This training video emphasizes the critical importance of laser safety, detailing the potential hazards associated with Class 3 and Class 4 lasers and outlining essential precautions to prevent serious injury, particularly to the eyes.
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Welcome to the Coherent Laser Safety Awareness Training video. Before we begin,
please note the copyright laws that govern this
program. If you wish to pause this video, you may do so at any time.
Introduction to Laser Hazards
Hi there! Thank you for enrolling in laser training at Coherent. We are very excited
to have you, as you will be training on either a Class 3 or Class 4 laser
that can cause serious injury, blindness, or loss of life. We would like to inform you of
safety practices to ensure you remain safe during and after our training.
Hazards in the laser lab fall mainly into two categories:
which include fire, particulate, chemical, asphyxiation, biological, mechanical,
and electrical hazards. I am here today to talk to you about those hazards and how to avoid them.
At the end of the video, there will be a short quiz to ensure you understand the
safety protocols that must be exercised around lasers. You must pass with an 80%
or better to attend the laser training session. Sit back, take notes, and good luck on your quiz.
Types of Eye Injuries
With any laser, the greatest safety concern is eye protection because a laser beam can
be many thousands of times brighter than the sun. Laser exposure to the eye, even for only
a fraction of a second, can cause permanent eye damage, including blindness. The three areas of
the eye most susceptible to laser damage are the cornea, the lens, and the retina:
The Cornea: A transparent tissue layer covering the front of the eye. Damage
to the outer surface of the cornea may be uncomfortable and painful but will
usually heal. Deeper layer corneal damage, however, can be permanent.
The Lens: Focuses light to form images on the retina. With age, the lens usually
becomes cloudy and can eventually progress to opacity, a condition known as cataract.
The Retina: The inner lining on the back of the eye that contains photosensitive elements. A
part of the retina that provides central vision is called the macula. The small depression in
the center of the macula is the fovea, which provides high-resolution, detailed vision.
Different wavelengths damage different parts of the eye:
Wavelengths in the mid and far IR, as well as the mid-UV, affect the cornea.
Near-UV wavelengths that fall in the range of 315 to 390 nm will damage the lens.
The most dangerous wavelengths to the eye are those focused onto the retina. This range, called
the ocular region, includes both the visible and near-infrared ranges (400 to 1,400 nm).
The cornea and lens have a focusing capability of 100,000 times, making it
easy to understand why even a low-power beam can produce catastrophic damage to the eye.
One common misconception is that bright light does the most damage to the eye. However, this is not
true. For instance, green light is perceived as the brightest, but faint light with a wavelength
of 800 nm—perceived at only 1-2% of the actual beam—can still cause significant harm. High-power
laser beams of light at higher or lower wavelengths may be invisible altogether,
contributing to misperceptions of output power and causing eye injuries. This is because the
eye’s blinking reflex to bright light only occurs for a narrow range of the spectrum.
For example, notice in this clip that you cannot see the laser beam burning marks
on metal. The light visible is from the heated metal, not the laser beam.
Laser Classifications
Lasers are mainly classified by two factors: wavelength and power. This is because
different wavelengths penetrate the skin and eyes differently, and power determines the intensity.
During this training, you may work with Class 3 or Class 4 lasers.
There are two types of classification systems: the Code of Federal Regulations (CFR) and the
International Electrotechnical Commission (IEC). Lasers can be classified by one or both systems:
CFR Classifications: Use Roman numerals.
IEC Classifications: Use Arabic numerals.
The classifications overlap but differ in some areas. Here are the classifications:
Class 1: No hazard during normal use. Examples include laser printers and compact disc drives.
Class 1M: Safe under normal use unless magnifying optics (e.g., microscopes) are used.
Class 2: Visible lasers (400-700 nm) with up to 1
mW of output power. Momentary viewing is not considered hazardous, as the eye will
blink within 0.25 seconds. Intentional extended viewing, however, is hazardous.
Class 2M: Similar to Class 2 but with large diameter or
divergent beams that are safe unless viewed through optical instruments.
Class 3: Includes subcategories 3A,
3B, and 3R. These lasers can be hazardous under direct exposure:
Class 3A: Visible lasers with 1-5 mW power. Examples include laser pointers.
Class 3B: Hazardous with direct exposure. Diffuse reflections from matte surfaces are not harmful.
Class 3R: Safe if handled carefully, with restricted beam viewing.
Class 4: The highest hazard level. Can cause instantaneous damage from direct
exposure or reflections. Most commonly used in training labs.
Safety Standards and Regulations
Coherent lasers comply with the American National Standards Institute
(ANSI) and the Occupational Safety and Health Administration (OSHA).
Additional compliance includes the Code of Federal Regulations (CFR), IEC, CSA,
TUV, and UL guidelines. Universal symbols for danger, warning, caution, and notice are used:
Danger: Will cause death or injury.
Warning: Could cause death or injury.
Caution: May cause minor or major injury.
Notice: Possible damage to equipment.
Always refer to the safety section of the operator manual for your laser system.
Protective Eyewear
Proper laser safety eyewear is crucial. Your instructor will provide the correctly rated
eyewear. Ensure your eyewear fits well, provides front and side protection, and is free of
scratches. Eyewear must be marked with wavelengths and optical density (OD) values for the specified
wavelengths. Ask your instructor or Laser Safety Officer (LSO) for recommendations if needed.
Safe Work Practices
Basic tips for staying safe in a laser lab:
Keep lasers on stable surfaces with beams parallel to the ground and below eye level.
Avoid chairs, as sitting may bring your eyes into the laser beam plane.
Minimize exposure by limiting time, intensity, and maintaining a safe distance.
Key terms:
Maximum Permissible Exposure (MPE):
The highest safe dose of laser radiation without adverse effects.
Optical Density (OD): Represents attenuation of the laser beam by eyewear or filters.
Nominal Hazard Zone (NHZ): The distance within which exposure exceeds the MPE without protection.
Remove metallic or reflective jewelry to prevent unintended reflections and
injuries. Protect your skin as it can also be damaged by lasers.
Additional Hazards
Electrical: Water near electrical components can cause lethal hazards. Immediately turn off power
in case of leaks.
Fire: Ensure proper enclosures, inspect equipment, and have fire extinguishers available.
Asphyxiation and Chemical Hazards: Use directed ventilation
and appropriate protective measures when working with hazardous materials.
Mechanical Hazards: Be aware of
heavy tools, sharp objects, and high-pressure gases. Wear fully enclosed shoes.
Emergency Procedures
Your trainer or LSO will inform you
of emergency procedures. Follow instructions and know the location of safety equipment.
Interactive Elements
After viewing this video, take the quiz. An 80% passing score
is required for certification, which is valid for one year.
Summary and Review
Remember: Laser beams can injure without being visible.
Always wear proper eye protection.
Be aware of other hazards, including fire, electrical, chemical, and mechanical risks.
For additional information, contact your instructor or the Coherent product support
hotline. Thank you for watching, and we hope you found this video informative.
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