Beam Visibility

Laser pointers are battery powered hand held visible laser light sources capable of projecting a narrow beam of light over considerable distances. There are three views of interest, the first is the view of the user where one sees the beam traversing to the impact point. This view shows the actual ray and the impact point appearing as a bright dot on the target. The actual visibility of the ray will vary depending on the color, power, moisture and dust content in the air.. Range can be miles depending on the absorption of the medium. Note that the brighter the ray, the less power at the impact point. This is why on a foggy night the ray can be strikingly visible but the impact point will be of limited range.

The second view of interest is from the target point. This is where when looking towards the source the laser appears as the brightest object on the horizon and on a clear night can be visible to a distance limited only by the curvature of the earth!! If one were to compute the color temperature of a omnidirectional monochromatic source necessary to produce this effect would quickly find astronomical temperature values to millions of degrees!!

The third view is from the side where visibility will vary as the angle varies from the impact position. Minimum brightness being at right angles to the ray. Again as in the first view absorption plays a significant part where heavy moist and dusty air will enhance this viewing angle.