20.309:Safety

Safety

The chief hazards present in the 20.309 Lab come from: laser radiation, chemical and biological materials, and electric equipment. 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, they pose a significant risk to your vision if the beam or a reflection of it enters your eye. 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.

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 When Beam is Exposed

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.

The red laser used in the AFM lab will only cause damage if you stare at it. You will sometimes view scattered light from the AFM laser through a stereo-microscope. This is safe as long as the duration is less than eight hours. Protective eyewear is not required for this lab.

The green laser used in the fluorescence microscopy lab is perhaps most dangerous type 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 a big 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, but are not required. Never operate an optical trap with the safety cover off. Turn on the blinking laser warning indicator any time optical traps are in use.

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.
• When in doubt, check with the lab instructor.