1. Physical and chemical fields, such as acidity meter, ion meter, viscometer, etc.

2. Thermal field, such as thermostat, hygrometer, heat-resistant thermometer, etc.

3. Mechanical field, such as electronic balance, tensiometer, hydrometer, density meter, measuring cylinder, etc.

4. Radio, such as high-frequency probe, high-power meter, spectrum analyzer, etc.

5. Length, dial indicator, steel ruler, vernier caliper, thickness gauge, etc.

6. Time and frequency, such as frequency standard instrument, frequency meter, quartz analyzer, etc.

7. Electromagnetic, such as voltmeter, impedance analyzer, millivoltmeter, etc.