- K.K.Lv 51 decade agoFavorite Answer
Binoculars (night vision goggles on flight helmet)Night glasses are telescopes or binoculars with a large diameter objective. Large lenses can gather and concentrate light, thus intensifying light with purely optical means and enabling the user to see better in the dark than with naked eye alone. Often night glasses also have a fairly large exit pupil of 7 mm or more to let all gathered light into the user's eye. However, many people can't take advantage of this because of the limited dilation of the human pupil. To overcome this, soldiers were sometimes issued atropine eye drops to dilate pupils. Before the introduction of image intensifiers, night glasses were the only method of night vision, and thus were widely utilized, especially at sea. Second World War era night glasses usually had a lens diameter of 56 mm or more with magnification of seven or eight. Major drawbacks of night glasses are their large size and weight.
2008-04-12 05:50:39 補充：
Night vision approaches
Night-useful spectral range techniques make the viewer sensitive to types of light that would be invisible to a human observer. Human vision is confined to a small portion of the electromagnetic spectrum called visible light.Source(s): http://en.wikipedia.org/wiki/Night_vision