What Is a Photomultiplier Tube?
Photomultiplier tubes are vacuum electronic devices that convert weak light signals into electrical signals. Photomultiplier tubes are used in optical measuring instruments and spectral analysis instruments. It can measure very weak radiant power with a wavelength of 200 ~ 1200 nanometers in low-level photometry and spectroscopy. The appearance of scintillation counters has expanded the application range of photomultiplier tubes. The development of laser detection instruments is closely related to the use of photomultiplier tubes as effective receivers. Television film transmission and image transmission are also inseparable from photomultiplier tubes. Photomultiplier tubes are widely used in the fields of metallurgy, electronics, machinery, chemical engineering, geology, medical treatment, nuclear industry, astronomy and space research.
- The photomultiplier tube converts weak light signals into electrical signals
- Photomultiplier tubes are built on
- When light hits the photocathode, the photocathode is excited into a vacuum
- The photomultiplier tube multiplication method is divided into dynode and MCP.
- Stability
- The stability of the photomultiplier tube is determined by many factors such as the characteristics of the device itself, the operating state and environmental conditions. There are many situations where the output of the pipe is unstable during the work, mainly:
- a. Jumping instability caused by poor welding of the electrodes in the tube, loose structure, poor contact of the cathode shrapnel, tip discharge between electrodes, flashover, etc., the signal is suddenly large and small.
- b. Continuity and fatigue instability caused by too large anode output current.
- c. Impact of environmental conditions on stability. As the ambient temperature increases, the sensitivity of the tube decreases.
- d. Leakage between pins caused by wet environment, causing
- Because the photomultiplier tube has high gain and short response time, and because its output current is proportional to the number of incident photons, it is widely used in
Photomultiplier tube components
- The photomultiplier tube can be divided into 4 main parts, namely: photocathode, electronic optical input system, electron multiplication system, and anode.
Photomultiplier tube advantages
- The electric multiplier is a photoelectric conversion device that further improves the sensitivity of the photocell. In addition to the photocathode and anode in the tube, multiple tile-shaped doubling electrodes are placed between the two electrodes. When in use, voltage is applied between adjacent double electrodes to accelerate electrons. The photocathode releases photoelectrons after being irradiated with light, and is directed to the first doubling electrode under the action of the electric field, causing secondary emission of the electrons, exciting more electrons, and then flying to the next doubling electrode under the action of the electric field. Many electrons. In this way, the number of electrons is continuously doubled, and the electrons collected at the anode can increase by 10 ^ 4 ~ 10 ^ 8 times. This makes the photomultiplier tube much more sensitive than ordinary phototubes and can be used to detect weak light signals. The high sensitivity and low noise of the photomultiplier tube make it widely used in light measurement.
Photomultiplier tube size
- Photomultiplier tubes have different sizes according to different applications, currently the world's largest light
- 20 inch photomultiplier tube