Laser safety

Researcher's corner

• Laser Permit Application Form (PDF, 384KB)
• Laser User Registration Form (PDF, 684KB)
• Presentation (PDF, 5.4MB)

Specific topics

• Femtosecond Laser Technology Safety Aspects (PDF, 657KB)
• Laser SOP Template (PDF, 91KB)
• Laser Plumes
• LEDs vs Laser Diodes (PDF, 398KB)
• Manual (available in your lab)

uOttawa links

• Centre for Research in Photonics
• Faculty of Science

Standards

• ANSI American National Standards Institute
• CSA Canadian Standards Association
• CDRH Centre for Devices and Radiological Health
• IEC International Electrotechnical Commission

External links

• Quebec Photonic Network
• Agile All-Photonic Networks
• Canadian Photonics Industry Consortium (PhotonsCanada)
• Canadian Centre for Occupational Health and Safety

Regulatory

• Ontario Ministry of Labour
• Radiation Emitting Devices Act
  (R.S.C. 1985, c. R-1)

Free software

• EasyHAZ (Kentek)

Associations

• IEEE Photonics Society
• International Laser Display Association
• Laser Institute of America
• Canadian Radiation Protection Association (CRPA)
• International Radiation Protection Association (IRPA)
• International Commission on Non-Ionizing Radiation Protection (ICNIRP)

Suppliers

• Rockwell Laser Industries
• UVEX
• Kentek Laser Store

The laser safety training consists of two mandatory parts (theoretical course and in-lab training) for individuals working with Class 3B and Class 4 lasers and systems. Please follow the steps below to become an authorized user:

1 - Complete the theoretical course

Users must take an online laser safety course: “Basics of Laser Safety” that covers the basics of lasers, bioeffects of laser radiation, laser hazard evaluation, laser classification, laser eyewear, control measures and non-beam hazards.

To register for this online course Please send an email to [email protected] with the following information included:

• User’s first and last names,
• User’s email address,
• PI’s first and last names, and
• Type of lasers or laser systems the user will be working with.

2 - Take in-lab training

Users must receive the in-lab practical training provided by the Permit Holder or the lab delegate and complete a Laser User Registration Form (PDF, 684KB).

3 - Submit your theoretical course certificate and Laser User Registration Form

Submit your theoretical course certificate and Laser User Registration Form to [email protected].

Individuals working with Class 1 to 3R lasers and systems (e.g., confocal microscopes, embedded systems, etc.) can request the online course “Basics of Laser Safety” as well by sending an email to [email protected]. A training material “Principle of Laser Safety” is also available for review. 

All lasers and laser system do not pose the same degree of risk. For this reason, a classification system was developed to categorize these systems depending on their potential to cause biological damage. Although a variety of classification standards exist, depending upon the area of application (ex. manufacturing vs application), the ANSI standard is a generally accepted standard.

Seven classes are used to delineate the risk of damage associated with exposure to a laser beam, and range from Class 1 (no potential damage) to Class 4 (high degree of potential damage).

The potential injury to the skin or eye can be significant and permanent, so every precaution must be taken to avoid this. These precautions are outline in the Control Measures section of this webpage. It is also important to understand the bioeffects of exposure to the different types of lasers.

Skin Exposure is a combination of primary absorption and secondary absorption associated with internal reflection/backscatter of the beam.

Risk factors associated with skin characteristics

• tissue texture
• tissue density
• skin pigmentation
• phototoxic and photosensitizing chemical in skin
• absorption characteristics
• degree of hydration
• chronic exposure

Biological effects

• thermal - denaturation of proteins, coagulation, vapourization
• ablation -  breaking of molecular bonds
• photodisruption - plasma formation with resulting vapourization and ablation
• acoustic shock - plasma creation with acoustic waves break structural components.
• photochemical – energerized molecules either fluoresce or react chemically
• absorption – when associated with low power lasers biostimulation occurs.

Eye exposure

The risk of eye damage is significant, and hence an understanding of how the location of exposure in the eye will determine the severity of the damage is required.

Summary of basic laser biological effects

Courtesy of: Rockwell Laser Industries – Industrial Laser Safety 1999

Minimal reactive dose levels for skin damage

* at 50% probability levels for minimal tissue reaction, except for excimer which is minimal level for tissue ablation.

Courtesy of: Rockwell Laser Industries – Industrial Laser Safety 1999

Principal Investigators who use lasers are responsible for ensuring that all lasers are appropriately labeled and warning signs are conspicuously displayed in locations where they will best serve to warn on-lookers.

The following requirements must be followed for proper labelling of lasers and posting of signs:

• The signal word "Caution" must be used with all signs and labels associated with class 2 and some 3R lasers or laser systems.
• A class 2 laser or laser system must be labeled with the warning "Avoid Long Term Viewing of Direct Laser Radiation." This label does not need the warning symbol or signal words but must be visible during operation and bear the designation "Class 2 Laser."
• The signal word "Danger" and “the white triangle with the red exclamation mark” must be used with all signs and labels associated with class 3b and 4 lasers and laser systems.
• Appropriate space must be left on all signs and labels to allow inclusion of pertinent information. Such information may be included during the printing of the sign or label or may be handwritten in a legible manner to include the following:

Above the tail of the sunburst, the following special precautionary instructions or protective actions may be required for individuals entering the area:

1. For class 2 - "CAUTION - Laser Radiation - Do Not Stare Into Beam"
2. For class 3R - "DANGER - Laser Radiation - Do Not Stare Into Beam or View Directly With Optical Instruments"
3. For class 3B - "DANGER - Laser Radiation - Avoid Direct Exposure to Beam"
4. For class 4 - "DANGER - Laser Radiation - Avoid Eye or Skin Exposure to Direct or Scattered Radiation"

Above the tail of the sunburst, precautionary instructions or protective actions to be taken by the reader should be provided such as "invisible beam, knock before entering, do not enter when light is on, restricted area, etc."

Below the tail of the sunburst, the type of laser (e.g., Ruby, Helium-Neon, etc.) or emitted wavelength, the pulse duration if appropriate, and the maximum output must be provided.

At the lower right, the class of the laser or laser system must be provided.

The University of Ottawa is using many types of laser systems for a variety of purposes, such as teaching, research, laboratory experiments, etc. It is not uncommon to find different classes of lasers in a single laboratory. Laser hazard evaluations and the application of appropriate controls must rely on the following five aspects:

1. The laser or laser system's capability of injuring personnel
2. The beam path of the laser radiation
3. The environment in which the laser is used
4. The personnel who may use the laser or be exposed to laser radiation
5. The interaction of the beam with its intended target

Lasers are classified into 7 classes (see Laser Classification) according to the level of hazard they create. There are three elements that form the basis of the laser hazard evaluation that each user must be aware of prior of using a laser:

1. MPE - Maximum permissible exposure: the level of radation to which a person may be exposed without expected hazardous effects (W/m2)
2. NHZ - Nominal hazard zone: the space in which the level of direct, reflected or scattered radiation during normal operation exceeds the applicable MPE(m)
3. LCA - Laser controlled area: the area is defined to contain laser radiation. The room or enclosure must shield the public areas to ensure that members of the public may not be inadvertently exposed to laser radiation or non-beam hazards associated with the use of laser.

Non-beam hazards

• fires (electrical or laser produced)
• production of toxic gases, fumes, and aerosols (Laser Generated Air Contaminates (LGAC))
• improper ventilation
• electrical hazards (unprotected wiring)
• spills (water, dye, chemical)
• lack of MSDS for gases and laser/target by-products
• access control (both in terms of room access and to laser beam)
• lack of hazard signage
• interlocks defeated, not functional or present
• no lock-out / tag-out provisions

Operator and third party considerations

• the maturity of judgement of the laser operator(s)
• general level of training
• awareness of onlookers of potential hazards and safety precautions
• degree of laser safety training
• reliability of users to follow standard operator and safety practices
• number of individuals and their location in the room ,(in relation to primary and secondary beam hazards)
• other hazards in the room which may result in an unexpected action of an individual, influencing the laser operation
• the potential access to the laser facility of untrained parties (housekeeping, maintenance and trade personnel, visitors)

Links

• Laser Plumes - Health Care Facilities
• Lasers - Health Care Facilities

A variety of measures are available to reduce the risk of exposure, these controls range from engineering controls to the choice of personal protective equipment. The focus of control centres on either managing the environment, or the personnel. It is important to consider these needs at the outset of designing the system to ensure the appropriate resources and infrastructures are available to support such measures. A general description of each measure will be discussed.

Engineering controls: are features designed into a laser system and facility, which are used to reduce exposure either to the direct or indirect beam. These controls include: protective housings, enclosures, interlocks, beam stops, elimination of reflective surfaces, local exhaust ventilation, and access control.

Administrative controls: include training, both theoretical and practical; employing risk evaluation tools such as safety audits and inspections; inventory analysis; emergency planning; signage; reporting and investigating accidents and incidents (including near misses); and ensuring appropriate authorization for laser access.

Procedural controls: are a primary means of protecting individuals as well as demonstrating due diligence. These controls include standard operating practices (SOP's) for laser operations, maintenance, servicing, or emergency shut downs.

Personal Protective Equipment (PPE): may be required to protect against injuries associated with direct or indirect beam hazards. The characteristics of the laser and its application will determine the selection and necessity of eyewear, skin coverings, and in some cases respirators.

The University of Ottawa follows the requirements stated in the American National Standard for the Safe Use of Lasers (ANSI Z136.1 - 2007), since it has been adopted by the Ontario Ministry of Labour (MOL). To ensure compliance with the laser safety standards, the University has established an internal laser permit process (i.e.: Permit to Use a Laser Emitting Device) through the Radiation Safety Committee in collaboration with the Office of the Chief Risk Officer.

A permit is required for all classes of laser emitting devices on campus. Failure to comply with these requirements could have an impact on the safety of users and other members of the University community in contact with laser devices. The following application must be completed and sent to the Laser Safety Specialist and approved by the Assistant Director, Radiation and Biosafety Manager at the Office of the Chief Risk Officer.

Permit amendments

Part of the laser compliance program is an accurate, up-to-date laser inventory for each laboratory that operates one or more lasers. So have you just purchased a new laser? Did you get a laser from a colleague in another laboratory? Have you disposed of a laser? Have you modified your current laser settings or operating parameters? This form is also used to amend your permit. Please let us know!

When adding or modifying setups, a Laser Hazard Evaluation (LHE) may also be necessary. If you need assistance disposing of a laser, please contact the laser compliance specialist and indicate the disposal using our form.

Laser Emitting Device Form (PDF, 387KB)

Whether you are shutting down a lab completely or simply moving your lab to a new location, you must inform the Laser Compliance Specialist. The ANSI requirements of our program insist that an accurate account of laser devices be kept.

If you are moving labs, co-ordinating the move with the Laser Compliance Specialist will ensure that your new space is ready as soon as you are to continue your research.

Please fill in the Laser Emitting Device Form (PDF, 387KB) to document these changes. Be aware that if you are removing the laser device from the campus that you will need to co-ordinate with other services to deal with any hazardous materials associated with your laser.

In either case, if the laser is stored, in transfer or being disposed, remove the key from the control box and keep it somewhere secure and if possible, remove or disable any power cords. These steps will secure the laser from unauthorized use.

Introduction

The use of laser pointers has become widespread. The pointers are useful tools for educators in the classroom and at conventions and meetings. However, due to the low cost and ubiquitous supply, these pointers are now being purchased and used by the general public, including children, and used in ways not intended by the manufacturers. As a result, serious concerns about the hazards of laser pointers have surfaced.

FDA Laser Pointer Video

Types of laser pointers

The majority of the laser pointers used in the U.S. have either Class 2 lasers with a maximum power output of less than 1 mW or Class 3a diode lasers in the 630-680 nm wavelength (red), with a maximum power output of between 1 and 5 mW.

There have been reports of more powerful laser pointers imported from Russia and China that lack the appropriate warning labels and have laser beam emissions exceeding the maximum permissible exposure recommended by the American National Standards Institute (ANSI Z136). These laser pointers theoretically could cause significant damage to the eye.

All laser pointers should have a small sticker on them with either a yellow "Caution" or black and red "Danger" insignia, the laser classification (2 or 3a), the maximum output power (in milliwatts mW) and the wavelength. It is prudent not to purchase or use unlabeled laser pointers.

Potential hazards

The hazards of laser pointers are limited to the eye. Although with most visible lasers, the largest concern is potential damage to the retina, most laser pointers are not likely to cause permanent retinal damage.

The most likely effects from exposure to viewing the beam from a laser pointer are afterimage, flashblindness and glare. Flashblindness is temporary vision impairment after viewing a bright light. This is similar to looking directly at a flashbulb when having a picture taken. The impairment may last several minutes.

Afterimage is the perception of spots in the field of vision. This can be distracting and annoying, and may last several minutes, although there have been reports of afterimages lasting several days.

Glare is a reduction or complete loss of visibility in the central field of vision while being exposed to the direct or scattered beam. This is similar to viewing oncoming headlights on a dark night. Once the beam is out of the field of vision, the glare ceases. While this does not pose a hazard to the eye, it can cause serious distraction and outrage. Glare can be exacerbated when the beam is reflected from a mirror-like surface.

Laser pointer tips

• Never shine a laser pointer at anyone. Laser pointers are designed to illustrate inanimate objects.
• Do not allow minors to use a pointer unsupervised. Laser pointers are not toys
• Do not point a laser pointer at mirror-like surfaces. A reflected beam can act like a direct beam on the eye.
• Be aware of irresponsible uses of pointers so the psychological effect will be minimized if you are illuminated by one.
• Do not purchase a laser pointer if it does not have a caution or danger sticker on it identifying its class. Report suspicious devices to the FDA.

Links

• Federal Performance Standard for Laser Products, 21 CFR 1040.10, Center for Devices and Radiological Health, Rockville, Maryland
• Laser pointer

What are the effects of laser energy on the eye?

The site of damage depends on the wavelength of the incident or reflected laser beam:

• Laser light in the visible to near infrared spectrum (i.e. 400 - 1400 nm) can cause damage to the retina resulting in scotoma (blind spot in the fovea). This wave band is also know as the "retinal hazard region".
• Laser light in the ultraviolet (290 - 400 nm) or far infrared (1400 - 10,600 nm) spectrum can cause damage to the cornea and/or to the lens.

(See other Biological Effects)

What factors should be considered when selecting specific eyewear?

They are two important factors to consider:

1. Laser wavelength at which protection is afforded.
2. Optical density (OD) of the eyewear for the wavelength being used. OD refers to the ability of a material to reduce laser energy of a specific wavelength to a safe level below the MPE. It is expressed by the following formula:
   • OD = log10(Ei/Et)
   • where Ei= incident beam irradiance (W/cm2) for a "worse case exposure" and Et = transmitted beam irradiance (MPE limit in W/cm2)
   • Example: OD = 4.0 means that 1/10,000 of the laser light energy will be transmitted through the eyewear

How to determine the required optical density (OD)?

1. calculation (you may use a software such as Easy Haz from Kentek)
2. consulting nomograms or tables (e.g., ANSI 136.1 guidelines)
3. consulting the laser manufacturer or
4. contact the Laser Safety Specialist or call 613-562-5800 ext. 2000

The OD of the eyewear will decrease if the eyewear is damaged. The damage threshold refers to the maximum protection that the eyewear will provide for at least 5 - 10 seconds following noticeable melting or flame.

The other factors to consider are:

1. Comfort of the design to enhance compliance.
2. Field of view provided by the design of the eyewear.
3. Absence of irreversible bleaching when the eyewear filter is exposed to high peak irradiance.
4. Effect on color vision: the colored filter material may reduce color vision and contrast, creating additional hazards. For example, certain eyewear may interfere with visualizing monitoring equipment or detecting cyanosis during general anesthesia.
5. Impact resistance. The eyewear must be resistant to dust, heat, etc., so that they will not loose their effectiveness.

Here is a checklist for eyewear selection!

Laser Protective Eyewear SafetyNet Sheet#73 from the Environmental, Health and Safety Department at UC Davis

The unprotected human eye is extremely sensitive to laser radiation and can be permanently damaged from direct or reflected beams. For this Laser safety eyewear (LSE) in the form of goggles, glasses, or shields must be worn at all times during laser operation to prevent ocular injury. LSE come in a variety of types, colours, styles and prices. It is important to use the LSE specifically designed for the characteristic of your laser. Check both the wavelength and OD imprinted on all LSE prior to laser use, especially in multi-wavelength facilities where more than one laser may be located in the same room. The integrity of  LSE must be inspected regularly since small cracks or loose fitting filters may transmit laser light directly to the eye.

Laser safety eyewear are not created equally and the least expensive is not necessarily the best. What price do you put on your eyesight ? Invest in the proper laser safety eyewear!

The three elements needed to carry out a laser hazard evaluation are the same ones to be considered for eye safety:

• Maximum permissible exposure (MPE) is the level of laser radiation to which a person may be exposed without hazardous effects or biological changes in the eye. MPE levels are determined as a function of laser wavelength, exposure time and pulse repetition rate. The MPE is usually expressed either in terms of radiant exposure in J/cm2 or as irradiance in W/cm2 for a given wavelength and exposure duration.

  • Exposure to laser energy above the MPE can result in tissue damage.

  • The ANSI Z136.1 standard defines MPE levels for specific laser wavelengths and exposure durations. Generally, the longer the wavelength, the higher the MPE; the longer the exposure time, the lower the MPE.
• The Nominal Hazard Zone (NHZ) is the physical space in which direct, reflected or scattered laser radiation exceeds the MPE. Laser safety eyewear must be worn within the NHZ. Note: in practical terms, when using dermatologic lasers, the entire laser procedure room should be considered to be within the NHZ because the laser fibre or handpiece can be directed anywhere in the room.
• The Laser Controlled Area (LCA) is designed to contain laser radiation. The room or enclosure must shield public areas to ensure that members of the public may not be inadvertently exposed to laser radiation or non-beam hazards associated with the use of lasers.