To make lightElectric sensorTo work well, in addition to selecting appropriate photoelectric conversion components, suitable light sources and measurement circuits must also be equipped.

1. Light emitting diode

Light emitting diode is a semiconductor device that converts electrical energy into light energy. Compared with incandescent lamps, it has the advantages of small size, low power consumption, long lifespan, fast response, high mechanical strength, and compatibility with integrated circuits. Therefore, it is widely used in computersInstruments and ApparatusesIn equipment such as automatic control.

2. Tungsten filament bulb

It is a commonly used light source with rich infrared radiation. If the spectral range of the photoelectric element is in the infrared region, a color filter can be added to filter out the visible light of the tungsten filament bulb during use, and only its infrared light source can be used to prevent interference from other light sources.

3. Arc lamp or quartz lamp

They can generate ultraviolet light, which is commonly used as a light source for measuring the concentration of suspended chemicals in liquids. The UV spotlight lens should be made of quartz or quartz glass, as ordinary glass has the ability to absorb UV rays.

4. Laser

Compared with general light sources, lasers are regular and frequency independent light waves with many advantages: highly concentrated energy, good directionality, simple frequency, and good coherence, making them ideal light sources.

Measurement circuit:

1、 Measurement circuit of photoelectric cell

The current passed through the photoelectric cell is usually very small. Therefore, its effective power is very low and cannot directly drive pen recorders or relays, so it usually needs to be connected to some kind of amplifier. When in a balanced working state, the indicating instrument is at zero position. This circuit solves the measurement errors caused by changes in the supply voltage of the photoelectric cell and the time-varying characteristics of the photoelectric cell. But there are still errors caused by inconsistent changes in dark current and sensitivity of the two phototubes over time.

2、 Measurement circuit of photomultiplier tube

If photomultiplier tubes are used for continuous monitoring of stable light sources, the positive pole of the power supply is often grounded during use, allowing the anode to be directly connected to the ground

The input terminal of the amplifier is not usedIsolation capacitorIn this way, the system will be able to respond to slowly changing light intensity. If a stable light source is modulated, capacitor coupling can be used.