How to buy the right blue/green laser pointer?

First, you need to understand what your purpose is. For demonstration applications, a green laser of 10 to 100 mW is sufficient. If it is needed for astronomy or outdoor survival, 30-500MW is recommended (the maximum for astronomy cannot exceed 200mW, otherwise it is easy to cause pilot accidents). If you must conduct laser experiments, you can choose the wattage that best suits you, and remember that there is no such thing as a 30,000mW green laser pointer. Of all the lasers available, the green laser is most obvious in the dark because its green color is most sensitive to the naked eye. Even a 5mW green laser pointer can cause temporary damage to the retina if the laser is pointed at an Angle to the glass. A powerful beam of visible light and green laser can severely damage the eyes and cause temporary blindness. Unfortunately, pre-hospital and emergency treatment is limited and largely excludes the most common eye injuries. Eye protection has no clear advantage unless there is a risk of blunt or direct penetrating eye trauma. Unnecessary shielding can make it harder for victims to see, making it almost impossible to keep their eyes open.