measured in W/m², and for low-intensity setups, the unit mW/cm² is used.
Energy or continuous wave generation power is measured in watts (W) or milliwatts (mW). In the case of pulsed radiation, the power of an individual pulse (W/pulse or J/pulse), the duration of the pulse itself (in seconds, milliseconds, or microseconds), and their repetition frequency (in hertz and kilohertz) are evaluated.
The ability to concentrate ultra-high energies in microscopic volumes ensures the widespread use of lasers in manufacturing. They are used for high-temperature effects, particularly for melting, ideal welding, and precise cutting of super-hard materials.
Preventive measures
Due to the high biological impact of laser radiation, occupational safety in manufacturing requires strict adherence to preventive measures. The following approaches are applied to personnel:
- Rationalization of work and rest schedules: introduction of at least two additional short breaks during the work shift.
- Physiotherapy prevention: workers are prescribed massage courses, preventive ultraviolet irradiation, therapeutic exercises, thermal water procedures, and mandatory vitaminization.
- Medical supervision: conducting thorough preliminary (upon hiring) and regular periodic medical examinations to monitor health status.
Briefly: answers to topical questions
What preventive measures are used to protect personnel from laser radiation in the workplace?
To protect personnel from laser radiation in the workplace, a set of preventive measures is applied.
- Rational work and rest schedule — introduction of two additional short breaks.
- Physiotherapeutic procedures — massage, ultraviolet irradiation, thermal water procedures, therapeutic exercises, vitaminization.
- Medical examinations of workers — conducting preliminary and periodic medical check-ups.
What personal protective equipment (PPE) is used by workers when servicing laser systems?
When servicing laser systems, workers use specialized personal protective equipment to prevent retinal damage.
- Protective goggles — equipped with special dark light filters that reduce radiation intensity to the eyes to a safe level.
Goggles can be tight-fitting (open or closed with direct and indirect ventilation) and non-tight-fitting (protective lorgnette, visor goggles, or clip-on lenses).
What specific organ of vision injuries are caused by exposure to laser radiation?
Exposure to laser radiation causes various specific injuries to the organ of vision depending on the wavelength.
- Retinal burns and hemorrhages — occur upon exposure to the visible and near-IR spectrum, leading to the formation of a chorioretinal scar, decreased visual acuity, and the development of scotoma (proceeds without pain).
- Conjunctivitis and corneal burns — caused by UV lasers and accompanied by severe pain.
- Corneal opacity — transient foci occur under the action of gas CO2 lasers due to protein denaturation.
- Chronic changes — include photophobia, lacrimation, increased color discrimination thresholds, and increased dark adaptation time.
Class and exam questions
What does the word "laser" mean?
This is an abbreviation for the English term Light Amplification by Stimulated Emission of Radiation.
Why are mirrors needed in a laser design?
Two mirrors form an optical resonator. They force the photon flux to reflect repeatedly inside the active medium, which leads to an avalanche-like buildup and amplification of light energy before it exits outward.
What units is power flux density measured in?
In the dosimetry system, power density flux (PDF) is standardly measured in W/m². For low-intensity equipment, the dimension mW/cm² is permissible.
What else to study on this topic
- Mechanism of the biological action of laser radiation on tissues
- Engineering and technical means of protection against laser radiation
- Classification of lasers by the degree of hazard of the generated radiation
- Specifics of using eye personal protective equipment
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