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Laser Disposal
Introduction
Laser technology is continuously advancing and in some settings, such as universities and research institutions, lasers become outdated or applications change such that particular lasers are no longer needed. Typically, these lasers go to storage, but space is very valuable and a time comes when these laser systems go to salvage. The question arises; can they just be thrown out in routine trash? If one is unaware of the individual components of lasers, the answer seems a simple yes; while, in fact, a number of laser components require careful consideration when it comes to disposal. Hazards and components vary by laser. As an example, the majority of lasers manufactured before July 1, 2006 that use electricity as their source of energy contain lead. In this case, if disposed of improperly, lead may seep into the environment. However, high power gas laser plasma tubes may contain carcinogens. This chapter aims at giving the reader some suggestions and options. The topic has been partially addressed in Z136.1 and Z136.8, in a number of presentations on the Laser Safety Officer (LSO) Workshop series and a laser disposal guide developed by the laser safety program at Lawrence Berkeley National Laboratory (while I was LSO there).
At this time, two groups have a responsibility to see that the laser systems are handled in the proper manner; the user (present owner) and the institution’s property management/salvage department.
Distribution Of Responsibility
Questions for User
Have you contacted Property Management to ask which forms need to be filled out?
If you are disposing of a dye or excimer laser, have you flushed out the chemicals in the pump containers, tubing, and inner cavity? For instructions, please see the Dye Lasers or Excimer Lasers sections.
Do you have the user manual for the laser? If so, send it for disposal with the laser.
Did you contact the LSO to see if he can find a new home for your laser?
Remember to remove the laser from your inventory record.
User Responsibilities
When a laser is getting ready to be released for surplus, the user should find the laser system user manual and send it along with the laser. Although commercial lasers should have several labels on them, the most important for surplus are the manufacturer label and the logo label. From the manufacturer label, one obtains the model and serial numbers. The logo label contains wavelength and output data and might indicate the general laser name (i.e., argon, HeNe). Before sending the laser to surplus, the user shall place a sign on the laser indicating its optical laser medium (i.e., Nd:YAG, dye, argon). This will be a great help to the property disposal group especially if the user manual cannot be found.
Questions for Hazardous Waste Generator Assistant (If Such a Position Exists at Your Institution)
If it is a dye or excimer laser, ensure the user has flushed out the chemicals in the pump containers, tubing, and inner cavity, and disposed of correctly or saved for you.
Majority of power supplies built before 2000 with capacitors will contain capacitor oil; see that the oil is drained and placed in the proper container.
Any other type of laser has no special precautions required for transportation.
Questions for Surplus Receiver
Have you received the proper paperwork?
Is the laser type identified, so the proper disposal steps can be taken?
General Approaches To Laser Disposal
There are several alternatives to laser disposal that may be considered. Some laser manufactures have a cradle-to-grave service and will accept old lasers for recycling value as a service to the user. Surplus personnel are advised to contact the laser manufacture and ask if the laser system may be returned for disposal, refurbishment, usable components, or possible equivalent to new repair. However, not all manufacturers have this option and some require the user to pay for shipping.
It is also possible to transfer the laser to donate it to a local university’s engineering or physics department. It is necessary to ensure that the laser system complies with all applicable safety instructions for operation and maintenance and that the receiving department has a viable laser safety program. A Limit of Liability document will also need to be generated. If it is a Class 3B or 4 laser or laser system that will be transferred, the LSO will need to be contacted. He or she may contact the designated institution to see if they have an LSO and the steps that will be taken to use the laser in a safe manner.
If it is determined that those two options are not viable, the laser will be disposed. The following is an excerpt on general laser disposal:
Lasers, which are to be surplus by the institution, are not to go to public auction. This is due to concerns over the misuse of the laser system; one example is lasers being used to expose commercial aircraft pilots while in flight. The laser must be rendered unusable.
Knowing the manufacturer and model number, a call to the manufacturer is prudent to check on any possible hazardous material components.
Power Supplies
Simple action is to cut off the plug and as much as possible of the AC source cord.
Lasers that use electricity as their main source of energy and manufactured before July 1, 2006 have lead in the printed circuit boards. Dispose of them as electronic waste (e-waste).
Many laser systems utilize a high voltage capacitor system hence an electrical shock hazard is a real possibility. Standard capacitor safety needs to be followed; for example, use of ground hooks, and so on.
Optics
For optics, remove the optics and place them in a ziplock bag. Label bag with laser manufacturer information and then send it to the LSO.
Various lasers require different actions, the following are examples.
Dye Lasers
Active Concern
These lasers use a liquid medium. This medium comprises organic dyes and solvents, all of which must be considered carcinogenic or mutagenic.
Disposal
Wear personal protective equipment. This includes goggles, particle masks, chemical-resistant apron, and gloves. Rinse pump containers, tubing, and inner cavity several times with methanol and then with water until internal circulating fluid appears to be clear. All washing must be considered hazardous waste and dealt with as such.
Once done, cut power cord, remove optics. Place the optics in a ziplock bag, label it, and send it to the LSO.
Common Dyes and Solvents
Coumarin
Rhodamine
Exalite
Stilbene
Oxazine
Dimethyl sulfoxide
Excimer Lasers
Active Concerns
Excimer lasers use a combination of halogen and noble gas. Each has its own risks depending on the quantity and concentration. It also includes an internal electrical system that is required to make the two family of gases form a dimer.
Common Excimer Lasers
Argon fluoride
Hydrogen fluoride
Krypton fluoride
Xenon fluoride
Disposal
User should have flushed out the resonator before sending to surplus as well as any premix chambers. Wear gloves and safety glasses. Remove chamber and crack open in a well-vented area. Remove any circuit boards and dispose of as e-waste. Remove power cord.
Hazardous Materials to Consider
Argon
Fluoride
Krypton
Xenon
Diode/Semiconductor Lasers
Active Concerns
From a size perspective 95% of these laser units are made up of heat sink, current controls, and so on. The actual laser diode is smaller than a paper clip. Some diode laser systems may be part of a diode fiber system.
Common Diode Lasers
Gallium aluminum arsenide
Gallium arsenide
Indium gallium aluminum phosphide laser
Disposal
For individual diode units or arrays, simply break the housing unit taking care to wear protective eyewear. Only if multiple units are received at one time should they be sent to the Hazardous Waste Group (if such a system is present within your institution). They will be treated as e-waste. For fiber optic systems, while wearing safety glasses and protective eyewear, the fiber should be cut near the diode end and fiber segment be put in a sharps container.
Hazardous Materials to Consider
Gallium arsenide (hazardous waste)
Diode/Telecommunications Laser Systems
Active Concerns
In a majority of cases, these lasers contain optical fibers, which are used to deliver laser radiation. A majority of injuries come from handling the fibers. Treat them as potentially sharp components.
Common Telecommunication Lasers
Gallium aluminum arsenide
Gallium arsenide
Indium gallium aluminum phosphide laser
Ytterbium-doped fiber
Disposal
Fibers are to be treated as sharp optical components and need to go into sharp, disposable container. Safety glasses and gloves are to be worn when handling (cut or removes from diode on laser box). Diode to be treated as e-waste, as stated earlier.
Hazardous Materials to Consider
Silicon
Gas Lasers
Active Concern
Many of these will have a glass or metal plasma tube. The tube can contain beryllium (Be) oxide in a ceramic form, safe for handling unless broken up, in which case it will then generate Be dust (Be dust will have to be handled as hazardous waste). Many gas lasers also contain extensive windings of copper (i.e., Spectra Physics model 2016–2080). Argon ion lasers can also have an internal electrical capacitor.
Common Types of Gas Lasers
Argon laser
Argon ion laser
Carbon dioxide laser
Copper vapor laser (rarely found, contain copper core)
Helium–cadmium laser
Helium–neon laser
Krypton laser
Nitrogen laser
Excimer laser (see Excimer Lasers section)
Disposal
Remove power cord from unit. Crack glass tubes in a well-vented area (cracking of one end is sufficient). Metal plasma tubes should be sent to Hazardous Waste Group for disposal. Common examples of this are the Spectra Physics laser models 160, 163, 177, 183D, 185, and 185F. Any internal optics are to be removed, placed in a ziplock bag, labeled, and sent to the LSO for possible reuse by other laser users.
Hazardous Materials to Consider
Argon
Carbon dioxide
Cadmium
Neon
Krypton
Nitrogen
Beryllium oxide dust
Solid-State and Rod Lasers
Active Concern
Some of these are on export control list. Circuit boards may contain lead.
Common Solid-State Lasers
Alexandrite laser
Erbium:Glass
Ho:YAG
Nd:YAG laser
Nd:YLF
Nd:YVO4
Ruby laser
Ti:Sapphire
Yb:YAG
Ruby
Disposal
Remove power cord, circuit boards (e-waste), and any obvious optics or crystal rods. Place the optics in a ziplock bag, label the bag, and send it to the LSO. Wear protective eyewear and safety gloves. Small quantity of gallium arsenide can be found in diodes.
Of the laser systems noted earlier, most contain Rod lasers modules that generally contain xenon or krypton arc Flash Lamps that serve as the excitation mechanism for the laser medium. Keeping in view the nature of these components, extreme care needs to be taken when handling the flash lamps as they can potentially explode and/ or break upon removal. Treat like glass bulb waste.
Hazardous Materials to Consider
Alexandrite
YAG
Gallium arsenide
BIBLIOGRAPHY
Marshall D. “Laser Disposal, How and Where,” Lawrence Berkeley National Laboratory, 2010. Available at: http://www-afrd.lbl.gov/lsow/LSOW_PDF/7_2_Marshall.pdf.