The navigational deflector (also called the deflector dish, the deflector array or the nav deflector) is a component of many starships, and is used to deflect space debris, asteroids, microscopic particles and other objects that might collide with the ship. At FTL speed the deflector is virtually indispensable for most starships as even the most minute particle can cause serious damage to a ship when it is traveling at superluminal velocities.
The deflector commonly takes the form of a dish-shaped force beam generator containing heavy-duty subspace accelerators at the extreme forward end of the vessel's hull. It performs its primary function by emitting low-power deflector shields to deflect microscopic particles and higher-powered deflector beams and/or tractor beams to deflect larger objects.
One potential problem of using the deflector is that the deflector beams produced cause a great deal of subspace distortion, which can hinder the effectiveness of a starship's sensors, and as a result of this the long-range sensor arrays are placed in a circular fashion around the deflector. Not only does mounting the sensor arrays in this fashion reduce subspace interference by allowing both the sensors and the deflector beams to point on the same axes, essentially allowing the sensors to look through the distortion. It also allows a rapid reception of data which then could allow the computer to scan far ahead for navigational purposes.
In the event of combat, the navigation deflector performs as the very first stage of a starship's defenses - the deflector can deflect (or at least reduce the damage sustained of) most laser fire and primitive projectile weapons. However, the deflector cannot deflect more complex weaponry such as directed energy weapons or more sophisticated projectile weapons.
A deflector's energy can be extended outward to protect other ships. Ordinarily, Federation were equipped with a single external deflector dish. In recent years, some starships are known to have more than one deflector.