A Class 2 laser is safe because the blink reflex will limit the exposure to no more than 0.25 seconds. It only applies to visible-light lasers (400-700 nm). Class-2 lasers are limited to 1 mW continuous wave, or more if the emission time is less than 0.25 seconds or if the light is not spatially coherent. Intentional suppression of the blink reflex could lead to eye injury. Many green laser pointer are class 2.
However, the extent and severity of any eye injury arising from an exposure to the laser beam of a Class 3B laser will depend upon several factors including the radiant power entering the eye and the duration of the exposure. Examples of Class 3B products include lasers used for physiotherapy treatments and many research lasers.
The explanation you gave about why its much easier to see a laser pointer beam from behind it as opposed to perpendicular to it makes sense. I didnt realize the technical reason why laser beams are visible until now, and it makes sense that the beam is easier to see along its plane/parallel because its basically lighting up particles.
Take a small diameter clear tube, fill with ordinary, unfiltered tap water and line the laser up to fire down the length of the tube. Seal the far end water tight. If you're firing the beam at a downward angle, you can leave the end closest to the laser open. The impurities in the water will make the beam pretty visible. Works great even with 10 mw HeNe (red) laser.
This experiment was done with a 1mW laser. Think of how far one of those match-lighting Red Laser Pointer can reach. My pointing-at-the-moon thing might not have been that crazy after all.Adults should especially be careful about using laser pointers with green lights. A whopping 90 percent of green laser pointers in the study were not in compliance with the CFR regulations, compared to 44 percent of red laser pointers, according to the study.
The hazards of laser pointers are limited to the eye. Although with most visible lasers, the largest concern is potential damage to the retina, most laser pointers are not likely to cause retinal damage. The possible exception might be the green light lasers described above.
The Laser Engraver cannot be connected directly to the supply. You must use a current limiter or a resistor. I wonder, how many people are so stupid, that they connect it directly to maybe 12V and they are surprised, that the diode does not work. Please, read something about the VA characteristic of laser diode and about calculating resistors (Ohm's law) and current stabilisers. Do NOT spam with questions like "I connected laser to 12V and it doesn't work.
I believe that it is highly likely that the laser pointers used were high-power devices that do not comply with Japanese standard. In fact, when I used a laser pointer that was 50 times the standard, I could easily shine it on a target 300 meters in the distance. When the laser pointer was fixed to a stand and adjusted, I found that it could even reach a target 700 meters away.
[ چهارشنبه 19 آبان 1395 ] [ 9:19 ] [ michale ]