Table of Contents: Section 1 Introduction to LSOP Section 2 Personnel Section 3 Laser inventory Section 4 Laser Hazards & Hazard mitigation Section 5 Laser Environment Section 6 Written Procedures Section 7 Laser Controls Section 8 Required Calculations (MPE, OD, NHZ) Section 9 Required Schematics (Laser Area, Table layout, Interlock Schematic) Appendix A- Lock, Tag, & Try Appendix B- Periodic Safety check Appendix C - Eyewear selection chart Section 1 Introduction to LSOP This Laser Standard Operating Procedure (LSOP) addresses all aspects of safety and conduct specific to the operation and maintenance of the lasers used in building 58,room 129C. Commonly referred to as: ITS Laser Room. The modus operandi of the laser room is unique in the fact that it permits operational testing of all lasers owned by the source group. When a specific laser is set up for operation, the training slate for the room is wiped clean. New training is given for each experimental setup. In addition, the access keypad number for the room interlock and the electronic key locker is changed to a new number by the LSS for each experiment. The new access number is given to personnel only after completion of lab specific training for the latest experiment. Aspen training records will be updated during each experiment to reflect the latest personnel authorized to run the laser system and eliminate permissions of personnel trained for the previous experiment. Keys for all lasers, operational and off-line, are kept in the electronic key locker unless the laser is transported to another class 4 laser area for operation. The Laser System Supervisor (LSS) is John Hansknecht. email: hansknec@jlab.org Extension: 7096 A copy of this LSOP is posted online at: http://www.jlab.org/inj_group/laser_safety/its_laser_safety.html and at the following physical location: Bldg 58 Room 129 safety bulletin board Section 2 Personnel A list of authorized laser personnel is maintained in the online Jlab training system under title SAF156. A Laser Worker must have completed SAF156 Laser Safety Training for ITS laser room. This means the Laser Worker has: a) been qualified by Jefferson Laboratory Occupational Health Physician as detailed in Section 6410 of the EH&S manual, 2
b) taken a laser safety course administered by the safety officers at Jefferson Laboratory, c) read Section 6410 of the EH&S manual, d) read and understood this LSOP, e) received walkthrough training with the LSS for the experiment to be performed. Accidental Eye Exposure: Accidental eye exposure to a laser beam requires immediate medical attention whether injury is apparent or not. If possible, the individual should remain and be transported in the upright position. Clothing Requirements: Laser workers must not wear jewelry or clothing that presents a specular reflection hazard. Spectator Protection Requirements: Laser Workers may escort Spectators in an interlocked laser area only after ensuring that the spectator is wearing appropriate safety eyewear. Spectators must have received prior permission from the Laser System Supervisor before entering the interlocked laser area. Section 3 Laser Inventory The ITS laser room is a testing and evaluation facility for all lasers owned by the source group, therefore all source group lasers are listed in inventory even though they not be in active use within the space. Many of our lasers are in use within other class 4 laser areas, but may be brought to the ITS laser room for repair and testing. Description: Diode lasers - Used as a direct optical source for an experiment on the laser table or used as to seed other lasers for wavelength or temporal control. Type of Laser / Class Semiconductor diode laser / Class 3A and 3B Ultimate manufacturers are unknown. Diodes are supplied by Thorlabs, Qphotonics, etc. Multiple model numbers. This information is not consequential for safety. All diodes are treated with equal concern based on power, wavelength, and beam shape. Serial Numbers Diode lasers are easily damaged and frequently replaced. Furthermore, vendors do not mark serial numbers on the diode housings because they are often too small. For this reason, serial numbers of seed lasers are not recorded in this LSOP. Wavelength range 630nm,700-900nm, 1064nm, 1560nm Power Range Up to 200mW. Worst case= pulsed at 250 MHz with 10ps Gaussian. May also operate CW. 3mm Divergence (uncollimated, typical) 10 degrees parallel, 30 degrees perpendicular to laser junction. 3
Description: Ti-Sapphire laser. Modelocked, wavelength tunable Type of Laser / Class Ti-Sapphire / Class 4 TimeBandwidth, Inc. Tiger Serial Numbers 116,117,118, 122 Wavelength range 750-900 Power Range Up to 2W Worst case = 31MHz rep rate with 10ps Gaussian..3mm Divergence (uncollimated, typical) 0.35mrad +/- 10% Description: Pump source for Ti-Sapphire lasers. May also be used as a direct source for an experiment requiring 532nm CW light. Type of Laser / Class Frequency-doubled Nd:YVO4 / Class 4 Jenoptik and Coherent Jenoptik (none) Coherent Verdi-V10 Serial Numbers 201,218,312, 248902, V10-A0436, V10-A0024 Wavelength range 532nm Power Range Up to 11 Watts CW 2.25mm Divergence (uncollimated, typical) 0.35mrad +/- 10% Description: Fiber Laser Amplifier at 1560nm Type of Laser / Class Fiber, single mode (class 4 at fiber output) Keopsys & IPG Keopsys KPS-BT2-PEYFA-1560-PB-060-PM- FA. IPG EAR-5K-C-LP-SF. Serial Numbers 5090325, PA0605238, PA0605747, PA0706297 Wavelength range 1560nm Power Range Up to 6 Watts Worst case = 250MHz with 1.7mm Divergence (uncollimated, typical) 0.35 mrad +/-10% Description: Fiber Laser Amplifier at 1064nm Type of Laser / Class Serial Numbers Wavelength range Fiber, single mode (class 4 at fiber output) IPG YAR-5K-1064-LP-SF, YAR-50K-1064-LP- SF-J PA0605581, PA0706590 1064nm 4
Power Range Up to 50 Watts Worst case = 250MHz with.7mm Divergence (uncollimated, typical) 0.35 mrad +/- 10% Description: Frequency doubling apparatus for creating 780nm from 1560nm * Type of Laser / Class Frequency doubling crystal. (Class 4) Jlab N/A Serial Numbers N/A Wavelength range 1560nm input / 780nm output Power Range Up to 3 Watts delivered at 780nm Worst case = 250MHz with 2.5mm Divergence (uncollimated, typical) 0.35 mrad +/- 10% Description: Frequency doubling apparatus for creating 532nm from 1064nm * Type of Laser / Class Frequency doubling crystal. (Class 4) Jlab N/A Serial Numbers N/A Wavelength range 1064nm input / 532nm output Power Range Up to 25 Watts delivered at 532nm Worst case = 250MHz with 1 mm Divergence (uncollimated, typical) 0.35 mrad +/- 10% * The frequency doubling apparatus is not a laser, but it modifies the wavelength delivered by the fiber lasers. This change in wavelength requires MPE calculations for eye and skin to cover both the fundamental and second harmonic wavelengths. Section 4 Hazards & Hazard mitigation Laser Specific Hazards The laser(s) described in section 3 may produce optical energies that can damage the eyes and burn skin. Refer to section 8 for skin and eye MPE calculation results. The laser eye and skin hazards are mitigated by the following the procedures detailed in section 6- Alignment Guidelines. These procedures specify the use of appropriate eyewear based on the MPE calculations and provide guidance to avoid skin exposure. Hazard mitigation for non-affected personnel is provided by engineered safety controls in the form of an interlocked laser safety system as detailed in section 7. 5
Non-Laser Hazards Historically we have listed high voltage as a hazard associated with lasers. Since the advent of solid state lasers, this is no longer an issue. All lasers used in this space are operated with housings that contain all hazardous voltage. Any other item requiring high voltage, (e.g. Pockels cells) will have electrically shielded connections making the high voltage inaccessible to the worker during operation. Section 5 Laser Environment The laser systems are located on one 4 x 8 optical table. The path of the laser beam should be maintained within the perimeter of the table and within a height of 8 above the table surface. Optical baffles 8 high are fixed along the perimeter of the table protecting personnel sitting at the desk workstation. When the laser interlock is engaged, the laser room entry door is magnetically locked and a yellow beacon illuminates at the entrance to the laser room. Access code for the lock is given to laser workers qualified for the experiment. All Class 4 laser keys are kept in the electronic key safe. The code for this safe is changed for each experiment, so only the active qualified workers have access to the laser keys. Keys shall be removed and placed in the safe when the laser is not scheduled for operation within the shift. The laser controlled area is shown on drawing attached in section 9. This drawing shows beam location in relation to users. It also shows a typical table layout. The laser system supervisor will give one-on-one training to lab users during the qualification process. This training will discuss the layout and hazards presented by the running experiment. The ultimate beam target is dependent upon the experiment. The final termination point must be rated to receive maximum deliverable power from the laser with low back scatter. The laser(s) described in section 3 will be run one at a time or in combination only when the combination falls within the protective wavelength band of the selected eyewear. In addition to laser hazards, the following potential hazards exist: Fire and Smoke. Care must be taken to ensure beam does not contact materials that are flammable or capable of generating smoke. Section 6 Written Procedures In normal use, the laser system described by this LSOP is used for laser research. The ultimate goal of operation is to find a laser that is capable of producing the proper beam power and quality for production running elsewhere at the lab. Some experiments within this laser room are dedicated to testing various laser optical control components. Since the laser room has a dynamic experiment schedule, training is given to key personnel 6
specific to the experiment at hand. The entry code on the defeatable interlock entryway and electronic key safe is changed for each experiment. This ensures that only personnel that have been trained for the current experiment can gain access during laser operation. Maintenance & Service Routine maintenance of the laser systems consists of realignment and cleaning. These procedures are described in laser technical manuals. Maintenance requiring replacement of parts will be carried out by an escorted vendor representative or qualified JLAB personnel. Maintenance may require Lock-Tag-& Try as described in Appendix A. Laser eyewear shall be routinely inspected for damage. Alignment Procedures The following techniques for laser alignment will be used to help prevent accidents during alignment. Procedural Considerations 1. Watches, rings, dangling badges, necklaces, reflective jewelry are taken off before any alignment activities begin. Use of non-reflective tools should be considered. 2. Access to the room/area is limited to authorized personnel only. 3. Consider having someone present to help with the alignment. 4. All equipment and materials needed are present prior to beginning the alignment 5. All unnecessary equipment, tools, combustible material (if fire is a possibility) are removed to minimize the possibility of stray reflections and non-beam accidents. 6. Persons conducting the alignment have been authorized by the LSS Alignment Methods to be used for this laser system: 1. There shall be no intentional intrabeam viewing with the eye. 2. Co-axial low power lasers should be used when practical for alignment of the primary beam. 3. Reduce the beam power through the use of ND filters, beam splitters and dumps, or reducing power at the power supply. Avoid the use of high-power during alignment. 4. Laser Protective Eyewear shall be worn at all times when lasers are operating. 5. Beam Control- the beam is enclosed as much as practical, optics/optics mounts are secured to the table as much as practical, beam stops are secured to the table or optics mounts. 6. Areas where the beam leaves the horizontal plane shall be labeled. 7. Any stray or unused beams are terminated. 8. Invisible beams are viewed with IR/UV cards, business cards or card stock, craft paper, viewers, 3x5 cards, thermal fax paper, Polaroid film or similar technique. Operators are aware that specular reflections off some of these devices are possible, and that they may smoke or burn. 9. Intrabeam viewing is to be avoided by using cameras or fluorescent devices. 7
Off-normal and Emergency Procedures In Case of Fire, exit the space immediately and pull the fire alarm located at the test lab exit doors. A smoke detector within the laser room will disable the laser power supplies. Notify the LSS after mitigating the emergency. Section 7 Laser Controls and Laser Room Interlock Laser Safety Eyewear Smoke Detector Laser Beacons To be worn at all times during laser operation. Refer to Appendix C Eyewear selection chart for OD/ wavelength selection. Personal prescription laser eyewear may be in the possession of the individual in lieu of storage in the laser eyewear bin. The eyewear bin will be kept clear of all eyewear that is not appropriate for the active experiment. The laser eyewear shall be kept clean and removed from service if damaged. Smoke and fire detectors disable the laser in case of smoke or fire. Provide a visual indication of the state of the laser interlock to personnel approaching the laser area. Their operation is described in the interlock section. Laser Start-Stop Class 3B and Class 4 lasers are not able to run unless the room interlock is energized. Once the room interlock is set, the lasers may be started and stopped manually or via computer control. Laser Enclosures Laser Interlock Laser operation key The class 4 laser room permits open beam class 4 operations within the space, however whenever a laser has a class 1 enclosure, the enclosure should be kept intact unless an active alignment necessitates entry to the enclosure. Laser interlock training is provided during the training walkthrough. All Class 3B and Class 4 lasers will be interlocked via AC power, shutter, or low voltage interlock connection to the room interlock system. Unauthorized access is prevented via the magnetic lock on the entry door. If this lock is bypassed with brute force, the interlock will instantly trip. Pressing a crash button in the laser room or entrance enclave will break the interlock. An alarming smoke detector will break the interlock. Lasers operating keys shall be removed and placed in the electronic key safe when the laser operation is not expected during the shift. 8
Laser Wavelength Section 8 Required Calculations (MPE / NHZ / OD) MPE, OPTICAL DENSITY, AND NOMINAL HAZARD ZONE Calculations Injector Test Stand Laser Room - Room 129 C The MPE, nominal hazard zone, and OD requirement for the eyewear are calculated according to the ANSI Standard for the Safe Use of Lasers A136.1 2000, using software package Lazan version 3.6 software supplied by Rockwell Laser Industries. Laser parameters needed to calculate these values for the ITS Laser system: Assumptions: Beams always collimated. Beams are circular. CW beams: exposure 10 seconds for IR lasers, 0.25 seconds for visible lasers 7mm limiting aperture For diodes: information usually given for diodes includes the divergence for the uncollimated beam and the diameter of the collimated beam. The information that is required to calculate the nominal hazard zone is related to the worst case, or collimated beam. The equation used to determine the divergence of the collimated beam is: 1.27 * (wavelength in microns)/(beam waist diameter in mm) Results: Worst case pulsed conditions Max average power at stated pulse conditions MPE/eye (mw/cm 2 ) Collimated Beam Diameter (mm) NHZ (meters) Required OD (eyewear) 532nm CW 11 Watt 2.55 2.25 3000 4.05 532nm 250 MHz with 25 Watt 2.55 2.25 4500 4.41 630 nm 250 MHz with 700 nm 250 MHz with 760 nm 250 MHz with Tunable laser or diode with band of 700-900 nm 1064nm 1560nm 31 MHz with 250 MHz with 250 MHz with 200mW 2.55 3 400 2.31 200mW 1 3 400 2.31 200mW 1 3 560 2.6 5 Watt 1 2.25 238 3.71 50 Watt 5.00 3 3500 4.41 6 Watt 100 1 620 2.79 All calculation sheets are stored online at http://www.jlab.org/inj_group/laser_safety/its_laser_safety.html 9
Section 9 Required Schematics (Laser Area, Interlock Schematic) Figure 1. Laser Room and optical table layout (table layout is subject to change based on experiment). 10
Figure 2: Overview of interlock operation. Red Circuits will secure laser operation in an emergency Magenta circuits warn of laser operation (actual warning lights are yellow) Green circuit enables interlock system Safety relay output is interfaced to the class 3B and class 4 lasers using one of the three approved interlock circuits, FLPPS dry contact, Shutter, or AC power. Appendix A Lock, Tag & Try All lasers used in the room have a corded plug connection to the AC utility. Lock and Tag procedures are not required once the unit is unplugged and cord end is maintained within sight of the worker performing maintenance. It is unlikely that Jlab personnel would be working on the internals of commercial laser systems, but if the case arises the work would only be performed by a qualified electrical worker following proper troubleshooting procedures. 11
Appendix B Periodic Safety check Periodic Laser Room Safety Verification (every 6 months or upon major re-configuration) ITS Laser Room LSOP is posted in the ITS Control Room. Permanent laser safety signs are posted. Laser eyewear clearly marked with proper OD/wavelengths are available for the active experiment. (prescription eyewear may be with owner) Eyewear is clean and free of damage or defects that would interfere with intended safety protection. Class 3B and 4 Lasers cannot be turned on without the laser control key. Once the laser interlock is complete the door is magnetically locked and the entry code and exit button work properly. Laser beacon illuminates the Laser Room enclave when the interlock is engaged. All crash buttons function to secure the interlocked laser. Laser interlock must be reset manually when the laser interlock is tripped. Calibrated laser power meter available. Smoke detector laser interlock functions. SAF 156 database reflects proper personnel qualified for the active experiment. Laser room entry code has not been compromised and is shared only with users qualified for the active experiment LSS: Date: 12
Appendix C Eyewear selection chart Laser Wavelength Worst case pulsed conditions Max average power at stated pulse conditions 532nm CW 11 Watt 4.05 532nm 250 MHz with 10ps 25 Watt 4.41 Gaussian 630 nm 250 MHz with 10ps 200mW 2.31 Gaussian 700 nm 250 MHz with 10ps 200mW 2.31 Gaussian 760 nm 250 MHz with 10ps 200mW 2.6 Gaussian Tunable laser or diode with band of 700-900 nm 31 MHz with 10ps Gaussian 5 Watt 3.71 1064nm 1560nm 250 MHz with 10ps Gaussian 250 MHz with 10ps Gaussian 50 Watt 4.41 6 Watt 2.79 Required OD (eyewear) 13