Glossary

Ambient Light Amplification: The electronic intensification of moonlight, starlight, or the glow from cities or towns.

Aperture (f-number): Lens focal length divided the lens diameter – Controls the amount of light entering the objective lens.

Central Focusing: Binocular feature that allows the user to adjust both the objective and ocular lenses.

Diopter Adjustment: Ocular lens feature that allows correction for the user's eyesight.

Field of View (Angular): The angular degree of terrain visible through the night vision device.

Field of View (Linear): The width (in feet) of terrain visible through the night vision device from the specified distance - Field of view increases when magnification is decreased.

Fixed Focus: Binocular feature that allows the user to adjust the ocular lens. The objective lens focus remains fixed.

Focal Length (mm): The measure of how strongly a lens focuses light - Optical power increases as the focal length decreases.

Focus Range (ft.): Range of distance in which the night vision device is able to detect a clear image.

Generation 1: Military technology that amplifies ambient light and does not require an infrared light source.

Infrared Illuminator: Provides a light source (invisible to animal and human eyes) for the night vision device to amplify, enabling night vision in complete darkness.

Intensifier Tube: Component of night vision device that amplifies ambient light.

Line Pairs per Millimeter (lp/mm): Units used to measure resolution.

Objective Lens: The lens closest to the object being viewed - measured in mm in diameter. It collects available light, focuses it on the image intensifier, and provides image magnification.

Ocular Lens: The lens closest to the viewer's eye.

Resolution (lp/mm): The measurement of the night vision device's ability to produce a sharp image.