Appendix 1 13
“L aser-Free” Exposure Distance (LFED) - Beyond this distance, the beam is 50 nW/cm2 or less – di m enough that it is not expected to cause a distraction.
V isible/non-visible determination - Determine whether one or more of the laser wavelengths are visible (in the range 400-700 nm). If the laser is outside the visible range, enter “N/A (non-visible laser)” in all SZED, CZED, and LFED blocks. If the laser is visible, then perform the SZED, CZED, and LFED calculations.
I MPORTANT - For some visible pulsed lasers, the SZED, CZED, and LF ED may be ca lculated to be less (shorter distance) than the NOHD. If this is the case, for safety reasons do not enter the dist ance numbers in the applicable block. Instead, you must enter that the distance is “Less than NOHD.” This is because in this case, the NOHD (eye-damage distance) would be the most important for calculating safety distances and airspace to be protected.
N OHD (Slant Range) – Extensive methodology on determining hazard distances is contained in the ANSI Z136 series of standards. For beams with a small beam diameter (< 1 cm), equations 6.1 through
6.3 provide a simplified method. To determine the Nominal Ocular Hazard Distance slant range (SR) in feet, use Equation 6.1 for Single Pulse or Repetitively Pulsed less than 13 kHz (6.5 kHz for 1050 to 1400 nm). Use Equation 6.2 for Continuous Wave or Repetitively Pulsed greater than 13 kHz (6.5 kHz for 1050 to 1400 nm).
Equa tion 6.1 HMPE QNOHD ×× = 27 . 1 8 . 32φ
Where:
φ = Beam Divergence (mrad) Q = Pulse Energy (J) MPEH = MPE per pulse in J/cm2
32.8 = Conversion factor used to convert centimeters into feet, and radians into milliradians.
E quation 6.2 EMPENOHD Φ ×× = 27 . 1 8 . 32φ Whe re:
φ = Beam Divergence (mrad) Φ = Average Power (W) MPEE = MPE in W/cm2
32.8 = Conversion factor used to convert centimeters into feet, and radians into milliradians (0.0328 ft/cm) E xample: A 40-watt CW laser has a beam divergence of 1.5 milliradians Given:
φ = 1.5 mrad Φ = 40 W MPEE = 0.0026 (2.6 mW/cm2, from Table 2)
Appendix 1 14 Appendix 1 S olve Equation 6.2:
. ft 8 . 061 , 3 140 87 . 21 19536 87 . 210026 . 040 27 . 1 8 . 32 = × = × =×× =φNOHD Vi sual Effect Protection Distances (PDs) - If the laser has no wavelengths in the visible range (400-700 nm), enter “N/A (non- visible laser)” in all blocks under “Visual Effect Distances.” For a visible laser, to calculate the visual protection distance in feet you must calculate equation 6.3 thr ee times, using different values of EL (exposure level) each time. These distances are then the SZED, CZED, and LFED.
E quation 6.3 ELPD VCP27 . 18 . 32 Φ ×× =φ Wh ere:
φ = Beam Divergence (mrad) ΦVCP = Visually Corrected Power (from form)
32.8 = Conversion factor used to convert centimeters into feet, and radians into milliradians (0.0328 ft/cm) EL = 1.0×10-4 W/cm2 (100 µW/cm2) when calculating slant range for Sensitive Zone Exposure Distance (SZE D) EL = 5.0×10-6 W/cm2 (5 µW/cm2) when calculating slant range for Critical Zone Exposure Distance (CZED) EL = 5.0×10-8 W/cm2 (50 nW/cm2) when calculating slant range for Laser Free Exposure Distance (LFED) So urce: The eq uations above are derived from ANSI Z136.1 and have been re-expressed to a simpler form as follows: Beam divergence (φ) is entered in milliradians, making the first ANSI fraction 1,000/φ instead of 1/φ. The radical (square ro ot) si gn is used instead of raising to a power of 0.5. Under the ra dical, the ex pression 4/ π is reduced to 1.27, while beam diamet er (a 2) is not used since its contribution to the ove rall slant range distance is negligible. ANSI results are in cm; to convert to FAA’s desired feet, a conversion factor of 0.0328 is used (1 cm = 0.0328 ft). There are now two numeric constants, 1,000 (from the milliradians fraction) and 0.0328, which are multiplied into a single constant, 32.8, to give results in f eet. For results in cm, use “1,000” as the constant; for results in meters, use “10.”
HOR IZONT AL DISTANCE is the distance along the ground. For example, if a beam’s power drops to 100 µW/cm2 at 1,000 feet, and the beam is elevated at 30° above horizontal, the ground distance where 100 µW /cm2 is reached is 866 feet (1,000 x cos (30°)). Note that the horizontal distance uses the minimum elevation angle.
Appendix 1 15 Cal culate the horizontal distance using the equation:
HD = PD × (cos(Minimum Elevation Angle)) HD = Horizontal distance. The units are the same as for the Slant Range. If SR is in feet, then HD will also be in feet.
SR = Calculated Slant Range for NOHD, SZED, CZED, and LFED respectively.
Minimum Elevation Angle = Minimum elevation angle of laser beam as provided on form.
VE RTICAL DISTANCE is the distance above the ground. In the exam ple above, the bea m’s power drops to100 µW /cm2 at 500 feet ( 1000 x sin(30°)) above the ground. Note that the ve rtical distance uses the maximum elevation angle. Calculate the vertical distance using the equation.
V D= PD × (sin (Maximum Elevation Angle)).
VD = Vertical distance. The units are the same as for the Slant Range(feet).
SR = Calculated Slant Range for NOHD, SZED, CZED, and LFED respectively.
Maximum Elevation Angle = Maximum elevation angle of laser beam as provided on form.
15. CA LCULATION METHOD - List the method by which the calculations were performed.
Appendix 1 16 TABLE 1. SINGLE PULSE SELECTED MAXIMUM
PERMISSIBLE EXPOSURE (MPE) LIMITS Wavelength (nm) Exposure Duration (sec) MPE (J/cm2) Ultraviolet 180 to 400 10-9 to 10 Reference American National Institute Standard ( ANSI) Z136 series Visible 400 to 700 <10-9 10-9 to 5×10-6 5×10-6 to 10 Reference ANSI Z136 series
0.2×10-6
1.8×t0.75×10-3 Infrared 700 to 1050 <10-9 10-9 to 5×10-6 5×10-6 to 10 Reference ANSI Z136 series
0.2×CA×10-6
1.8×CA×t0.75×10-3 1050 to 1400 <10-9 10-9 to 13×10-6 13×10-6 to 10 Reference ANSI Z136 series
2.0×CC×10-6 9×CC×t0.75×10-3 1400 to 1500 <10-9 10-9 to 10-3 10-3 to 4 10 Reference ANSI Z136 series
0.3
0.56×t0.25 + 0.2
1.0 1500 to 1800 <10-9 10-9 to 10 10 Reference ANSI Z136 series
1.0
1.0 1800 to 2600 <10-9 10-9 to 10-3 10-3 to 10 10 Reference ANSI Z136 series
0.1
0.56×t0.25
1.0 2600 to 10,000 <10-9 10-9 to 10-7 10-7 to 10 10 Reference ANSI Z136 series 10×10-3
0.56×t0.25
1.0 To f ind CA:
For wavelength = 700 to 1050nm, CA = 100.002 (wavelength-700) Example 1 Laser wavelength is 850nm; CA = 100.002(850-700) = 100.002*150 = 100.3 = 1.995 Example 2 Laser wavelength is 933nm; CA = 100.002(933-700) = 100.002*233 = 100.466 = 2.924 To find CC:
For wavelength = 1050 to 1150nm, CC = 1.0 For wavelength = 1150 to 1200nm, CC = 100.018 (wavelength-1150) For wavelength = 1200 to 1400nm, CC = 8.0 Example 3 Laser wavelength is 1175nm; Cc = 100.018(1175-1150) = 100.018*.25 = 10.25 = 2.8 To find t: “t” is the pulse duration in seconds.
Appendix 1 17 TABLE 2. CW MODE MAXIMUM PERMISSIBLE EXPOSURE (MPE) LIMITS Values are for selected wavelengths for unintentional viewing.
Wavelength (nm) MPE (W/cm2) Ultraviolet 180 to 400 Reference American National Standards Institute ANSI Z136 series Visible 400 to 700 2.6x10-3 Infrared 700 to 1050 (2.6x10-3) x CA 1050 to 1150 13x10-3 1150 to 1200 (13 x10-3) x CC 1200 to 1400 .1 1400 to 10,000 0.1 S ee Table 1 for correction factors of CA and CC.
Example 1 Laser wavelength is visible; MPE = 0.0026 W/cm2 Example 2 Laser wa velength is 850nm;
( ) ( ) 1995 101010 3 . 0700 850 002 . 0700 002 . 0A = === −−λC 233 A 3 cmW 10 2 . 5 995 . 1 10 6 . 210 6 . 2 −−−− ⋅ × = × × = × × =CMPE “Unintentional vie wing”: Unintentional exposure on aircraft is expected to be no more than 0.25 s due to natural relative motion between the beam and aircraft related to wind and other stabilization issues.
Source: ANSI Z136.1 Tables 5 and 6.
Appendix 1 18 T ABLE 3. VISUAL CORRECTION FACTOR FOR VISIBLE LASERS Use for visible lasers only (400-700 nm).
Laser Wavelength (nm) Visual Correction Factor (VCF) 400 410 420 430 440 450 460 470 480 490 500 510 520 530 540 550 555 560 570 580 590 600 610 620 630 640 650 660 670 680 690 700
4.0 x 10-4
1.2 x 10-3
4.0 x 10-3
1.16 x 10-2
2.30 x 10-2
3.80 x 10-2
5.99 x 10-2
9.09 x 10-2
1.391 x 10-1
2.079 x 10-1
3.226 x 10-1
5.025 x 10-1
7.092 x 10-1
8.621 x 10-1
9.524 x 10-1
9.901 x 10-1
1.0 x 100 (VCF=1)
9.901 x 10-1
9.524 x 10-1
8.696 x 10-1
7.576 x 10-1
6.329 x 10-1
5.025 x 10-1
3.817 x 10-1
2.653 x 10-1
1.751 x 10-1
1.070 x 10-1
6.10 x 10-2
3.21 x 10-2
1.70 x 10-2
8.2 x 10-3
4.1 x 10-3 To find the Visually Corrected Power (VCP) for a specified wavelength, multiply the Visual Correction Factor (VCF) for the wavelength (from the table above) by the Average Power. If the laser’s wavelength falls between two table entries, use the more conservative (larger) value of the two resulting VCFs.
Exam ple 1: A frequency-doubled YAG laser emits 10 watts of 532nm continuous wave light. From the table, 532 is between 530 and 540; use the more conservative (larger) Visual Correction Factor of 540nm:
9.524 x 10 -1. Multiply the VCF of 0.9524 by the A verage Power of 10 watts, to obtain the Visually Corrected Power of 9.524 watts.
Appendix 1 19 TA BLE 3. VISUAL CORRECTION FACTOR FOR VISIBLE LASERS (Continued) E xample 2: An 18-watt argon laser emits 10 watts of 514 nm light, and 8 watts at 488nm light, both continuous wave. Cal culate each wavelength separately, and t hen add the resulting Visually Corrected Powers together.
1 0 watts at 514nm: From the table, 514 is b etween 510 and 520, use the more conservative (larger) VCF of 52 0nm:
7.092 x 10-1. Multiply the VCF of 0.7092 by the Average Power of 10 watts to obtain the Visually Corrected Power of
7.092 watts.
8 watts at 488nm: From the table, 488 is between 480 and 490; use the more conservative (larger) VCF of 490nm:
2.079 x 10 -1. Multiply the VCF of 0.2079 by the Average Power of 8 watts, to obtain the Visually Corrected Power of
1.6632 watts.
Finally, add t he t wo VCPs together: 7.092 + 1. 6632 = 8 .7552. T he 18- watt laser in th is e xample has a Visually Corrected Power of only 8.7552 watts.
Note: Example 1 is the 10-watt YAG which appears brighter to the eye (9.5 WVCP) than an 18-watt argon (8.8 WVCP).
Source: The Visual Correction Factor used in this table (CF) is the CIE normalized efficiency photopic visual function c urve for a s tandard observer. The illuminan ce (lm•cm-²) is the measured irradiance multiplied by CF and 683. The effective irradiance is the actual (measured) irradiance multiplied by CF. The effective irradiance (W⋅cm-2) multiplied by 683 lm⋅W-1 is the illuminance (lm⋅cm-2).
Appendix 1 20 LA
SER FREE ZONE
Appendix 1 21
AIRSPACE FLIGHT ZONES
1. L aser Fr ee Zone (LFZ): Airspace in the immediate proxim ity of the airport, up to and i ncluding 2,000 feet AGL, extending 2 nautical miles in al l directions measured from the runway centerline.
Additionally, the LFZ includes a 3nm extension, 2,500 feet each side of the extended runway cen terline, up to 2,000 feet AGL of each useable runway surface. The level of laser light is restricted to a level that should not cause any visual disruption.
2. C ritical Flight Zone (CFZ): Airspace within a 10-nautical-mile (nm) radius of the Airport Reference Point (ARP), up to and including 10,000 feet AGL, where a l evel of laser l ight is restricted to avoid flashblindness or afterimage effects.
3. S ensitive Flight Zone (SFZ): Airspace outside the Critical Flight Zone(s) that authorities (e.g., FAA, local depart ments of aviation, m ilitary, etc.) have id entified that must be protected from flashblindness or afterimage effects.
4. Nor mal Flight Zone (NFZ): Airspace not defined by the Laser Free, Critical, or Sensitive Flight Zones.
Appendix 1
AIRSPACE FLIGHT ZONES
ELEVATION
SENSITIVE FLIGHT ZONE CRITICAL FLIGHT ZONE 8000 5pw/cmz 2000: LASER FREE ZONE 50nW/cm₴ ** 31m 2nm 20m 3rm 10mm 10nm
AIRPORI REFERENCE POINT (ARF) * Runway length varies per airport AOL is bosed on published airport elevation * To be determined by regional evaluation and/or local airport operations.
Appendix 2 23 Appendix 2: FEDERAL AVIATION ADMINISTRATION SERVICE
CENTER ADDRESSES Attn: Manager, Operations Support Group Eastern Service Center, AJV- E2 1701 Columbia Ave.
College Park, GA 30337 9-AT O-ESA-OSG-Lasers- Searchlights@faa.gov
NY, WV,
VA, MD,
PA, NJ, DE, WASH.
DC, RI,
MA, CT,
VT, NH,
GA, AL,
MS, FL,
KY, TN,
NC, SC, ME Attn: Manager, Operations Support Group Central Service Center, AJV- C2 10101 Hillwood Parkway Fort Worth, TX 76177 9-AS W-Operations-Support- Lasers@faa.gov
IA, NE,
KS, MO,
OH, MI,
IL, IN,
MN, WI,
ND, SD,
TX, AR,
OK, NM, LA Attn: Manager, Operations Support Group Western Service Center, AJV- W2 1601 E. Valley Road Renton, WA 98057 9-ATO-WSA- OSG.Lasers@faa.gov
AK, WA,
OR, ID,
MT, WY,
UT, CO,
CA, NV, AZ, HI
Appendix 2 24
GLOSSARY
a) A fterimage – A reverse contrast shadow image left in the visual field after an exposure to a bright light that m ay be distracting and disruptive, and may persist for several minutes.
b) Ce nter for Devices and Radiological Health ( CDRH) – An office of the FDA concerned with enforcing compliance with the Federal requirements for laser products including laser light shows.
c) Dem onstration – Any laser product designed or i ntended for purposes of visual display of laser beams, for artistic composition, entertainment, and /or advertising display (see 21 CFR 1040.10(b) 13). Any d emonstration laser in excess of 5 mW requires a variance from the CDRH.
d) D ivergence – The increase in the diameter of t he laser be am with distance f rom the exit ape rture.
Divergence is an angular measurement of the beam spread, expressed in milliradians (mrad). In laser safety calculations, divergence is defined at the points where the irradiance is 37% of the peak irradiance.
e) F lashblindness – Generally, a temporary visual interference effect that persists after the source of illu mination has ceased.
f) F light Safe Lev el – An estimate of the m aximum exp osure of radiant light energy emission (irradiance value) allowed to illuminate an aircraft within specific f light zones.
g) Flig ht Zones – Airspace areas specifically intended to mitigate the potential hazardous effect of laser emissions. These areas may not be contiguous or concentric as the other zones. There are several types of flight zones:
1. L aser Free Zone (LFZ) – Airspace zone where the level of laser light is restricted to a le vel that should not cause any visual disruptions.
2.
Critical Flight Zone (CFZ) – Airspace zone where a level of laser light is restricted to avoid flashblindness o r afterimage effects.
3 . S ensitive Flight Zone (SFZ) – Airspace zone outside the critical flight zones that authorities (e.g., F AA, local departments of aviation, military) have identified that must be protected from the potential effects of laser emissions.
4. Normal F light Zones (NFZ) – Airspace zone not defined by the Laser Free, Critical, or Sensitive Flight.
h) I rradiance – Irradiance is a m eans of expressing the intensity of the beam per unit area, expressed in watts per centimeter squared (W/cm²).
i) Jou le (J) – The International system unit of energy, equal to the work done when a current of one ampere i s passed through a resistance of one ohm for one second.
j) L aser – An acronym for light amplification by st imulated emission of radiation. A laser is a device that produces an intense, directonal, coherent beam of visible or invisible light.
k) La ser Manufacturer – A term that refers to persons w ho make laser products, including those who are engaged in the b usiness of design, a ssembly, or presentation of a laser light show.
l) La ser Safety Officer (LSO) – A designated pe rson who has authority to monitor and enforce t he c ontrol o f laser hazards a nd affect the knowledgeable evaluation an d control of laser hazards.
m ) Laser Operator – A laser operator should be a k nowledgeable person present during laser operation who has been given authority to operate the laser system in compliance with applicable safety standards, subject to direction of the laser safety officer.
n ) Local Laser Working Group (LLWG) – A g roup that, when necessary, is convened to assist the regional air traffic division in evaluating the potential effect of laser emissions on aircraft operators in the local vicinity of the proposed laser activity.
o ) Maximum Permissible Exposure (MPE) – The level of la ser radiation to which a person may be exposed without hazardous effect or adverse biological change in the eye or skin. In general, MPE is expressed as mW/cm² or mJ/cm².
p) Milliradia n (mrad) – A measure of angle used for beam divergence.
q) N ominal Ocular Hazard Di stance (NOHD) – T he ma ximum distance from the laser system beyond which the laser-beam irradiance does not exceed the MPE for that laser.