Notes on Laser Safety

The base version of the spectrometer comes with a 4.5 mW Class 3R green DPSS laser. These lasers are often described as "eyes safe" although we do not like this description because it gives a sense of false security while lasers, even in Class 1, always present some risks to the eyes.

While we believe adults and young adults/students are responsible enough to assemble and operate the base version of the spectrometer, we must stress that:

• This notice is not a full laser safety training and will not subtitute to a real laser training. Owning a Class 3R laser is also illegal for natural person in some countries. Always consult official information from the laser manufacturer and local authorities first.

• You should never look directly into the beam. While it is true that the blinking reflex of your eye is fast enough to prevent severe lesions to your retina, this only applies to un-intentional exposure. Intentional exposure, such as looking directly into the laser beam, will damage your retina. More importantly, you should be aware of children and animals who might be tempted to look directly into the beam. Always keep your laser away from children and people who are not knowledgeable on laser safety.

• During normal operation when using the [standard liquid cuvette]](../cuvettes/liquid.md), the laser should be confined within the system and the power exiting from the dichroic mirror should be less than 0.5 mW. This sense of security should not distract you from observing: (a) unwanted reflections from jewelry or other metalic elements as your hand move close to the spectrometer beam path, (b) unwanted reflections as you remove/introduce a vial into the cuvette system. Apply cautions with other cuvettes system as the beam path may be exposed.

• The largest source of exposure is likely to happen during integration and alignment of the spectrometer. Beware of yourself but also of other people in the room. Never assemble the system at eyesight such as on a table where nearby people are sitting. Never operate the system in the direct viccinity of a window.

It is totaly fine to feel uneasy when using a laser, especially if you are not fully trained. In such case, you can always use laser safety goggles such as Thorlabs LG3. Check for a large optical density at 532 nm. Alternatively, there also exists alignment goggles which do not fully block the beam but allow ~1% or so of the light to pass through, easing up alignment without putting your eyesight at risks.