Subsections

• Laser safety
• Equipment care

Safety

Certain precautions should be followed to assure the safety of the students and the equipment in the Optics Laboratory.

Laser safety

The Helium-Neon laser used in the Optics Laboratory produces an intense beam of light. (The intensity of the laser beam is several orders of magnitude brighter than the sun.) To avoid injury to yourself or others, extreme care must be taken when using the laser.

The power level of the lasers used in the Optics Laboratory is approximately 0.8 mW. This is a relatively low power level for lasers. At these power levels, the laser beam will not harm the skin even upon direct exposure. However, the human eye is much more susceptible to injury by laser light. Direct exposure of the eye to the laser beam may result in injury. This is because the lens of the eye focuses the beam to a very small spot on the retina, the light sensitive layer at the back of the eye. Upon direct exposure with the beam, all the power of the laser is concentrated to a very small area on the retina, resulting in very high intensities that may lead to a local burn. Such burns in the retina may cause a degradation of vision, depending on the exact location and size. However, these hazards are easily avoided by following simple precautions.

These precautions should be followed at all times to insure the safety of yourself and others working in the Optics Laboratory:

• Never look directly into the laser beam.
• Never look directly into specular (mirror-like) reflections of the laser beam.
• Do not wear any objects on your hands and wrists that may cause specular reflection of the laser beam (such as watches or jewelry).
• Always be aware of the location of all the beams, including various low power stray reflections.
• Do not let the laser beam or any of its reflections leave the experiment table unless required by the experiment.
• Keep all the beams in a plane parallel to the experiment table.
• Do not bring your eye level down to the plane of the laser beam.
• Block the laser beam with a dark opaque object when the beam is not in use.

Laser light scattered by rough surfaces such as paper is completely harmless to the eye at low power levels. However, it is still a good idea not to stare at bright diffuse spots for a long time.

Equipment care

The equipment in the Optics Laboratory are expensive and delicate. Care should be taken to assure that the equipment is not damaged or deteriorated in any way. Precautions to avoid damage to specific components and instruments are listed with the instructions in the Equipment section. Some general precautions that have to be followed are stated here.

All optical surfaces are susceptible to be damaged easily. Some optical components have delicate optical coatings on them, and others have plastic surfaces. Fingerprints and scratches are the most common sources of damage. They may both degrade the performance of an optical component irreversibly. Certain precautions pertaining to all optical surfaces should be followed at all times to insure the safety of the optical components.

• Never touch optical surfaces. Hold all components by their side.
• Never drop optical components. Be gentle and careful. Do not rush.
• Do not lay down components on the table where they can be easily knocked away.
• Always place an optical component in its mount after you have secured the mount on the optical bench.
• Always put the components back to their case or box when you are done with them.
• Follow beam paths with a piece of paper, not with your hands or with something that may scratch optical surfaces upon accidental contact.
• If an optical surface gets dirty (fingerprints, dust, etc...) or scratched by accident, do not try to clean it. Report to the assistant immediately.
• When in doubt about the use of a particular component, always ask the laboratory assistant for help.

Care should be exercised with opto-mechanical equipment as well. Some of these equipment have delicate mechanical parts that can be easily damaged.

• Do not drop opto-mechanical components.
• Do not force any part of an opto-mechanical component.
• Do not over-tighten any screws. A controlled amount of torque is usually enough to secure a screw.