Will the 5mW laser pointer hurt the eyes?

First of all, we need to understand why the laser energy is so high? This is because the frequency and phase of the laser photons produced by the laser pointer are the same. The energy concentration of the laser light depends on the energy of the input material. Generally, the energy conversion efficiency of the laser material is about 10%, and the other 90% become heat energy. Lost. Even so, since the photons in the laser beam basically travel in the same direction, its energy will be concentrated on the cross section of the beam, which is why the laser energy is very powerful. Our eyes are very sensitive and delicate photosensitive organs. The fundus is densely covered with photosensitive cells, optic nerves and abundant capillaries. If you look directly at the sun for a second or two, you will feel dark in front of your eyes and it will take a long time to return to normal. Compared with sunlight, the energy of laser is more concentrated, and the damage it causes to the fundus is irreversible. So even if the Laser pointer with only 5 milliwatts irradiates the eyes for a long time, it will still cause damage to the eyes.