Microwave oven (microwave oven/microwave), as its name implies, is a modern cooking stove that uses microwave to heat food. Microwave is an electromagnetic wave. The microwave oven is composed of power supply, magnetron, control circuit and cooking cavity. The power supply provides about 4000 V high voltage to the magnetron. Under the excitation of the power supply, the magnetron continuously generates microwave, which is coupled to the cooking cavity through the waveguide system. Near the entrance of the cooking cavity, there is a rotatable stirrer. Because the stirrer is a fan shaped metal, it reflects microwave in all directions after rotating, so it can evenly distribute microwave energy in the cooking cavity to heat food. The power range of microwave oven is generally 500~1000 watts.

Microwave oven is a cooking appliance that uses food to absorb microwave energy in microwave field to heat itself. The microwave generated by the microwave generator in the microwave oven establishes a microwave electric field in the microwave oven cavity, and takes certain measures to make this microwave electric field as evenly distributed as possible in the oven cavity. Put food into the microwave electric field, and the control center controls its cooking time and microwave electric field strength to carry out various cooking processes.

Generally speaking, microwave is a kind of high-frequency electromagnetic wave, which does not generate heat itself. There are microwaves everywhere in the universe and nature, but there are natural microwaves. Because they are decentralized, they cannot heat food. The microwave oven uses its internal magnetron to convert electric energy into microwave, which penetrates food with a 2450MHz oscillation frequency. When the microwave is absorbed by food, the polar molecules in food (such as water, fat, protein, sugar, etc.) are attracted to oscillate rapidly at a rate of 2.45 billion times per second. The macroscopic manifestation of this oscillation is that food is heated.

The principle of microwave heating can be simply stated as follows: When microwave radiation is applied to food, food always contains a certain amount of water, and water is composed of polar molecules (the positive and negative charge centers of molecules are not coincident even when the external electric field does not exist), and the orientation of such polar molecules will change with the microwave field. Because of this movement of water polar molecules in food. As well as the interaction between adjacent molecules, a phenomenon similar to friction is generated, which makes the water temperature rise. Therefore, the temperature of food also rises. The food heated by microwave, because its interior is also heated at the same time, makes the whole object evenly heated, and the heating speed is fast. It heats the food 5 cm deep at a frequency of 2.45 billion times per second, accelerating the molecular movement.

Three taboos for using microwave oven to heat food:

1. Do not heat the meat until it is half cooked and then use the microwave oven to heat it: because bacteria will still grow in the half cooked food. The second time you use the microwave oven to heat it, because the time is short, it is impossible to kill all the bacteria, and bacteria will also grow, which will endanger human health. Frozen meat must be thawed in the microwave oven before being heated to cooked food.

2. Avoid refreezing meat that has been thawed in the microwave oven: after the meat is thawed in the microwave oven, the outside layer of the meat has actually been heated at a low temperature. At this temperature, bacteria can reproduce. Although refreezing can stop their reproduction, it cannot kill live bacteria. Therefore, if the meat that has been thawed in the microwave oven is put into the refrigerator for freezing, it must be heated until it is fully cooked.

3. Avoid fried food: because the oil content of fried food is high, and high temperature oil will splash and cause fire. In case of fire in the furnace due to carelessness, do not open the door, but turn off the power first, and then open the door to cool down after the fire is extinguished.

Use the microwave oven to heat food. Do not:

1. Do not use ordinary plastic containers: use special microwave oven containers to contain food and put it into the microwave oven for heating. First, hot food will deform the plastic container; second, ordinary plastic will release toxic substances, contaminate food and endanger human health.

2. Do not use metal utensils: because the iron, aluminum, stainless steel, enamel and other utensils put into the oven will generate electric sparks and reflect microwave when the microwave oven heats, which will not only damage the oven body but also heat uncooked food.

3. Do not use closed containers: wide mouth containers should be used when heating liquids, because the heat generated by food heating in the closed containers is not easy to dissipate, which makes the pressure in the containers too high and may cause explosion accidents. Even when frying shelled food, it is also necessary to puncture the shell with a needle or chopsticks in advance to avoid bursting, splashing and fouling the furnace wall, or splashing and injuring people after heating.

Finally, an optical fiber sensor used for temperature monitoring in the heating process of microwave oven is introduced, that is, the optical fiber temperature sensor FOT-L-SD and optical fiber temperature sensor FOT-L-BA introduced from abroad by Industrial Mining Network. FOT-L-SD and FOT-L-BA are a kind of optical fiber temperature sensors that are very suitable for measuring temperature in extreme environments, such as low temperature, nuclear environment, microwave and high intensity RF. FOT-L integrates all the excellent characteristics you expect from the ideal sensor body. Therefore, even in extreme temperatures and adverse environments, such sensors can still provide high-precision and reliable temperature measurement.

The main features of the two FOT-L temperature sensors are that they are completely free from EMI and RFI. At the same time, they are small in size, with built-in safety devices for hazardous environments, high temperature resistance, corrosion resistance and high accuracy. Based on optical fiber technology, the sensor is not affected by EMI and RFI in essence The light sensor is not electrically active, so it will not emit or be affected by any type of EM radiation, whether microwave, RF or NMR.