Laser Rifle sight

A recent addition to the backyard astronomer's laser pointer 100mw

Toolkit has been flagged as a potential weapon in the terrorist's arsenal. The humble laser pointer, used by thousands of skygazers to show beginners the way to stars and constellations, is coming under fire from U.S. federal and state authorities following thousands of incidents in which laser beams have "painted" aircraft in flight.In the most notorious case, on January 4, 2005, New Jersey stargazer David Banach was charged with interfering with the operation of a passenger aircraft and lying to federal investigators. He'd been arrested the preceding week after allegedly shining a green laser at a private jet on approach to a nearby airport and then at a police helicopter dispatched to search for the culprit. The green laser pointers in common use among astronomers and the general public have a power output of a little less than 5 milliwatts; in the U.S., these are called Class 3a lasers. Lower-wattage strong laser pointer , such as those in CD players and laser printers, are Class 1 or 2, while higher-wattage units, such as those in medical or industrial equipment, are Class 3b or 4. The higher the class, the more severe the warning label required by the US Food and Drug Administration (FDA).Compared with incandescent light bulbs, which draw tens to hundreds of watts (not milliwatts), 5 mW sounds like very little. But laser light is highly concentrated into a very narrow beam. Moreover, this beam is highly collimated, meaning it diverges (spreads out) very slowly. Laser pointers typically emit a beam about a millimeter in diameter. Even as far as a kilometer away, the beam is no more than a meter across. For stargazing applications, a 5-mW green laser is completely adequate.

There is a class of lasers, IIIa, which by law must be less than 5mW (of measured optical output, not electrical input). This class is legal to sell in the United States, and legal to operate outside in the United States (local or state exceptions may exist) provided you don't do anything stupid. Shining the laser at aircraft in flight, or moving cars, or other equally moronic acts can easily land you in prison for an extended time (and rightly so). Apparently a man who wanted to see if he could hit airplanes as they were landing was in fact successful. Thankfully, none of the pilots crashed, but the man was reported to have received a seven year prison sentence.The next higher class, IIIb ranges from 5 to 500 mW. You can also legally purchase this class of laser in the United States. But there are restrictions on it's use, because these lasers are capable of permanently damaging vision. You can't use it in an Laser Pointer where the beam could escape to the outside. To be explicit here, this means you can't legally use them outside. Now you may want to adopt a "no blood, no foul" attitude, and that's fine for you. But just know that if you ever make a mistake, or run into a narrow-minded individual, you don't have a legal leg to stand on - prepare for a good screwing. Furthermore, based on my own <5mW product, there is no reason outside of inferiority complex to get a higher power product for astronomical use.The first 10,000 feet gives us a laser beam across almost 90 degrees of our view. And the next 15,000 feet of beam visually lengthens the visible beam by a size smaller than the disk of Saturn, Jupiter, or Venus. In other words, while the beam is fading out gradually, the part of it that we can actually see, the close part goes almost all the way to where we're pointing, while the long long section that fades out, adds almost no visible length to the beam. Even the section of the beam starting after one thousand feet away only lengthens the visible beam by the size of a crater on the moon that's too small to see with the naked eye.

The Orion SkyLine Deluxe Green Laser Pointer is perfect for stargazers. It emits a thin but distinct green laser beam that appears to stretch all the way to the stars! SkyLine's < 5mW green beam just keeps going and going, seemingly to infinity. It works in light-polluted or moonlit skies just as well as crystal-clear skies in remote locations. It's great for pointing out stars, planets, constellations and more for others to see. The SkyLine Deluxe now uses electronic feedback regulation to ensure ultra-stable beam intensity compared to other green lasers on the market, even in cold temperatures.
The aluminum laser pointer body is 6" long and features a convenient pocket clip. Two AAA batteries are included.Lasers have many applications like astronomy and hunting. Expecially Green Astronomy Laser Pointer can be seen in usages such as astrophysical maser and atom laser. A low-powered Laser Rifle sight is used by astronomers to easily point out stars and constellations. You can find the best astronomy laser pointer in Lasereshop.com.Have you ever been outside under a clear starry sky with a friend or family member, when you wanted to point out the location of the Orion Nebula, or trace the outline of the Sagittarius "Teapot" asterism? You point your finger, but that just doesn't cut it. "Where are you pointing? Do you mean the third bright star up from that middle pine tree over there?" Save yourself from frustration and take the guesswork out of the equation with the Orion SkyLine Deluxe Green Laser Pointer. Its bright green beam makes pointing out objects in the sky as easy as pie.

Visit any star party and you are certain to see the same scene acted out many times. Someone extends his arm and points to an object in the sky. People next to him struggle to spot the object and repeatedly fail. The problem is that because they can't sight along the arm of the person doing the directing, they see it at an angle causing an angular distortion that is all but impossible to adjust for. The director points to one star and to the observer it look like he's pointing at a completely different spot in the sky. This is a phenomenon called parallax. Fortunately, around 2004 green laser pointers became available and solved this problem.Because the human eye is more sensitive to green than red light, there is enough light reflected off dust particles in air to make the beam from a green laser pointer visible at night.as the beam from a laser pointer 300mw travels through air.Since the beam is so much longer than an arm the problem of parallax isn't a problem.By 2008 prices for green laser pointers had dropped enough so that considerably more powerful units were practical. These are attractive because their beams are longer and easier to spot. The question I wanted answered was: "How powerful a laser do you need for astronomical pointing and how do different power levels compare in the field."Repeated Internet searches failed to turn up a single site that addressed these questions so I decided to investigate them myself. This page presents the results of my studies.

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