Flashcards in Laser Safety Deck (28):
Which government agency regulates the classification and control measures Incorporated into laser products?
Conjunctivitis may result from a welding arc due to
UV radiation. The wavelengths responsible for conjunctivitis are 270-280 nm in the UV area of the electromagnetic spectrum.
The most important type of UV for causing cancer from sunlight is
Most biologically effective wavelength for killing microbes by UV
270 nm UVB
Eye exposure to a 1520 to 1570 nm laser results in damage to:
The Cornea. Wavelengths greater than 1400 nm are absorbed in the cornea
Laser wavelengths generally considered retina hazards
400 to 1400 nm
What is the usual unit for measurement of laser radiation
J/cm^2 or W/cm^2
Target organ for consideration of biological damage to humans from laser exposure is the
Eye. Skin is a close second.
Far infrared wavelength
1400nm to 1mm
Near Infrared wavelength
780 to 1400 nm
Visible electromagnetic spectrum
400nm to 780nm
Ultraviolet electromagnetic spectrum
Far: 200-315nm Near: 315-400 nm
Three areas of eye sensitivity
Retina, Lens, Cornea
Wavelengths that put the retina at risk
Visible, IR-A (near)
Wavelengths that put the lens at risk
Wavelengths that put the cornea at risk
UV-B, UV-C, IR-B, IR-C
Class 1 laser
Laser cannot cause injury either because it is too low powered or because of engineered safety controls.
Class 2 laser
May be viewed for less than 0.25 seconds. The aversion response, which leads to a blink in less than 0.25 second, is sufficient to prevent injury to the eye. Max power level = 1 mW
Class 3a laser
Can injure the eye in intrabeam viewing for less than 0.25 seconds ,or viewing a specular reflection for less than 0.25 seconds. Max power level = 5 mW.
Class 3b laser
Same as 3a, except max power level = 500 mW, max radiant exposure = 10 j/cm^2 per pulse. ANSI 'DANGER' Sign.
Class 4 laser
Hazardous to the eyes and the skin during intrabeam and diffuse exposure. Potential fire hazard. Power level >500 mW. ANSI 'DANGER' sign
Aversion response time for visible light
Aversion response time for IR
one Watt is equal to
1 joule per second
Peak Power (Watts)
Radiant exposure (H)