Laser Safety

. [Virtual Presenter] Hi Everyone, thank you for joining me today. Today’s presentation will be on Laser Safety..

[Audio] Over the course of today's presentation, I will be covering many different topics pertaining to lasers and working safely with lasers. Some of the topics that will be presented to you today include: An overview of Understanding Lasers, including the different parts, functionality, and key terms associated with lasers Laser beam exposure The hazards associated with lasers both biological and non-biological in nature Laser classifications A breakdown of each laser class and its associated hazards and controls Applicable Engineering and administrative controls And we'll wrap up the presentation with a quick summary and a Quiz..

[Audio] We'll start things off by reviewing some key terminologies and the functionalities of Lasers. Did you know that the word LASER is actually an acronym? It stands for Light Amplification by Stimulated Emission of Radiation. The acronym itself describes how a laser operates, I'll cover this in more detail later in the presentation. A laser is a device that produces an intense, coherent directional beam of light by stimulating electronic or molecular transitions to lower energy levels. The beam that is generated by this process is powerful and can be used in many different applications. Lasers typically have two modes and can be operated in a continuous wave or pulsed function. Depending on the application you might utilize a Laser as a continuous wave or pulsed function..

[Audio] Now let's break down the different parts of the laser to better understand how lasers operate. A laser is made up of three main parts. 1) the Laser Medium also sometimes called the grain medium, 2) a pumped-in energy source, and 3) 2 mirrors, one of which is partially transmissive. The laser medium contains atoms that are in a basic or ground state. The energy source is then pumped into the laser medium which increases the energy level and triggers the atoms electrons to become "excited". When electrons become excited, they raise and upon their fall back to a basic state they release a photon. When a photon hits another "excited" electron, that electron returns to its basic state releasing another photon. This continuous chain reaction is the process called Stimulated Emission. If you think back to the acronym for LASER, Stimulated Emission is the " SE" from the acronym..

[Audio] As energy is repeatedly pumped into the laser medium the mirrors help reflect and increase the number of photons. Photons then leave the laser medium through the partially transmissive mirror and a directional beam is created and directed onto the material. The beam that is created is capable of engraving, cutting or marking said material..

[Audio] There are many different types of laser mediums, some of the more common laser mediums are solid-state, gas, and dye mediums. The laser medium is often used to describe the type of Laser. The laser medium is the source that generates the photons and optical gain of the laser. The laser medium is also what dictates the wavelength of the laser beam. The wavelength is then used to determine the laser class and associated hazard level.

[Audio] As I previously mentioned lasers can operate in either a continuous or pulsed mode. The application of the laser will likely depict whether you operate your laser in a continuous or pulsed function since each of these functions have different advantages depending on their use and application. A "continuous wave" is also referred to as a " Repetitive Pulsed" mode. This results in the power output of the laser being continuous over time. Whereas a "Pulsed" laser's output is intermittent pulses of light. Another term for the Pulsed function is called " Q-Switched". I'll go into a little more detail regarding each of these functions in the next few slides..

[Audio] The continuous wave mode of a laser will emit a steady beam of light with a constant amplitude and frequency. The continuous wave mode is often used for drilling, cutting, and welding and you commonly see this application being used in the automotive, aerospace, electronics, and semiconductor industries..

[Audio] The pulsed mode function emits light in an on-and-off or pulsed manner. This function utilizes a shutter-like device and does not allow the emission of laser light unless it is opened. Energy builds up and is released by opening the shutter to produce a single intense laser pulse. The pulsed function is often used in the science and medical fields..

[Audio] Exposure to a laser beam can happen directly or indirectly. There are three main types of beam exposures to be aware of. The first is Intrabeam exposure. This means that the eye or skin is exposed directly to all or part of the laser beam. The second type of beam exposure is called Specular reflections. This comes from mirrored surfaces and can be just as harmful as exposure to the direct beam, especially if the mirrored surface is flat. A curved mirror-like surface will widen the beam and as a result, the exposed eye or skin does not absorb the full impact of the beam, however, there is a larger area for possible exposure when a beam reflects off a curved mirror-like surface. The third type of beam exposure is called Diffuse reflection. A diffuse surface is a surface that will reflect the laser beam in many directions. Mirror-like surfaces that are not completely flat, for example, jewelry or metal tools, may cause a diffuse reflection of the beam. These reflections don't carry the full power or energy of the primary beam, but can still be harmful, particularly from high-powered lasers. Whether a surface is a diffuse reflector, or a specular reflector will be dependent upon the wavelength of the beam. For example, a surface that would be a diffuse reflector for a visible laser may be a specular reflector for an infrared laser beam..

[Audio] The American National Standard ( ANSI) for Safe Use of Lasers has identified maximum permissible exposure limits for the eye and skin. These limits are the maximum level of laser radiation a human can be exposed to without experiencing long-term, adverse effects. The maximum permissible exposure is based on the laser's wavelength, the energy of the exposure, and the duration of the exposure..

[Audio] When it comes to optical hazards and exposure limits there are two terms to be aware of. First is the Nominal Ocular Hazard Distance. This is the distance from the equipment source at which the intensity or the energy per surface becomes lower than the Maximum Permissible Exposure on the eye and on the skin. The second term is the Nominal Hazard Zone. This is the zone in which the laser's radiation exceeds the Maximum Permissible Exposure. This zone must be controlled and additional controls such as personal protective equipment are required..

[Audio] Now that we've reviewed the different parts of a laser, how a laser operates, and key terms related to laser exposure limits we can move to discuss the hazards associated with lasers. Laser hazards can be biological or non-biological in nature. Biological hazards occur by either thermal effects, acoustical effects, or a beam exposure due to photochemical effects and can mildly or irreversibly affect one's eyes and skin. Examples of non-biological hazards include: Electrical, fire/ explosion, compressed gasses, and noise hazards as well as exposure to laser dyes and solvents, and Laser generated air contaminants..

[Audio] As I just mentioned Biological hazards occur by either thermal, acoustical, or photochemical effects and depending on the strength of the laser can result in a mild or irreversible effect on one's eyes and or skin. Thermal hazards are a major cause of tissue damage and are caused when temperature and laser energy are absorbed by the tissue. The degree of the effect depends on the amount of tissue exposed as well as wavelength, energy, and time. Acoustical effects occur when the laser beam causes localized vaporization of tissue causing a shockwave and photochemical effects are the result of laser light and negatively impact cell chemistry through the absorption of atoms and molecules, which can cause tissue damage. Photochemical effects result from the laser light and negatively impact cell chemistry thru the absorption of atoms and molecules, which can cause tissue damage..

[Audio] So how can Lasers affect one's eyes? The cornea, retina, and lens of the eye are the most susceptible to damage by irradiation. The damage is dependent on the wavelength and energy absorption characteristics of the ocular tissues..

[Audio] To protect one's eyes against optical hazards laser eye protection or LEP for short may be required. Laser eye protection is specifically designed for class 3B and 4 lasers or laser systems. Laser eye protection is required to be worn within the normal hazard zone that I described earlier in the presentation. Laser eye protection is not required for class 2 or 3R lasers or laser systems unless conditions where intentional long-term direct viewing is required. The eye protection must be able to withstand either direct or diffusely scattered beams depending on the anticipated circumstances of exposure. Some examples of Laser eye protection include: goggles, face shields, and glasses. Special prescription glasses using absorptive filter materials and/or reflective coatings to reduce the potential ocular exposure to or below the applicable maximum permissible exposure are a possibility if needed. If you wear prescription glasses and are required to wear laser eye protection and this might hinder your ability to perform your job, contact Facilities to discuss the possibility of prescription Laser eye protection. The American National Standard for Safe use of Lasers has identified specific laser eye protection criteria and selection factors and should be evaluated whenever the use of laser eye protection is required..

[Audio] All Laser protective eyewear must be clearly labeled with the Optical Density and wavelength for which protection is afforded. You want to be diligent in cleaning and inspecting your eye protection to ensure they are in satisfactory condition. At a minimum, all eyewear should be inspected annually but it is best to inspect your eyewear before and after each use. During the inspection you want to clean your eyewear and inspect it for any pitting, cracking, discoloration, delamination, or lifting of dielectric coatings. Be sure to check the integrity of the frame and see whether there are any light leaks or coating damage, particularly when inspecting goggles, you want to check the ventilation ports, facepiece for deformities, and the head strap for any stretching that might cause an insufficient fit. Any eyewear that is deemed defective should be removed from service and replaced..

[Audio] Ultraviolet radiation is a common skin and eye hazard associated with lasers. UV radiation can be emitted from the laser discharge tubes and pumping tubes. Beam shielding is used as a control measure to minimize exposure to UV radiation. Additionally, PPE can be worn to further protect against UV hazards. Examples of PPE that can be utilized are UV safety goggles and/or face shields, long-sleeved, tightly-woven clothing that covers the body such as lab coats, and gloves..

[Audio] Now that we've talked about optical hazards, let's talk about skin hazards. Both thermal and photochemical effects can lead to skin damage. Some common effects are burns, increased pigmentation, pigment darkening, photosensitive reactions, and skin cancer. These effects are dependent on the laser's wavelength. Your hands, head, and arms are the skin surfaces most likely to be affected and it's important that engineering controls and protective clothing are used to protect exposed skin. If you operate a class 4 laser it is also recommended that you wear flame-retardant clothing..

[Audio] Now we are going to move on and discuss the non biological hazards associated with lasers. The first non biological hazards we're going to talk about are electrical hazards. The electrical hazards associated with working with lasers are: Electrocution, resistive heating, ignition of flammable materials and arc flash. The American National Standard ( ANSI) for Safe Use of Lasers has identified the following as common electrical hazard problem areas: Uncovered and improperly insulated electrical terminals Hidden " power-up" warning lights Lack of appropriate training such as CPR, electrical safety, and lockout tagout Failure to properly discharge and ground capacitors High voltage energy storage capacitors because they could spontaneously partially recharge after discharge unless they are shorted Non earth-grounded or improperly grounded laser equipment Not following OSHA's Lockout Tagout requirements Excessive wires and cables on the floor creating slip, trip, and fall hazards To reduce the risk of these hazards, enclose high voltage sources and terminals, turn off the power before working on power supplies, and follow lockout tagout procedures. Don't create conducive situations by being grounded or wearing metal and ensure you are up to date on all applicable training..

[Audio] Next, let's talk about the risk of fires. The National Fire Protection Agency or NFPA has its own standard specifically for the protection against laser-induced fires. Steps that you can take to reduce the risk of a fire include: Utilizing opaque laser barriers to block the beam from exiting the work area, utilizing flame retardant materials whenever possible, storing flammable and combustible materials in proper containers, and shielding them from the laser beam. Always remove flammable and combustible materials from the area if possible and have a fire extinguisher nearby..

[Audio] Explosions are another risk associated with working with lasers. High-pressure arc lamps, filament lamps, and capacitor banks must be enclosed and be able to withstand an explosion. Additionally, the laser target and elements of the optical assembly must also be enclosed or equivalently protected to prevent injury to operators and observers. An explosive reaction can occur when using chemical lasers or laser gases. The dust buildup in a system's exhaust can also be an ignition source for an explosion. You want to practice good housekeeping and preventative maintenance to keep your area and equipment clean and functioning and never bypass the manufacturer's safeguards..

[Audio] Compressed gas cylinders are another non-biological hazard associated to working with lasers. Some common compressed gasses used in lasers are: chlorine, fluorine, hydrogen chloride, and hydrogen fluoride. You want to make sure you review the safety data sheet for any compressed gas cylinder being used in your application. Ensure you are properly segregating incompatibles and that they are being stored at the appropriate temperature and are secured from tipping over. Additionally, the ANSI standards require any gas cylinders with an HMIS flammability and reactivity rating of 3 or 4 to be contained in an approved/exhausted cabinet with alarms and sensors. Be sure to follow the established procedure for storing and handling cylinders..

[Audio] Laser dyes and solvents. Laser dyes are organic compound solutions that form the lasing medium for dye lasers. These materials can be very toxic and are often carcinogenic. Refer to the chemical safety data sheet for instructions on storage and handling as well as PPE requirements. You should also have documented SOPs in place in the event that one needs to replace the dye or solvents used in your laser..

[Audio] Another hazard to be mindful of is noise levels. Lasers often use high voltage capacitors, when they discharge, they can be loud. Hearing protection is recommended in these circumstances. The last non-biological hazard is Laser generated air contaminates. Class 3 and 4 lasers can generate air contaminants or biohazards in medical applications. The severity of the hazard is variable depending on many factors, i.e. target material, gas, beam irradiance The potential of air contaminants should be evaluated to determine the need for ventilation controls and/or respiratory protection..

[Audio] Before we move on to discuss the classification of lasers, I want to review some key terms that are associated with working with lasers. It's important to understand these terms because they play a role in the classification and control measures that need to be taken to protect against hazards associated with lasers. You will also likely see these terms on warning labels and operation manuals. The first term is " Laser system". The laser system is the piece of equipment that contains the laser and its enclosure. The enclosure around the laser is considered to be an engineering control and should not be removed as its function is to aid in protecting against the laser's hazards. The next term is "embedded laser". The embedded laser is the laser itself that is contained and enclosed within the laser system. The embedded laser has an assigned classification number. This number is higher than the inherent capabilities of the laser system. Because the embedded laser is contained within the laser system and its enclosure the overall classification of the laser system can be reduced to a lower class. For example, A Class 3B or 4 lasers embedded in Class 1 or 2 enclosure can be considered a Class 1 or 2 laser system and will only require operating controls appropriate for Class 1 or 2 lasers providing that the enclosure is not removed. If the laser systems enclosure is opened or removed for any reason the embedded lasers classification stands and precautions to protect against the embedded lasers classification must be followed..

[Audio] The classification of lasers is extremely important in determining the appropriate controls to implement to protect against hazards and ensure the laser system is safe for operation. ANSI Z136. 1- 2014 Safe Use of Lasers determines the classification of lasers by using a classification scheme is used to describe the potential hazard of a laser or laser system. The classification is dependent on the optical emission intensity and the higher the classification number is, means a greater potential hazard. ANSI has identified several different laser and laser system classifications. The Laser class is represented by a number and or a number and capital letter. The following are laser classes: Class 1, Class 1M, Class 2, Class 2M, Class 3R, Class 3B, and Class 4 Over the next few slides, we'll review each laser class, associated hazards, and controls..

[Audio] The first laser classification we will discuss is the Class 1 Laser system. Some examples of class 1 laser systems include, laser printers, CD, and DVD systems. Class 1 laser systems are considered to be incapable of producing damaging radiation levels during operation and are exempt from any control measures. Class 1 laser systems are not considered hazardous for continuous viewing when the beam is completely enclosed. There are no warnings, PPE, or controls required for the Class 1 lasers system..

[Audio] Next, we have the Class 1M laser system. Some examples of Class 1M laser systems are microscopes and telescopes. Class 1M laser systems are considered to be incapable of producing hazardous exposure conditions during normal operation unless the beam is viewed with collecting optics (e.g., telescope) and is exempt from any control measures other than to prevent potentially hazardous optically aided viewing. A Hazard assessment must be conducted prior to optical viewing of a class 1M lasers in order to determine the proper controls..

[Audio] Next, we will cover a class 2 laser system. An example of a class 2 laser system is a supermarket scanner. Class 2 lasers emit in the visible portion of the spectrum ( 400 nm to 700 nm) and the eyes are generally protected by the aversion response or " blinking". Staring at a Class 2 laser for more than .25 seconds may be hazardous to the eyes. Laser eye protection is required for intentional direct viewing of the beam. " CAUTION" signs are to be used for all signs and labels associated with Class 2 lasers, which do not exceed the applicable Maximum Permissible Exposure for irradiance. In addition to Caution signs, class 2 lasers should be labeled with " Laser Radiation - Do Not Stare into Beam".

[Audio] Next, we have the class 2M laser system. A common example of a Class 2M laser is a laser pointer. For class 2M laser systems the eyes are protected from the " blink reflex" and staring at the beam for over 0.25 seconds can be hazardous. Class 2M systems are exempt from any control measures except for conditions of: Intentional direct viewing of the beam and/or potentially hazardous optically aided viewing. Similar to class 2 lasers " CAUTION" signs are to be used for all signs and labels associated with Class 2M lasers, Class 2M lasers are to be labeled with the following precautionary statement " Do Not Stare into Beam or View Directly with Optical Instruments". PPE eyewear should be worn whenever directly viewing the beam or using magnifying optics..

[Audio] Class 3R laser systems are used for different industrial applications and are potentially hazardous under some direct and specular reflection viewing conditions if the eye is appropriately focused and stable. These lasers will not pose either a fire hazard or a diffuse reflection hazard. These laser systems should be labeled with the precautionary statement " Laser radiation – Avoid Direct Eye Exposure to Beam". Class 3R Laser Systems are exempt from control measures or systems of surveillance except for conditions of; direct viewing of the beam or its specular reflection or unattended operation with the beam directed into a location where it can be directly viewed by the general public or other personnel who may be uninformed about its hazards. In the event that direct viewing, specular reflection, or unattended operations where the beam is directed in a manner that can be viewed by other personnel consider the following: Never aim the beam at a person's eye. Ensure the operation warning light is on. Enclose the beam path. Use shields and barriers. Maintain a controlled access area. Maintain correct workstation height for eye level. Eliminate mirror-like surfaces from the laser path..

[Audio] Next, we have the Class 3B lasers. Berkshire Grey maintains an inventory of all Class 3B lasers and the Laser Safety Officer must be notified and approve any purchase of Class 3B lasers prior to them being brought on- site. These laser systems may be hazardous under direct and specular reflection viewing conditions and requires the approval of appropriate control measures by the Laser Safety Officer in order to reduce the risk of hazardous exposure to the eye from direct or a specular reflected beam. A hazard assessment of the laser must be conducted to identify control measures, the laser-controlled area, and applicable warning devices. A sign must be posted stating Warning- Laser Radiation – Do Not Stare into Beam Embedded Class 3B lasers with protective housings that are large enough to allow authorized personnel within the working space must be protected with an area warning system, for example; floormats and IR sensors that would activate upon entry into the protective housing. If entry into the housing occurs the laser system should be interlocked to prevent exposure over the applicable Maximum Permissible Exposure. Additionally, Class 3B laser systems must be provided with a master switch. This switch shall affect beam termination and/or system shutoff and shall be operated by a key or by coded access. Also, any facility internal and or external windows that are located within the Nominal Hazard Zone of a class 3B laser or laser system must be provided with an appropriate absorbing filter, scattering filter, blocking barrier, or screen that reduces transmitted laser radiation to levels below the applicable Maximum Permissible Exposure. Protective eye protection and clothing are required for Class 3B lasers, and these lasers may only be used by authorized personnel..

[Audio] The last laser class we are going to review is a class 4 laser and laser system. Class 4 is the highest level of hazard classification for lasers. Class 4 lasers are used for various industrial processes. Like Class 3B lasers, they must be approved by the Laser Safety Officer prior to being purchased and brought on site. Berkshire Grey maintains an inventory of all class 4 lasers present on site. Class 4 lasers present severe eye and skin hazards from direct, specular, and diffused reflections. They may also produce Laser Generated Air Contaminants and hazardous plasma radiation. Protective eyewear and fire-retardant clothing are required while operating class 4 lasers. A danger sign stating " Laser radiation – Avoid Eye Exposure to Direct or Scattered Radiation; Avoid Skin Exposure to Direct Radiation" must be posted. A hazard assessment of the laser must be conducted to identify the appropriate control measures. Additionally, all of the controls mentioned on the previous slide regarding 3B lasers are also applicable and required to be implemented for Class 4 lasers..

[Audio] Engineering controls are the preferred means of protection if you can not eliminate the hazard or substitute it with something less hazardous. OSHA requires engineering controls as the primary means of protecting workers from laser hazards. The enclosure of the laser equipment or beam path is the preferred method of control since the enclosure will isolate or minimize the hazard. If engineering controls are impractical or inadequate, the Laser Safety Officer will need to review the operation to ensure that an effective combination of personal protective equipment and administrative control measures including training, and the development and posting of safe operating policies and procedures are implemented; in some cases, multiple types of control measures may have to be used. Engineering controls should never be bypassed without the consultation and consent of the laser safety officer..

[Audio] There are many engineering controls for lasers and laser systems. An engineering control that is required for all lasers and laser systems is a "protective housing". The protective housing is a physical barrier that will contain the beam and laser radiation from exiting the laser system so that the Maximum Permissible Exposure (MPE) is not exceeded outside of the system. Protective housings should be clearly identified and enclose as much of the beam path as possible. When the laser is designed to significantly reduce the accessibility of the open beam, a hazard analysis shall be conducted by the LSO; the analysis must define the area where the beam is accessible at levels above the MPE, and control measures must be implemented. The Protective housing should be interlocked so that if operators open it or remove it during the operation of the laser, the system will shut down preventing exposure. The Protective housing may only be removed by trained service personnel that are using other controls and performing maintenance on the laser. And in any event that the protective housing is removed from the sites, LSO shall be notified..

[Audio] Laser systems are typically manufactured with protective interlock systems that automatically switch off the laser when the protective doors are opened, or the housing is removed. Interlocks are required for class 3B and 4 lasers and laser systems. Defeating or bypassing an interlock system is prohibited..

[Audio] Another important engineering control in laser safety is utilizing barriers and enclosures to prevent the beam from spreading outside of the controlled area and exceeding the maximum permissible exposure level. Laser curtains for class 3B and 4 lasers must be made of non-combustible material. When the barrier does not extend completely to the floor or ceiling the LSO shall conduct a hazard analysis to ensure the safety of workers outside the barrier-protected area..

[Audio] Lasers affixed with viewing windows and diffuse display screens must incorporate suitable means such as interlocks, filters, and or attenuators to maintain the laser radiation at the viewing position at or below the applicable MPE. The laser safety officer must evaluate viewing windows and diffuse display screens used to make sure they are suitable to keep exposures at or below the MPE..

[Audio] Class 3B and 4 lasers must be equipped with visual and/or audible warning devices that alert workers upon startup. Class 3B or 4 laser-controlled areas must have area warning devices that are visible prior to entering the controlled area. These devices are any mechanical or electric device that indicated the laser is operating. Examples include lamps, warning flashes, and audible indications that the laser is about to start up..

[Audio] Over the next few slides, we will discuss the administrative controls used in laser safety. Administrative controls are used in conjunction with engineering controls and PPE. Some examples of administrative controls that we will discuss include: Standard Operating Procedures Training Incident investigation Inspections Medical Surveillance Laser-controlled areas.

[Audio] Written Standard Operating Procedures are required for the operation and service of Class 3B and Class 4 lasers or laser systems and must be approved by the LSO. The SOPs must also be kept with the laser equipment for reference by the operators or maintenance personnel. Refer to the site's Laser Safety Procedure regarding the developing alignment procedures..

[Audio] Training is required for all those who operate or service class 3B or 4 lasers or laser systems. Refresher training is conducted annually and should be documented. Inspections are conducted for all Class 3B and Class 4 laser systems on an annual basis. Additional inspections should be completed following any equipment changes or corrective measures. Don't forget to inspect your PPE as previously mentioned at the beginning of the presentation..

[Audio] It is always important to report and investigate incidents and near misses no matter the severity. Incidents and near misses should be reported to your supervisor as soon as it is safe to do so. If a laser exposure has occurred or is suspected a medical evaluation is required for the affected employee. As a follow-up to the incident the laser safety officer, employee involvement, and supervisor will conduct an incident investigation to determine the root cause..

[Audio] Another administrative control is a Medical surveillance program. Employees subject to exposure to Class 3B or Class 4 lasers must conduct a baseline medical exam by a certified ophthalmologist. Medical examinations are required as soon as possible after a suspected injury or adverse effect from a laser exposure occurs. A medical examination is also required when workers are leaving the job or company. The scheduling of exams is coordinated through the Laser Safety Officer..

[Audio] Another administrative control is a Medical surveillance program. Employees subject to exposure to Class 3B or Class 4 lasers must conduct a baseline medical exam by a certified ophthalmologist. Medical examinations are required as soon as possible after a suspected injury or adverse effect from a laser exposure occurs. A medical examination is also required when workers are leaving the job or company. The scheduling of exams is coordinated through the Laser Safety Officer..

[Audio] Laser-controlled areas for class 3B and 4 lasers are tightly regulated and must follow these minimum requirements. Laser-controlled areas shall: Be controlled to permit lasers and laser systems to be operated only by personnel who have been trained in laser safety and in the operation of the laser or laser system Be posted with the appropriate area warning; warning signs should be posted at the entryway(s) and, if deemed necessary by the LSO, within the laser-controlled area Be operated in a manner that the beam path is well defined Require the appropriate eye protection for personnel working in the area Be under the direct supervision of an individual knowledgeable in laser safety Be located so that access to the area is limited and requires approval Have any potentially hazardous beam terminated in a beam stop of an appropriate material Have only diffusely reflecting materials in or near the beam path, where feasible Have the laser secured such that the exposed beam path is above or below eye level of a person in any standing or seated position.

[Audio] Class 4 laser-controlled areas require safety controls for the entryway to the area. Class 4 laser-controlled areas must incorporate one of the following entryway controls Non-Defeatable Area or Entryway Safety Controls to deactivate the laser or reduce the output at or below the MPE in the event of unexpected entry into the laser-controlled area Defeatable Area or Entryway Safety Controls can be used if it is clearly evident that there is no laser radiation hazard at the point of entry to allow access to authorized personnel that have been adequately trained and have the proper PPE Procedural Area or Entryway Safety Controls where safety latches and interlocks are not feasible (during service procedures) All Authorized personnel shall be adequately trained and have the appropriate PPE upon entry Barrier screens/ curtains shall be used to block, screen, or attenuate the laser radiation at the entryway to prevent radiation levels on the exterior of the barriers from reaching above the MPE.

[Audio] All work areas that have Class 3B or 4 Lasers must have laser warning signs posted clearly in the immediate vicinity. Laser area warning signs will rapidly convey a visual hazard-alerting message that: Warns of the presence of a laser hazard in the area Indicates specific policy in effect relative to laser controls Indicates the severity of the hazard (i.e., class of laser, NHZ extent) Instructs appropriate action(s) to take to avoid the hazard (i.e., eyewear requirements).

[Audio] Laser warning signs shall use the following warning statements from ANSI Z136. 1: " DANGER" to indicate an imminent hazardous situation which, if not avoided, will result in death or a serious injury. This signal word is to only be used for Class 4 lasers with the most extremely hazardous conditions. " WARNING" to indicate an imminently hazardous situation that, if not avoided, could result in death or serious injury. This signal word is to be used with lasers and laser systems that exceed the applicable MPE for irradiance, including all Class 3B and in most cases Class 4 lasers and laser systems. " CAUTION" to indicate a potentially hazardous situation which, if not avoided, may result in minor or moderate injury. It may also be used to alert against unsafe practices. "CAUTION" is to be used for all signs and labels associated with Class 2 and Class 2M lasers, which do not exceed the applicable MPE for irradiance. " NOTICE" to indicate a statement of facility policy that relates directly or indirectly to the safety of personnel or the protection of property. This signal word shall not be associated directly with a hazard or hazardous situation and must not be used in place of "DANGER" or "CAUTION". "NOTICE" is used on signs posted outside of the temporary laser-controlled area, for example, during periods of service.