University Resources, Operations and Policies

Laser Safety Protocol


Policy Statement

Adelphi University strongly believes that every care possible should be taken to prevent accidents and hazards to the safety of all its personnel that include the students, the faculty, and the staff. With this goal in mind, Adelphi University Safety Committee prepared this report for safe handling of lasers. It is mandatory that all the students, the faculty, and the staff follow the procedures detailed in this report while handling the lasers.


Reason for Policy

Lasers are important tools in Medicine, Physics, Chemistry, Biology, Geology, Engineering and a variety of industrial applications. If Laser Safety precautions are not implemented, lasers can cause burns, blindness and electrocution to operators, visitors and cleaning personnel. Individual operators of all lasers must be trained so that they fully understand the safety practices outlined in this manual.


Who Is Governed by this Policy

Faculty, Staff and Students


Policy

Laser Safety Protocols

The following protocols are established to ensure the safe use of lasers and laser systems. The procedures and safety features detailed in this report must be followed by all faculty, staff and students.

The Adelphi University Safety Committee and its subcommittee Laser Radiation Safety Committee are responsible to implement the safety program. The Adelphi University Safety Committee and the Laser Radiation Safety Committee will register the lasers in the different departments of the university, and the workers that use and or operate the lasers. Particular emphasis is for the safety of the students, staff and faculty that use the lasers. The committee will undertake surprise and planned laser safety inspections to ensure that proper safety aspects are followed by the university personnel and the students. The committee will recommend and if necessary post proper required laser warning signs. Additionally when required the Committee will recommend and implement the interlocking mechanisms at the appropriate entrance doors when high power lasers are operated.

The Adelphi Safety Committee will designate a “Laser Safety Officer” (LSO) who is responsible for monitoring laser use and safety. The LSO may conduct planned or unannounced inspections. The LSO may or may not be a member of the safety committee. Heads of the respective laboratories are responsible for the personal protective equipment. They are also responsible for implementing the safety rules of all laser users in the laboratory. This includes all the technical staff, students and faculty.

Laser Beam Hazards

The laser produces a beam of high intensity electromagnetic radiation, highly directed with little beam divergence. When the beam falls on a surface, it produces localized heating, raising the local temperature. The temperatures can cause burning, damage, deformation, discoloration of the surface. Some of these procedures are beneficially employed in laser surgery. But uncontrolled exposures can cause considerable damage to the surface. Laser exposure can be hazardous to the skin and the eye in particular. One should be particularly careful about the retinal hazards. A parallel beam of light (laser beam may be considered as approximately parallel) entering the eye is concentrated by the cornea and the eye lens by a factor of about 100,000 times. Even if one uses a low power laser such as a HE-Ne laser of 1 milliWatt/mm2 (one milliWatt is one thousandth of one Watt) will result in 100 W/mm2 on the retina which can possibly result in a small damaged spot on the retina. However, if the beam is not parallel or diverging or diffusely scattered, the damage is significantly less.

Non-Beam Related Laser Hazards

High Voltage and High Power Supplies
Most of the ion lasers and the solid state lasers employ high voltage and high power electrical sources. High current power sources are extremely dangerous. Persons operating these lasers should be extremely cautious and they should wear full leather shoes as a precaution to prevent electrocution to the Earth. Normally most of the commercial laser power supplies have interlocking mechanisms so that the power supply shuts off if they are open and the high voltage terminals are not covered. One should be extremely cautious while handling the laser power supplies when they are open or if the power supply is locally made or when a commercial power supply is altered for certain applications.

Chemical Hazards
Chemical liquid hazards are not a major problem in the laser laboratories. We do not use dye lasers any more and our tunable lasers are solid state based. However we do have the dye laser for the nitrogen laser which uses a cuvette that encloses a small amount (10 cc) of the fluid. The chemicals will be disposed off as a chemical wastes and not into the sink.

Gas Cylinders
All the gas cylinders have to be rigidly anchored by means of a chain or a belt to a wall or to the cart or to some rigid and stable support. Under no circumstances they can be operated without properly anchoring them. If the cylinder is filled with a gas at high pressure as they normally are, if the neck is broken they can go as a small rocket resulting in major damage to the personnel and the equipment. The nitrogen laser uses nitrogen gas and the waste gas is not a serious problem. However, when trace gases, such as nitrogen dioxide is used, they should be exhausted to the outside, even though only traces of the gas (parts per million level) are often used.

Laser Classification

Lasers and laser systems are classified based on their capability of injuring personnel. All of the lasers at Adelphi University were purchased after 1980. Lasers manufactured after August 1, 1976 are classified by the manufacturer. We can safely use the manufacturer’s classification for safety purposes. As of now, Adelphi University does not have any laser fabrication program. If the situation changes at a later date, the safety classification will be done by the safety committee in consultation with the faculty member involved in the fabrication.

There are five laser hazard classes:

  • Class I lasers and laser systems cannot emit accessible levels of radiation that are capable of causing eye injury under any normal operating condition such as the lasers employed in copying machines, scanners, and printers. A more hazardous laser may be embedded in a Class I product that is not accessible during normal operating conditions, but may be during service and maintenance.
  • Class II lasers and laser systems are visible lasers with have an accessible output ≤ 1 mW. Class II lasers and laser systems are incapable of causing eye injury unless intentionally viewed directly for an extended period. The normal aversion response to bright light (blinking) protects the eye from a momentary exposure.
  • Class IIIa lasers and laser systems have an accessible output between 1-5 mW and do not pose a serious eye hazard unless viewed through optical instruments. Typical laser pointers are of this power range. Eye hazard if the beam is focused into the eye employing an external lens.
  • Class IIIb lasers and laser systems have an accessible output between 5-500 mW for continuous wave lasers and < 0.125 J with a 0.25 second pulse width for a pulsed laser. Class IIIb lasers and laser systems pose a serious eye hazard from viewing the direct beam or reflected (specular) beams. The laser beams are used for research.
  • Class IV lasers and laser systems have an accessible output > 500 mW for a continuous wave laser and > 0.125 J with a 0.25 second pulse width for a pulsed laser. Class IV lasers and laser systems pose a serious eye hazard from viewing the direct beam, specular reflections and diffuse reflections. Class IV lasers and laser systems also pose skin and fire hazards. The laser beams are used for research and industrial applications.

Laser Hazards

The site of damage and threshold at which damage occurs depends on the wavelength, whether it is a small or extended source, the exposure duration, whether it is continuous wave or pulsed, and, if pulsed, the pulse length and pulse repetition frequency. Operating lasers under reduced external light conditions increases the optical hazards because of pupil dilation. The Maximum Permissible Exposure (MPE) is the level of laser radiation that a person may be exposed to without experiencing adverse health effects.

A. Eye Hazards

Bio-effects of the eye are summarized in the following table:

Spectrum Location Effect
UV-C (200-280 nm) Cornea Photokeratitis
UV-B (280-315 nm) Cornea Photokeratitis
UV-A (315-400 nm) Lens Cataract
Visible (400-780 nm) Retina Retinal injury*
IR-A (780-1400 nm) Retina, Lens Retinal burn, cataract
IR-B (1400-3000 nm) Cornea, Lens Corneal burn, cataract
IR-C (3000-1000000 nm) Cornea Corneal burn
* Retinal injury can be thermal, acoustic or photochemical

A. Skin Hazards

Bio-effects of the skin are summarized in the following table:

Spectrum Location
UV-C (200-280 nm) Erythema, cancer, accelerated aging
UV-B (280-315 nm) Erythema, increased pigmentation, cancer, accelerated aging
UV-A (315-400 nm) Erythema, increased pigmentation, skin burn
Visible (400-780 nm) Photosensitive reactions, skin burn
IR-A (780-1400 nm) Skin burn
IR-B (1400-3000 nm) Skin burn
IR-C (3000-1000000 nm) Skin burn

Inventory of Lasers in the Physics Department, Adelphi University

Laser Type Quantity Model Wavelength Power Class
QCL Mid-infra red Invisible radiation Daylight Solutions 1 TLS-CW-MHF 6.08 – 6.16 mm 8 – 25 mW IIIb
Ar Ion Laser Spectra Physics Visible radiation 1 2017-06S 451.9-514.5 nm 6 W IV
Ti:Sa Laser Spectra Physics Visible radiation 1 3900S 750 – 950 nm 750 mW IV
Nitrogen Laser Laser Photonics Visible, Pulsed 1 LN1000 IIIb
Dye Laser Laser Photonics Visible, Pulsed 1 LN107 IIIb
HeNe Laser
JDS Uniphase
1 05-LGR-193 543.5 nm 5 mW IIIa
HeNe Laser
JDS Uniphase
1 Uniphase 105-1 633 nm 5 mW IIIb
He-Ne Laser 1 NT54-154 633 nm 7 mW IIIb
He-Ne Laser Metrologic 1 NT61-338 633 nm 0.8 mW IIIb

G. N. Rao’s Laboratory, Blodgett Hall, Rm. 012

Laser Type Quantity Model Wavelength Power Class
Diode Laser JDS Uniphase 2 DL6148-030 638 nm 40 mW IIIb
Diode Laser Toshiba 2 HL6714G 660 – 680 nm 10 mW IIIb
Diode Laser Toshiba 1 DL5038-021 630 – 645 nm 30 mW IIIb
Diode Laser Toshiba 2 DL5147-042 650 – 665 nm 35 mW IIIb
Diode Laser Toshiba 2 ML101J8 655 – 665 nm 45 mW IIIb
Diode Laser Toshiba 3 FLD6A2TK 675 – 695 nm 35 mW IIIb
Diode Laser Toshiba 2 LT030MDO 750 nm 5 mW IIIb
Diode Laser Toshiba 1 LT027MDO 777 nm 7 mW IIIb
Diode Laser Toshiba 1 LT027MDO 780 nm 10 mW IIIb
Diode Laser Toshiba 1 LT015MDO 830 nm 30 mW IIIb
Diode Laser Toshiba 1 SDL5401-H1 779 nm 30 mW IIIb

Instructional Laboratories, Blodgett Hall, Rm. 003

Laser Type Quantity Model Wavelength Power Class
He-Ne Laser 4 Metrologic 633 nm 1 mW II
Diode Laser 1 Pasco OS8525A 650 nm 1 mW II

Atom Trap Laboratory, Blodgett Hall, Rm. 014

Laser Type Quantity Model Wavelength Power Class
Diode – EC Sacher, Lynx 2 Lynx 780 nm 150 mW IIIb
He-Ne Laser 1 Metrologic 633 nm 1 mW II

Sean Bentley’s Laboratory, Blodgett Hall, Rm. 014

Laser Type Quantity Model Wavelength Power Class
Nd:YAG EKSPLA NL301G/SH/ 1 355 nm No direct access to 1064 & 332 output ~ 50 mJ/pulse; IV
OPO 1 Tunable 420 – 2300 nm Energy of pulse: 1 – 18 mJ (based on λ) IV
Violet Laser 1 405 nm, CW 20 mW IIIb
Fiber Coupled Lasers 2 780 nm, CW 2.5 mW IIIb
Helium-Neon Laser Thor Labs 1 633 nm 5 mW, CW IIIb

Laser Safety Procedures

A. Eye Protection

Laser protective eye glasses are specific to the type of laser used. The laboratory heads should procure the safety glasses that are needed for the different lasers they have in their laboratories. They should have them in adequate quantities for all the workers as well as possible visiting and temporary workers. The Adelphi University Safety Committee can help them in procuring the necessary laser safety eyewear. Additionally, the following guidelines in handling the laser beams are suggested:

  • If possible confine the laser beam to a small area and if applicable use the beam stoppers and beam dumpers to block the beam. This would minimize accidental exposure of the people handling the lasers and the visitors.
  • For alignment purposes, use the lowest power possible. Whenever possible use the low power He-Ne lasers (< 1 mW power) for alignment purposes.
  • Avoid metallic strap watches and metallic jewelry as far as possible while handling the lasers.

Adequate number of laser safety eyewear should be made available at the entrance to the room or at a place where a visitor and a worker can pick up the ware and proceed to the experimental area. It should be made clear that different eye ware is needed for different lasers that may be operating at a given time.

B. Control of Laser Areas

  • Where Class III and higher lasers are in operation, there should be a warning with a red lamp at the entrance to the room with the sign ‘laser in operation’.
  • If several lasers are in operation in a room or several groups share the room, each of the laser area should separated with thick black curtains or curtains that would effectively block the radiation of the particular laser.
  • Locks and the warning signs should be activated when the laser is in operation.
  • Appropriate instructions are given to the cleaning, maintenance personnel and other physical plant people that they should never try to enter the laser room when the laser warning signs are ‘on’ without the clearance from the laboratory head.

C. Laser Transportation

When lasers are moved from one room to another for experiments/demonstrations, the head of the lab would make sure that proper laser safety protocols are observed. If any laser of Class IV is moved from one room to another, the details should be informed to the Laser Safety Officer (LSO). In general it is a good laboratory practice that at least two students work at any given time so that in case there is an emergency, help is available immediately.

D. Instructional Laboratories

Special care should be taken by the instructors if the (freshman) students are allowed to handle the lasers for the experiments. The instructors should inform all the students in the beginning that “The students will never look directly into laser beam” because it is hazardous. This may be repeated a couple of times and make the students repeat the statement so that they clearly understand the laser safety protocols.

E. Maintenance and Physical Plant Staff

Often laser based experiments are conducted and data acquired automatically by computers. It is necessary that the staff follow the following guidelines.

  • Never enter any laser laboratory without explicit authorization from the head of the laboratory or the chair of the department. If some say electrical other maintenance is needed make sure that proper clearances are obtained before entering the laser laboratory.
  • Most of the optics components are very fragile and most of the components should never be touched because when you touch the fingers leave an oil trace that would damage the optical surface. Often you cannot even clean the surface without elaborate procedures. They are quite expensive, a simple glass piece say 1 square cm size can cost several thousand $ depending on the specifications and quality of the surface.
  • Optical tables are high precision instruments and should never be used to keep any items other than the optical components. Never, never step on them under any circumstances.

Emergencies

In case of emergency or if any one feels that he/she may be exposed to laser hazard, please contact, Adelphi University Health Services located in Waldo Hall, phone: 516.877.6000 and Adelphi Security at 516.877.3511.


Definitions

Laser: a device that produces an intense, coherent, directional beam of light. LASER is an acronym for Light Amplification by Stimulated Emission of Radiation. Even though ‘radiation’ is often referred to the nuclear radiation such as alpha, beta and gamma rays, this report addresses to the electromagnetic radiation only and not to the nuclear radiation. Laser beams are monochromatic, extremely directional, have small angular divergence of the beam, and are coherent. Even though the laser beam is electromagnetic radiation, they can cause severe harm to the tissue because they can focus a large amount of energy on a small area resulting in damage to the cells and often causing severe burns. Lasers can be continuous wave (CW) or pulsed and can operate in different regions of the electromagnetic spectrum. The tissue damage depends on the power, energy per pulse, and the region of the electromagnetic spectrum in which they operate. They are often categorized as far infrared lasers (1400 nm – 1 mm), near infrared lasers (780 – 1400 nm), visible lasers (380 – 760 nm) and ultraviolet lasers (200 nm – 380 nm). One should be very careful in handling ultraviolet and infrared lasers because we cannot see the beam and the invisible laser radiation can cause severe damage to the eye and the skin. Specifically, the laser beam can cause damage to the cornea and the eye lens as well as the small region of the retina on which the beam may be focused.


Forms

This policy does not have forms associated with it at this time. Upon periodic policy review this area will be evaluated to determine if additional information is needed to supplement the policy.


Related Information

This policy does not have related information at this time. Upon periodic policy review this area will be evaluated to determine if additional information is needed to supplement the policy.


Contacts

Sean Bentley
p – 516.877.4878
e – bentley@adelphi.edu

Michelle Glover-Brown
p – 516.877.3242
e – mglover-brown@adelphi.edu


Document History

  • Last Reviewed Date: October, 2017
  • Last Revised Date: October, 2017
  • Policy Origination Date: Not known

Who Approved This Policy

Adelphi University Safety Committee

 
 
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