|Sunday, 22 October 2006|
Due to the maturation of light-emitting semiconductor laser technology in recent years, light-emitting semiconductor products have become widespread. Laser systems have many applications in the commercial, medical and educational environments. Laser light differs from ordinary light in three ways: it is monochromatic, coherent and directional. A semiconductor laser used in a typical laser pointer is mainly of a red light emitting laser diode, and in many cases, red color light close to infrared is used. Such devices typically incorporate a laser diode and a trigger circuitry used to activate the diode to generate a laser beam. This device usually has a long, thin shape similar to that of a pen, and projects a thin pointing beam from one end. These laser pointers are commonly comprised of a cylindrical casing holding a battery set, a control circuit board, a laser module and a lens. After laser rays emitted by the laser diode pass through the convex lens, the parallel light beams have a diameter of approximately 2 mm to 5 mm. The light beams appear as a single spot when directed onto a screen or object. Another type of laser pointer is such that after the laser rays penetrate the convex lens, the refraction of a columnar faceted lens produces a line-like indicating beam. The laser module which holds a laser beam is fixedly mounted inside the casing, and controlled to emit a laser beam.
Laser pointers are commonly used to provide a means for drawing attention to particular locations or items on a display. The display may be any form of visual media, as for example, a photo or drawing or picture or painting or mural or projected slide or motion picture or video display or combination thereof or other media conveying visual information to the human eye. Laser pointers typically function as indicators by projecting a distinctive spot of light onto the material being displayed. The laser pointer, as it uses a spot light for pointing the referring portion, has such advantages that it can point out any portion on the screen from a distance, and with easier in handling than a rod-like pointer, as it is provided in a compacter size. The light emitted from the pointer is non-divergent and illuminates only a limited area, which is quite preferable to explicitly point out an intended portion on the screen irrespective of a distance between the user and the screen.