Chapter 10 Table of Contents. View the entire chapter in a PDF format. Please use the pdf for printing.

Requirements:
General (5.1)

Penetration Permit

Written Approval for Operation (5.1.1)

Written approval from the SLAC laser safety officer (LSO) is required prior to operation of all Class 3b or Class 4 lasers at SLAC.

Classification (5.1.2)

All lasers must be classified in accordance to the hazard classification scheme presented in Section 3 of ANSI Z136.1-2000 (see Section 4, “Definitions”). (See the SLAC Library Community Pages for available standards. ANSI Z136.1-2000 is available in hard copy, QC483:A55:2000.)

Commercial lasers that are purchased with a hazard classification provided by the manufacturer in conformance with the Federal Laser Product Performance Standard (FLPPS) (21CFR1040.10–11) are in accordance with ANSI Z136.1-2000 and fulfill all classification requirements for ANSI Z136.1-2000.

Lasers fabricated for research and without manufacturer's assurance of FLPPS compliance must also be classified prior to operation.

The LSO may classify lasers and laser systems when

• The classification is not provided
• The classification is not in accordance with the FLPPS
• The intended use is different from the use recommended by the manufacturer
• Engineering control measures are added, deleted, or modified

General Requirements and Control Measures (5.1.3)

As with other safety programs at SLAC, engineering controls are the primary controls used for laser safety. If engineering controls are impractical or inadequate, then administrative or other controls will be enforced. Management will provide adequate supervision, personnel training, facilities, equipment, and supplies to control potential laser and laser systems hazards. The control measures appropriate for the classification apply when the laser is in normal operating mode.

Although some classes of lasers and laser systems have their own specific safety requirements and control measures, the following safety precautions apply to all laser use.

Exposure Levels (5.1.3.1)

• Use the minimum laser radiation required for the application to reduce potential exposure
• Avoid eye and skin exposure and direct viewing of the laser beam. Maintain the beam at a level other than the eye level of a person sitting or standing
• Limit exposure levels to as far below the maximum permissible exposure (MPE) values as is practical. Values for the MPE are below known hazardous levels and can be obtained from the LSO or ANSI Z136.1-2000.

Protective Housing (5.1.3.2)

A laser will be contained in its appropriate protective housing to reduce potential exposure. The protective housing will limit the maximum accessible laser radiation to a level that defines the classification and will have classification labels affixed on a conspicuous part of the laser housing.

• Removable protective housing will comply with the following requirements:
• Housing will contain interlocks that are activated when the housing is opened during operation and maintenance
• Interlocks will not be defeated unless the provisions of ANSI Z136.1-2000, Section 4.3.1.1, have been fully implemented
• Viewing windows (if present) will limit the laser radiation to a level below the MPE

• Walk-in protective housings will comply with the following requirements:
• Entries will allow rapid emergency entrance and exit
• Housings will contain interlocks that turn off the laser when personnel enter during normal or emergency access
• Interlocks will preclude automatic re-energizing of the laser after access. Reactivation of the laser will be initiated manually.
• A clearly marked and easily accessible Emergency Off button will be available within the housing for deactivating Class 4 lasers. The button should be of the red mushroom type with signage stating its purpose and which devices it deactivates.
• When continuous laser operation is necessary, the safety control system can momentarily override the room-access interlocks to allow entry and egress. Overrides will not be automatic and will require manual activation. Override systems will be approved by the LSO, who may require additional control measures.

Warning Signs and Labels (5.1.3.3)

All lasers will have labels on the protective housing that specify their classification. In addition, entrances to controlled laser areas will have signs conspicuously displayed. Signs and labels will be in accordance with the ANSI Z535 series (ANSI Z535.1-2002 and ANSI Z535.2-2002). (See the SLAC Library Community Pages for available standards. ANSI Z535.1-2002 is available in hard copy, T55:A461:2002 and ANSI Z535.2-2002 at  T55:A462:2002.)

Required signs differ for each laser hazard classification. More information on warning signs may be obtained from the LSO.

Medical Surveillance (5.1.3.4)

The SLSO will determine which personnel need eye examinations related to laser use and will refer such personnel to the Medical Department. The Medical Department assists laser personnel in obtaining baseline eye examinations and issues them a medical clearance for laser use if the exam results are satisfactory. Such eye examinations establish a baseline against which suspected eye damage can be measured.

Laser medical eye exams (ES&H Course 253ME or equivalent) are required for all SLAC employees and SLAC users before using Class 3b or 4 lasers at SLAC. They are also required following any suspected laser-induced injury. A voluntary 253ME exit exam is offered to SLAC employees upon termination of employment.

253ME exams can be performed by the Medical Department. A one-week notification is requested for scheduling the exams. 253ME exams (or equivalent) comply with ANSI Z136.1-2000, Appendix E2.2 and E4 and include

1. Review of ocular history
2. Visual acuity test
3. Amsler grid test
4. Color vision test

If the results of the above review and tests are normal, no further tests are required. If an abnormality is found, an additional funduscopic exam may be required. For users (non-employees), SLAC requests that home institutions perform the required medical eye exam and send results to the SLAC Medical Department for review.

If an eye injury due to a laser accident is confirmed, the Medical Department will notify the LSO immediately.

Personal Protective Equipment (5.1.3.5)

Eyewear specifically designed for protection against laser radiation from Class 3b and Class 4 lasers and laser systems will be required when engineering and other control measures are inadequate to eliminate potential exposure in excess of the applicable MPE.

Protective eyewear may include goggles, face shields, spectacles, or prescription eyewear using special filter materials or reflective coatings.

The SLSO will determine which protective eyewear personnel will use by considering the following:

• Wavelength(s) of laser output
• Radiant exposure or irradiance levels for which protection (worst case) is required
• Required optical density at the laser wavelength(s) from calculated MPE (See ANSI Z136.1-2000)
• Visible light transmission required to perform tasks while wearing the eyewear
• Damage threshold due to photobleaching, mechanical trauma, shock, or direct exposure to the laser beam

All laser protective eyewear will be

• Clearly labeled with the optical density at the appropriate laser wavelength(s)
• Cleaned periodically, according to the manufacturer's specifications
• Inspected periodically for signs of damage, such as pitting, cracking, light leaks, or discoloration. Eyewear in suspicious condition will be tested to ensure that it is safe for use or discarded

For further details on protective eyewear for laser use, consult the LSO, and ANSI Z136.1-2000, also see related Chapter 19, "Personal Protective Equipment", in this manual.

Requirements and Control Measures for Class 3b and Class 4 Lasers (5.1.4)

Class 3b and Class 4 lasers, which have greater potential to cause injury, require very specific control measures. Engineering controls will be given primary consideration when instituting the safety measure control program.

Engineering Controls (5.1.4.1)

Engineering controls will include

• Interlock systems that are activated when the protective housing is opened during operation and maintenance
• Service access panels that
• Require an appropriate label
• Are interlocked or require a tool for removal

• Key controls. Class 3b lasers should be provided with a master switch but Class 4 lasers must have a master switch that is operated by a key or by a coded access. Authority for the use of the master switch will be specified in the SOP. The master switch will be locked in the Off position when the laser is not intended to be used.
• Interlocks and attenuators, when collective optics for viewing (such as lenses, telescopes, and microscopes but not prescription eyewear) are used while the laser is in operation. These controls will maintain levels of exposure at or below the corresponding MPE.
• Permanently attached beam stops or attenuators for Class 4 lasers. Permanently attached beam stops or attenuators should be provided for Class 3b lasers.
• Laser-activation warning systems (such as audible and visual alarms) for all, including intermittent or single-pulsed, operations when using Class 4 lasers. Warning systems for Class 4 lasers will allow sufficient time for personnel to avoid exposure before the beam is turned on. These warning systems should be used for Class 3b lasers.
• Clearly marked Emergency Off buttons, as well as non-defeatable safety latches, to deactivate Class 4 lasers in an emergency

Other Controls (5.1.4.2)

Beam Path Control

Beam path control will be determined by hazard analyses for areas where beam paths are "totally-open", "limited-open", or where the entire beam path is enclosed. Enclosed beam paths may be classified as Class 1 lasers where no further controls are required. See Section 4.3.6 of ANSI Z136.1-2000 for detailed information.

Laser Controlled Areas

Laser controlled areas containing Class 3b or Class 4 lasers will

• Be posted in accordance with ANSI Z136.1-2000, Section 4.7
• Have access limited to authorized personnel only
• Have standard operating procedures that require disabling the laser when not in use to prevent unauthorized access

In addition, laser controlled areas containing Class 4 lasers will have entry safety controls, as defined in ANSI Z136.1-2000, Section 4.3.10.2.

All personnel who require entry into laser controlled areas containing Class 3b or Class 4 lasers while the laser hazard is on will

• Be authorized to enter the areas
• Be appropriately trained
• Wear the required PPE in Class 3b and Class 4 controlled areas
• Follow all applicable administrative and procedural controls

Acquisition Procedure for Lasers (5.1.4.3)

Managers and supervisors will notify the LSO whenever the decision is made to fabricate, purchase, or otherwise acquire a Class 3b or Class 4 laser. The Purchasing Department will request written approval from the LSO before an order for these lasers is placed. These precautions alert the LSO to the acquisition of a new laser and prompt the LSO to follow up with the necessary safety reviews and procedures leading to an authorization to operate the laser.

Requirements and Control Measures for Laser Pointers (5.1.5)

Laser pointers have become ubiquitous at SLAC and can be personal property or SLAC property. Whether you use your own or one owned by SLAC you are still responsible for its safe use. The following guidelines must be understood and followed:

• Laser pointers must be labeled with either a caution label used for Class 2 hazard and some Class 3a hazard laser pointers, or with a danger label used for some Class 3a laser pointers.
• Those with a caution label are safer to use because the normal blink response of the eye when exposed to bright light is considered sufficient protection. However, they should be used with caution and never stared into.
• Those with a danger label can cause temporary flash-blindness, after images and glare responses. Permanent damage is possible if the beam is stared into.
• Laser pointers must never be pointed at anything but inanimate objects.
• Never point a laser at a person.
• Laser pointers are not toys. Juveniles should not be allowed to use them unless adequately supervised.
• When choosing a laser pointer it is the best practice to pick a Class 2 hazard laser with a caution label.

continue to Requirements, Roles & Responsibilities (5.1.6)