Laser pointer

Article summary

A laser pointer or laser pen is a (typically battery-powered) handheld device that uses a laser diode to emit a narrow low-power visible laser beam (i.e. coherent light) to highlight something of interest with a small bright colored spot. The beam may be focused with lenses. The small width of the beam and the low power of typical laser pointers make the beam itself invisible in a clean atmosphere, only showing a point of light when striking an opaque surface. Laser pointers can project a visible beam via scattering from dust particles or water droplets along the beam path. Higher-power and higher-frequency green or blue lasers may produce a beam visible even in clean air because of Rayleigh scattering from air molecules, especially when viewed in moderately-to-dimly lit conditions. The intensity of such scattering increases when these beams are viewed from angles near the beam axis. Such pointers, particularly in the green-light output range, are used as astronomical object pointers for teaching purposes. Laser pointers make a potent signaling tool, even in daylight, and are able to produce a bright signal for potential search and rescue vehicles using an inexpensive, small and lightweight device of the type that could be routinely carried in an emergency kit. There are significant safety concerns with the use of laser pointers.…

Key claims

1. date of establishment: 2011 — source: Wikipedia · confidence 0.95

Discussion questions

1. Summarise the article in your own words. Which single claim would you verify first, and why?
2. The record states that the date of establishment is "2011". What evidence would count against this claim?
3. Which claim in this article is most likely to be revised as the sources update? How would you check its current status?
4. If two sources disagreed about one of these facts, what would you need in order to trust one over the other?

Bibliography

1. Wikipedia https://en.wikipedia.org/w/index.php?oldid=1378433611