MSU ECE 476 - Lab I Safety & Basic Measurement (6 pages)

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Lab I Safety & Basic Measurement



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Lab I Safety & Basic Measurement

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Pages:
6
School:
Michigan State University
Course:
Ece 476 - Electro-Optics

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Lab I Safety Basic Measurement ECE 476 I Purpose The focus of this experiment is laser light safety and an introduction to the helium neon laser and the optical power meter II Background Laser Safety Lasers and high radiance LEDs may cause eye damage by absorption of light energy inside the retina This potential hazard has been investigated by a number of scientists and national safety organizations These organizations contributed to the recommendation of the International Electro technical Commission IEC in which all major industrial nations have representatives This organization has established maximum permissible exposure limits for light energy The limit establishes the maximum safe radiation levels at the human eye s entrance surface For continuous operation these levels depend on wavelength as shown in Fig 1 below Note that the light energy levels are given in units of irradiance power per unit area Figure 1 Maximum irradiance chart The IEC stipulates that all laser products be classified in order to establish suitable means to protect anyone from dangerous laser light levels Lasers are classified into 4 classes Class 1 laser products are to be inherently safe For example the typical emission limits for class 1 lasers are less than 0 24 mW power and less than 1 28 W cm 2sr 1 radiance at 850 nm These numbers vary with wavelength Class 2 laser products are visible lasers ranging from 400 to 700 nm Within this range the human eye protects itself via the blink reflex assumed to respond within 0 25 seconds The CW power from a class 2 source may be 1mW maximum Class 3A products are not inherently safe For the visible range from 400 to 700 nm the emission limits may be 5 times those of class 2 1 Class 3B products may emit dangerous radiation levels The limitation in CW operation of class 3B lasers is 0 5 watt maximum power within the wavelength range from 315 nm up to l mm Class 4 products produced light levels exceeding those of class 3B limits These lasers are



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