Disclaimer & Safety

Radiation Safety

When experimenting with ionizing radiation, like X-rays or Gamma-rays, diminishing your and everyone else’s exposure should be the first priority. Ionizing radiation can have serious health effects at high biologically effective doses including skin burns, an increase in cancers, radiation sickness, and even death.

There are three components that figure into the total radiation dose: time, distance, and shielding.

  • Time: The less time you spend exposed to radiation the lower your dose. When experimenting, make sure you know exactly what you need to get done with the radiation. If necessary, go through a dry run practicing all your motions without the radiation. Only use the radiation when you have worked out all the other potential problems with your experimental procedure.
  • Distance: Like most other physical phenomena, radiation decreases with distance in accordance with the inverse square law. This means that the further away you are from the source of the radiation, the less radiation you’ll be exposed to. Try to plan your experiments so that you, and anyone else around, are standing as far away from the radiation source as possible.
  • Shielding: As ionizing radiation passes through matter, the intensity of the radiation is diminished. Thus, to protect yourself from radiation you should erect a barrier or shield. However, the material you use matters significantly; some materials reduce the intensity of radiation more than others. Every material has a “halving thickness.” This is the thickness required to reduce the radiation intensity by half. So if the halving thickness of a material is 1 inch, then a 1 inch thick sheet will cut the radiation to 50%. Two inches will cut the radiation to 25%, 3 inches to 12.5%, and so forth. Traditionally lead is used for shielding because it has a very low halving thickness (0.4 inches). Before working with radiation, erect the shielding. When working with radiation, staying behind the shielding can be an effective way of diminishing your radiation exposure.

Laser Safety

Many scientists involved with lasers agree on the following guidelines:

  • Everyone who uses a laser should be aware of the risks. This awareness is not just a matter of time spent with lasers; to the contrary, long-term dealing with invisible risks (such as from infrared laser beams) tends to reduce risk awareness primarily due to complacency, rather than to sharpen it.
  • Optical experiments should be carried out on an optical table with all laser beams travelling in the horizontal plane only, and all beams should be stopped at the edges of the table. Users should never put their eyes at the level of the horizontal plane where the beams are in case of reflected beams that leave the table.
  • Watches and other jewelry that might enter the optical plane should not be allowed in the laboratory. All non-optical objects that are close to the optical plane should have a matte finish in order to prevent specular reflections.
  • Adequate eye protection should always be required for everyone in the room if there is a significant risk for eye injury.
  • High-intensity beams that can cause fire or skin damage (mainly from class 4 and ultraviolet lasers) and that are not frequently modified should be guided through opaque tubes.
  • Alignment of beams and optical components should be performed at a reduced beam power whenever possible.

High Voltage Safety

  • Work on un-energized circuits if at all possible.
  • Be very careful around live 50/60 Hz electricity, since it requires very little current to injure. Your power supply can kill you!
  • Limit the current and energy to the lowest values possible. Lots of interesting experimentation can be done with low stored electrical energy and low currents of a few mA or even microamperes. Make it a habit to ask yourself if you really need this current or energy.
  • Keep your distance from live high voltage circuits. Since high voltages can breakdown air to connect you to a circuit, keep high voltage circuits in enclosures and behind barricades when in operation.
  • Be sure to properly ground your experiment and your enclosure. Take special care to safely de-energize and ground a circuit before working on it. Know when and how you can end up in the ground path in a circuit and put safeguards in place to eliminate this eventuality.
  • Never work alone, always have a partner who knows your equipment and the risks and hazards involved. That way, you have a second set of eyes to insure safety, and someone who can shut off the power and get help if you are injured.


The authors do not make any representations as to the completeness or the accuracy of the information contained herein, and disclaim any liability for damages or injuries, whether caused by or arising from the lack of completeness, inaccuracies of the information, misinterpretations of the directions, misapplication of the circuits and information or otherwise. The authors, contributors, and owners expressly disclaim any implied warranties and of fitness of use for any particular purpose, even if a particular purpose is indicated in the text.