First Generation Image Intensifier

A first generation image intensifier works in principle as described in the image intensifier explanation, but it does not use an MCP. The electrons however are "guided" from the input to the output by means of electrostatic focussing. Two types can be distinguished: proximity focussed diodes and electrostatic inverters. In the latter a structure of electrodes form an electrostatic lens that focusses the electrons coming from cathode onto the anode. The advantage of electrostatic focussing is that it allows de-magnification of the image. This is especially interesting when these devices are coupled to small CCDs.

Advantages of first generation tubes

• Available in de-magnifying formats
• Therefore no fiber optic taper required
• No MCP noise
• High intra-scene dynamic range
• Low cost (standard models)

Disadvantages:

• Electrostatic inverters show a few percent of image distortion
• Relatively low gain
• Gating not possible
• No UV sensitivity
• Limited external gain control
• Poor over-illumination protection