20.309:Safety

Safety

The chief hazards present in the 20.309 Lab come from: laser radiation, chemical and biological materials, and electric potentials. Some simple precautions will make your time in the lab much safer.

Laser safety

Laser radiation chiefly affects eyesight and skin. The lasers we will use in 20.309 are not powerful enough to do much damage to skin; however, all lasers pose a significant threat to your vision if the beam or a reflection of it enters your eye. Even a 1 milliwatt laser pointer — the kind many people carry around on their keychains — has the potential to produce a spot on your retina more than 100 brighter than the sun.[1]

General laser safety practices

• Always know the path of the beam.
• Keep body parts and reflective items (such as jewelry and tools) out of the beam path.
• Do not wear refective jewelry when working with a laser.
• Read the lab manual and know what special precautions must be taken.
• Ensure that you are wearing the correct safety goggles — check the specification markings every time you put them on.
• When in doubt, check with the lab instructor.

Near the beginning of the term, there will be a mandatory laser safety lecture given by the Environment, Health and Safety office. More information may be found in this EHS document and in the lab manuals.

Lasers in 20.309

In 20.309, we will use three types of lasers, as detailed in the table below. Lasers are divided into classes according to their potential for causing harm.[2]

Lab Module	Wavelength	Color	Power	Class	Safety Measures
Atomic Force Microscopy	635	Red	2 mW	IIIa	Do Not Stare Into Beam
Fluorescence Microscopy	532	Green	5 mW	IIIb	Protective Eyewear Required
Optical Trapping	975	Invisible (NIR)	175 mW	IIIb	Protective Eyewear At All Times

The red laser used in the AFM lab will only cause damage if you stare at it. Viewing scattered light from the AFM laser through the stereo-microscope momentarily is safe; however, to reduce the risk of cumulative exposure, do not use the AFM for more than eight hours in one day. Protective eyewear is not required for this lab.

The green laser used in the fluorescence microscopy lab presents a special danger because its beam is unconstrained. The pointer can be aimed anywhere, and it might possibly emerge from an unexpected location on your apparatus as you build it. The beam is strong enough to cause permanent damage to your eyesight. Safety eyewear will be provided to you. You must wear it at all times when you or anyone else in the lab is building is using one of these lasers. Also, the blinking laser safety sign near the door must be turned any time work with these lasers is taking place. Needless to say, purposefully aiming the laser around the lab is an absolute no-no.

The IR laser used in the optical trap is both powerful and invisible. The power is high enough to damage your eyesight instantly. Because the beam is invisible, you may be completely unaware of its location and direction. Fortunately, the optical trap largely contains the beam. Safety goggles will be available for this lab, and must be worn any time an optical trap is in operation. Never operate an optical trap with the safety cover off. Turn on the blinking laser warning indicator any time optical traps are in use.

Chemical and biological safety

Chemicals and live cells are used in 20.309. Biosafety level 1 precautions are in effect at all times.

• Food and beverages are never allowed in the lab.
• Wear gloves when handling chemicals or biological materials.
• Wear chemical safety goggles any time there is a danger of splashing, such as when pipetting.
• Wash your hands with soap and water after handling chemiclas or biological materials and before leaving the lab.
• Report spills or injuris to an instructor immediately.
• Dispose of all materials properly.

Electrical safety

There is no risk of electrical shock from the low voltage electrical circuits you will work with in 20.309.

Never open the cover of equipment powered by 120 VAC.