Light Sources and Laser Safety

Light Sources and
Laser Safety
Fred Seeber
Camden County College
Blackwood, New Jersey
This module addresses various nonlaser light sources, such as incandescent lamps, fluorescent
discharge lamps, high-intensity discharge lamps, flashlamps, arc lamps, and LEDs. It will also
discuss in detail laser safety including the human eye, laser hazards, laser safety controls,
maximum permissible exposure, laser safety glasses, and laser accidents. The laboratory
experience at the end of the module will enhance your ability to understand the dangers
associated with lasers, with small and large beam diameters, and with constant power levels.
Prerequisites
Before you work through this module, you should have completed Module 1-1, Nature and
Properties of Light. You should also have a working knowledge of intermediate algebra.
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Objectives
Upon completion of this module, you should be able to:
1. Define the following properties of laser light:
a. Monochromaticity
b. Directionality
c. Coherence
2. Distinguish between the different types of nonlaser light sources and identify their
characteristics.
3. Recognize and avoid various nonbeam hazards, such as electrical and chemical hazards.
4. Label a diagram of the human eye. State the function of each part shown.
5. Match the parts of the eye with the spectral regions to which they are most vulnerable.
6. Given the basic information required, calculate retinal spot size and retinal irradiance.
7. Describe the following laser classifications, based upon the potential hazards:
a. Class 1 laser
b. Class 2 laser
c. Class 3a laser
d. Class 3b laser
e. Class 4 laser
8. Define maximum permissible exposure. State why it’s important.
9. Describe three general types of laser hazard controls.
10. Describe laser-hazard warning signs.
11. Describe the most frequent causes of laser accidents.
12. List five laser safety precautions applicable to all types of lasers.
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Scenario—Laser Safety in a Medical Environment
Joan recently graduated from a two-year photonics program at her local community
college. She accepted a job at City Hospital in Philadelphia as a laser technician.
City Hospital uses CO2, argon, and Nd:YAG lasers for its surgical procedures. Joan
soon discovered that her responsibilities would also include being laser safety
officer (LSO). Joan recalled the discussions she had in school about laser safety
and the laser safety concepts she learned. Because being a laser safety officer is a
major responsibility and critical to the well-being of both the staff and the patients,
the hospital and Joan realized more training would be necessary. The hospital
sponsored Joan’s attendance at a five-day course on medical laser safety given by
the Laser Institute of America in Orlando, Florida. At this course the duties of a
laser safety officer were discussed, including such topics as safety education, laser
hazards and controls, personal protection, medical surveillance, and more. As Joan
begins her duties as LSO, she realizes how important laser safety is for all in the
medical working environment. Good luck, Joan, as a photonics technician and laser
safety officer.
Opening Demonstration
Note: The following demonstration will provide a view of some of the concepts you will
encounter in this module.
Factors that result in the absorption of laser light. In a room or laboratory with reduced
ambient light (light already in room), set up a demonstration as seen in Figure D-1 using a laser
pointer (laser diode), red and blue plastic or glass filters, and a piece of white cardboard or
paper.
Figure