Night-Vision Goggles

In the picture

1. 1Objective lens: gathers faint light from the dark scene.
2. 2Photocathode plate: converts incoming photons into electrons.
3. 3Microchannel plate: multiplies electrons through many tiny channels.
4. 4Phosphor screen: turns the electron stream into visible green light.
5. 5Eyepiece: lets the eye view the brightened green image.

Examples

• A soldier watching a dark field through night-vision goggles.
• A wildlife observer spotting nocturnal animals without a bright flashlight.

Quiz: Night-Vision Goggles (Age 17)

1. 1

   How do night-vision goggles make a dark scene visible?

   • They shine built-in lamps on the scene.
   • They electronically amplify faint light from the scene.
   • They rely only on the user’s eyes adapting to darkness.
2. 2

   Which part of night-vision goggles multiplies electrons?

   • The phosphor screen
   • The photocathode plate
   • The microchannel plate
3. 3

   Why does the image in night-vision goggles appear green?

   • Because the photocathode plate emits green light when photons hit it.
   • Because a phosphor screen glows when electrons hit it.
   • Because a green filter is placed over the eyepiece.

The answers, each with its explanation, are in the app. This lesson has left the free week, so its quiz is part of the subscription.