What is the determinant of the brightness gain of the image intensifier?

Increasing the brightness gain of the image intensifier can take advantage of the area of the image intensifier to reduce gain and energy gain.

The main purpose of the image intensifier tube is to increase the brightness of the image for TV imaging. The ratio of the brightness of the output screen image to the brightness of the input screen image is defined as the brightness gain of the image intensifier.

The brightness gain depends on the following two factors.
1. Since the output screen area is smaller than the input screen, the electrons emitted by the photocathode will be concentratedly projected onto the smaller output phosphor screen through the electron optical system. Thus, the number of electrons received per unit area of the output screen and the number of photons excited by them will increase, thereby increasing the brightness.

This is called area reduction gain. It is equal to the ratio of the input screen area to the output screen area. For a circular screen, it is equal to the ratio of the square of the effective diameter of the input screen to the square of the effective diameter of the output screen. For example, the input screen has an effective diameter of 9 inches, the output screen has an effective diameter of 1 inch, and the reduction gain is 92=81.

Author:Alina