Working principle of photoelectric tube

1. Photoelectric tube structure and working principle

2. Photoelectric tube Main performance
1) The volt-ampere characteristic of the photoelectric tube
The relationship between the voltage applied to the cathode of the photoelectric device and the current generated by the anode under a certain light irradiation is called the volt-ampere characteristic of the photoelectric tube.

(2) Light characteristics of phototubes
When the voltage applied between the cathode and anode of a phototube is constant, the relationship between the luminous flux and the photocurrent.
The slope of the light characteristic curve is called the sensitivity of the phototube.
1- Oxygen cesium cathode
2- Antimony cesium cathode

(3) Spectral characteristics of phototubes
Generally, phototubes with different photocathode materials have different red limit frequencies, so they can be used in different spectral ranges.
In addition, the same phototube has different sensitivities to light of different frequencies. Taking the GD-4 phototube as an example, the cathode is made of antimony-cesium material, and its red limit λc=700nm, which is highly sensitive to incident light in the visible light range. It is suitable for white light sources and is used in various photoelectric automatic detection instruments.
For infrared light sources, silver oxygen cesium cathodes are often used to form infrared detectors.
For ultraviolet light sources, antimony cesium cathodes and magnesium cadmium cathodes are often used.