Defeat The Night With Image Intensifiers

Sensor fusion combines image intensifier and thermal imaging technologies into one device. Such a combination enables a user to view the image in much greater part of the light spectrum which spans from visible to near-infrared to long-wave infrared and to see the image in the visible and thermal spectrum.www.spslandforces.com

- Lt General Naresh Chand (Retd)

Image Intensifiers were primarily developed for night time viewing and surveillance under moonlight or starlight conditions. They are capable of detecting and amplifying low-light level images to appear as contrast sharp images. Over a period of time, image intensifiers have started covering a wide range of applications to include military, industrial products, inspection and scientific research, especially when combined with charge-coupled device (CCD) or Intensified CCD (ICCD) cameras.

The science and technology behind image intensifiers

In a typical image intensifier there are three components and processes which include a photocathode which converts light into photoelectrons, a microchannel plate (MCP) that multiplies electrons, and a phosphor screen that reconverts electrons into light. These are arranged in an vacuum tube.

Types. Types of image intensifiers are often broadly classified by “generation”. The first generation refers to image intensifiers that do not use an MCP and where the gain is usually no greater than 100 times. The second generation image intensifiers use MCPs for electron multiplication. MCPs using a single-stage MCP have a gain of about 10000, while those using a 3-stage MCP offer a much higher gain of more than 10 million.

Photocathode material. A variety of photocathodes materials are currently in use. Of these, photocathodes made of semiconductor crystals such as Gallium Arsenide (GaAs) and GsAs Phosphide (GsAsP) are called “third generation”. These photocathodes offer extremely high sensitivity.